Made obtaining env variables more granular + partial Lua support.

32 files changed, 1118 insertions, 554 deletions

diff --git a/licentia/commands.md b/licentia/commands.md
index 58f3cf09b..b852e22cf 100644
--- a/licentia/commands.md
+++ b/licentia/commands.md
@@ -3,15 +3,8 @@
 ```
 ## Develop
 cd ~/lux/licentia/ \
-&& lein clean \
-&& lein lux auto build
-
-cd ~/lux/licentia/ \
 && lux clean \
-&& time lux build
-
-cd ~/lux/licentia/ \
-&& time lux test
+&& lux auto build
 ```
 
 ## Test
@@ -19,8 +12,8 @@ cd ~/lux/licentia/ \
 ```
 ## Develop
 cd ~/lux/licentia/ \
-&& lein clean \
-&& lein lux auto test
+&& lux clean \
+&& lux auto test
 ```
 
 ## Run
diff --git a/licentia/project.lux b/licentia/project.lux
index 5ef61dd16..6c025c241 100644
--- a/licentia/project.lux
+++ b/licentia/project.lux
@@ -10,6 +10,5 @@
  #dependencies [["com.github.luxlang" "stdlib" "0.6.0-SNAPSHOT" "jar"]
                 ["com.github.luxlang" "lux-jvm" "0.6.0-SNAPSHOT" "jar"]]
 
- #target "target"
  #program "program/licentia"
  #test "test/licentia"}
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/synthesis.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/synthesis.lux
index e6bd713f7..615e7a722 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/synthesis.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/synthesis.lux
@@ -51,6 +51,9 @@
       (#///analysis.Primitive analysis')
       (phase\wrap (#/.Primitive (..primitive analysis')))
 
+      (#///analysis.Reference reference)
+      (phase\wrap (#/.Reference reference))
+
       (#///analysis.Structure structure)
       (/.with_currying? false
         (case structure
@@ -64,9 +67,6 @@
               (monad.map phase.monad optimization')
               (phase\map (|>> /.tuple)))))
       
-      (#///analysis.Reference reference)
-      (phase\wrap (#/.Reference reference))
-
       (#///analysis.Case inputA branchesAB+)
       (/.with_currying? false
         (/case.synthesize optimization branchesAB+ archive inputA))
diff --git a/stdlib/source/lux/type/check.lux b/stdlib/source/lux/type/check.lux
index c308d49c0..7c5d31bf3 100644
--- a/stdlib/source/lux/type/check.lux
+++ b/stdlib/source/lux/type/check.lux
@@ -20,7 +20,7 @@
      ["n" nat ("#\." decimal)]]]]
   ["." // ("#\." equivalence)])
 
-(template: (!n/= reference subject)
+(template: (!n\= reference subject)
   ("lux i64 =" reference subject))
 
 (template: (!text\= reference subject)
@@ -53,16 +53,16 @@
 (type: #export Var
   Nat)
 
-(type: #export Assumption
+(type: Assumption
   [Type Type])
 
 (type: #export (Check a)
   (-> Type_Context (Try [Type_Context a])))
 
-(type: #export (Checker a)
+(type: (Checker a)
   (-> (List Assumption) a a (Check (List Assumption))))
 
-(type: #export Type_Vars
+(type: Type_Vars
   (List [Var (Maybe Type)]))
 
 (structure: #export functor
@@ -134,7 +134,7 @@
   (case plist
     (#.Cons [var_id var_type]
             plist')
-    (if (!n/= id var_id)
+    (if (!n\= id var_id)
       (#.Some var_type)
       (var::get id plist'))
 
@@ -149,7 +149,7 @@
 
     (#.Cons [var_id var_type]
             plist')
-    (if (!n/= id var_id)
+    (if (!n\= id var_id)
       (#.Cons [var_id value]
               plist')
       (#.Cons [var_id var_type]
@@ -291,12 +291,15 @@
       _
       (throw ..invalid_type_application [funcT argT]))))
 
-(type: #export Ring (Set Var))
+(type: Ring
+  (Set Var))
 
-(def: empty_ring Ring (set.new n.hash))
+(def: empty_ring
+  Ring
+  (set.new n.hash))
 
 ## TODO: Optimize this by not using sets anymore.
-(def: #export (ring start)
+(def: (ring start)
   (-> Var (Check Ring))
   (function (_ context)
     (loop [current start
@@ -305,7 +308,7 @@
         (#.Some (#.Some type))
         (case type
           (#.Var post)
-          (if (!n/= start post)
+          (if (!n\= start post)
             (#try.Success [context output])
             (recur post (set.add post output)))
           
@@ -390,7 +393,7 @@
 ## TODO: "check_vars" can be optimized...
 (def: (check_vars check' assumptions idE idA)
   (-> (Checker Type) (Checker Var))
-  (if (!n/= idE idA)
+  (if (!n\= idE idA)
     (check\wrap assumptions)
     (do {! ..monad}
       [ebound (attempt (peek idE))
@@ -454,6 +457,10 @@
           _
           (check' assumptions etype atype))))))
 
+(def: silent_failure!
+  (All [a] (Check a))
+  (..fail ""))
+
 ## TODO: "check_apply" can be optimized...
 (def: (check_apply check' assumptions expected actual)
   (-> (Checker Type) (Checker [Type Type]))
@@ -461,9 +468,9 @@
         [actual_input actual_function] actual]
     (case [expected_function actual_function]
       [(#.Ex exE) (#.Ex exA)]
-      (if (!n/= exE exA)
+      (if (!n\= exE exA)
         (check' assumptions expected_input actual_input)
-        (fail ""))
+        ..silent_failure!)
 
       [(#.UnivQ _ _) (#.Ex _)]
       (do ..monad
@@ -493,7 +500,7 @@
       [(#.Var id) _]
       (function (_ context)
         (case ((do ..monad
-                 [expected_function' (read! id)]
+                 [expected_function' (..read! id)]
                  (check' assumptions (#.Apply expected_input expected_function') (#.Apply actual)))
                context)
           (#try.Success output)
@@ -539,20 +546,20 @@
            context)))
 
       _
-      (fail ""))))
+      ..silent_failure!)))
 
 (def: (with exception parameter check)
   (All [e a] (-> (Exception e) e (Check a) (Check a)))
   (|>> check (exception.with exception parameter)))
 
 ## TODO: "check'" can be optimized...
-(def: #export (check' assumptions expected actual)
+(def: (check' assumptions expected actual)
   {#.doc "Type-check to ensure that the 'expected' type subsumes the 'actual' type."}
   (Checker Type)
   (if (for {@.php false} ## TODO: Remove this once JPHP is gone.
            (is? expected actual))
     (check\wrap assumptions)
-    (with type_check_failed [expected actual]
+    (with ..type_check_failed [expected actual]
       (case [expected actual]
         [(#.Var idE) (#.Var idA)]
         (check_vars check' assumptions idE idA)
@@ -625,8 +632,8 @@
                 (recur assumptions' e_tail a_tail))
 
               _
-              (fail "")))
-          (fail ""))
+              ..silent_failure!))
+          ..silent_failure!)
 
         (^template [<compose>]
           [[(<compose> eL eR) (<compose> aL aR)]
@@ -642,9 +649,9 @@
           (check' assumptions eO aO))
 
         [(#.Ex e!id) (#.Ex a!id)]
-        (if (!n/= e!id a!id)
+        (if (!n\= e!id a!id)
           (check\wrap assumptions)
-          (fail ""))
+          ..silent_failure!)
 
         [(#.Named _ ?etype) _]
         (check' assumptions ?etype actual)
@@ -653,7 +660,7 @@
         (check' assumptions expected ?atype)
 
         _
-        (fail "")))))
+        ..silent_failure!))))
 
 (def: #export (check expected actual)
   {#.doc "Type-check to ensure that the 'expected' type subsumes the 'actual' type."}
@@ -663,7 +670,7 @@
 (def: #export (checks? expected actual)
   {#.doc "A simple type-checking function that just returns a yes/no answer."}
   (-> Type Type Bit)
-  (case (run fresh_context (check' (list) expected actual))
+  (case (..run ..fresh_context (..check' (list) expected actual))
     (#try.Failure _)
     false
 
diff --git a/stdlib/source/lux/world/program.lux b/stdlib/source/lux/world/program.lux
index f04ef63dd..ae0c6d840 100644
--- a/stdlib/source/lux/world/program.lux
+++ b/stdlib/source/lux/world/program.lux
@@ -3,11 +3,12 @@
    ["@" target]
    ["." ffi (#+ import:)]
    [abstract
-    ["." monad (#+ do)]]
+    ["." monad (#+ Monad do)]]
    [control
     ["." function]
     ["." io (#+ IO)]
-    ["." try]
+    ["." try (#+ Try)]
+    ["." exception (#+ exception:)]
     [concurrency
      ["." atom]
      ["." promise (#+ Promise)]]
@@ -19,9 +20,11 @@
     ["." text
      ["%" format (#+ format)]]
     [collection
-     ["." array (#+ Array) ("#\." fold)]
+     ["." array (#+ Array)]
      ["." dictionary (#+ Dictionary)]
      ["." list ("#\." functor)]]]
+   [macro
+    ["." template]]
    [math
     [number
      ["i" int]]]
@@ -31,9 +34,15 @@
    [file (#+ Path)]
    [shell (#+ Exit)]])
 
+(exception: #export (unknown_environment_variable {name Text})
+  (exception.report
+   ["Name" (%.text name)]))
+
 (signature: #export (Program !)
-  (: (-> Any (! Environment))
-     environment)
+  (: (-> Any (! (List Text)))
+     available_variables)
+  (: (-> Text (! (Try Text)))
+     variable)
   (: (-> Any (! Path))
      home)
   (: (-> Any (! Path))
@@ -41,24 +50,50 @@
   (: (-> Exit (! Nothing))
      exit))
 
-(def: #export (async program)
-  (-> (Program IO) (Program Promise))
-  (structure
-   (def: environment
-     (|>> (\ program environment) promise.future))
-   (def: home
-     (|>> (\ program home) promise.future))
-   (def: directory
-     (|>> (\ program directory) promise.future))
-   (def: exit
-     (|>> (\ program exit) promise.future))))
+(def: #export (environment monad program)
+  (All [!] (-> (Monad !) (Program !) (! Environment)))
+  (do {! monad}
+    [variables (\ program available_variables [])
+     entries (monad.map ! (function (_ name)
+                            (\ ! map (|>> [name]) (\ program variable name)))
+                        variables)]
+    (wrap (|> entries
+              (list.all (function (_ [name value])
+                          (case value
+                            (#try.Success value)
+                            (#.Some [name value])
+                            
+                            (#try.Failure _)
+                            #.None)))
+              (dictionary.from_list text.hash)))))
+
+(`` (structure: #export (async program)
+      (-> (Program IO) (Program Promise))
+
+      (~~ (template [<method>]
+            [(def: <method>
+               (|>> (\ program <method>) promise.future))]
+
+            [available_variables]
+            [variable]
+            [home]
+            [directory]
+            [exit]
+            ))))
 
 (def: #export (mock environment home directory)
   (-> Environment Path Path (Program IO))
   (let [@dead? (atom.atom false)]
     (structure
-     (def: environment
-       (function.constant (io.io environment)))
+     (def: available_variables
+       (function.constant (io.io (dictionary.keys environment))))
+     (def: (variable name)
+       (io.io (case (dictionary.get name environment)
+                (#.Some value)
+                (#try.Success value)
+
+                #.None
+                (exception.throw ..unknown_environment_variable [name]))))
      (def: home
        (function.constant (io.io home)))
      (def: directory
@@ -71,11 +106,6 @@
 
 (with_expansions [<jvm> (as_is (import: java/lang/String)
 
-                               (import: (java/util/Map$Entry k v)
-                                 ["#::."
-                                  (getKey [] k)
-                                  (getValue [] v)])
-
                                (import: (java/util/Iterator a)
                                  ["#::."
                                   (hasNext [] boolean)
@@ -87,35 +117,21 @@
 
                                (import: (java/util/Map k v)
                                  ["#::."
-                                  (entrySet [] (java/util/Set (java/util/Map$Entry k v)))])
+                                  (keySet [] (java/util/Set k))])
 
                                (import: java/lang/System
                                  ["#::."
                                   (#static getenv [] (java/util/Map java/lang/String java/lang/String))
+                                  (#static getenv #as resolveEnv [java/lang/String] #io #? java/lang/String)
                                   (#static getProperty [java/lang/String] #? java/lang/String)
                                   (#static exit [int] #io void)])
 
-                               (def: (jvm\\consume f iterator)
-                                 (All [a b] (-> (-> a b) (java/util/Iterator a) (List b)))
+                               (def: (jvm\\consume iterator)
+                                 (All [a] (-> (java/util/Iterator a) (List a)))
                                  (if (java/util/Iterator::hasNext iterator)
-                                   (#.Cons (f (java/util/Iterator::next iterator))
-                                           (jvm\\consume f iterator))
+                                   (#.Cons (java/util/Iterator::next iterator)
+                                           (jvm\\consume iterator))
                                    #.Nil))
-
-                               (def: (jvm\\to_kv entry)
-                                 (All [k v] (-> (java/util/Map$Entry k v) [k v]))
-                                 [(java/util/Map$Entry::getKey entry)
-                                  (java/util/Map$Entry::getValue entry)])
-
-                               (def: jvm\\environment
-                                 (IO Environment)
-                                 (with_expansions [<jvm> (as_is (io.io (|> (java/lang/System::getenv)
-                                                                           java/util/Map::entrySet
-                                                                           java/util/Set::iterator
-                                                                           (..jvm\\consume ..jvm\\to_kv)
-                                                                           (dictionary.from_list text.hash))))]
-                                   (for {@.old <jvm>
-                                         @.jvm <jvm>})))
                                )]
   (for {@.old (as_is <jvm>)
         @.jvm (as_is <jvm>)
@@ -189,7 +205,7 @@
                         (import: os/environ
                           ["#::."
                            (#static keys [] #io (Array ffi.String))
-                           (#static get [ffi.String] #io ffi.String)]))
+                           (#static get [ffi.String] #io #? ffi.String)]))
         @.lua (as_is (ffi.import: LuaFile
                        ["#::."
                         (read [ffi.String] #io #? ffi.String)
@@ -220,7 +236,7 @@
         @.ruby (as_is (ffi.import: Env #as RubyEnv
                         ["#::."
                          (#static keys [] (Array Text))
-                         (#static fetch [Text] Text)])
+                         (#static fetch [Text] #io #? Text)])
 
                       (ffi.import: "fileutils" FileUtils #as RubyFileUtils
                         ["#::."
@@ -234,85 +250,106 @@
                         ["#::."
                          (#static exit [Int] #io Nothing)]))
 
-        @.php
-        (as_is (ffi.import: (exit [Int] #io Nothing))
-               ## https://www.php.net/manual/en/function.exit.php
-               (ffi.import: (getcwd [] #io ffi.String))
-               ## https://www.php.net/manual/en/function.getcwd.php
-               (ffi.import: (getenv #as getenv/1 [ffi.String] #io ffi.String))
-               (ffi.import: (getenv #as getenv/0 [] #io (Array ffi.String)))
-               ## https://www.php.net/manual/en/function.getenv.php
-               ## https://www.php.net/manual/en/function.array-keys.php
-               (ffi.import: (array_keys [(Array ffi.String)] (Array ffi.String)))
-               )
-
-        @.scheme
-        (as_is (ffi.import: (exit [Int] #io Nothing))
-               ## https://srfi.schemers.org/srfi-98/srfi-98.html
-               (abstract: Pair Any)
-               (abstract: PList Any)
-               (ffi.import: (get-environment-variables [] #io PList))
-               (ffi.import: (car [Pair] Text))
-               (ffi.import: (cdr [Pair] Text))
-               (ffi.import: (car #as head [PList] Pair))
-               (ffi.import: (cdr #as tail [PList] PList)))}
+        ## @.php
+        ## (as_is (ffi.import: (exit [Int] #io Nothing))
+        ##        ## https://www.php.net/manual/en/function.exit.php
+        ##        (ffi.import: (getcwd [] #io ffi.String))
+        ##        ## https://www.php.net/manual/en/function.getcwd.php
+        ##        (ffi.import: (getenv #as getenv/1 [ffi.String] #io ffi.String))
+        ##        (ffi.import: (getenv #as getenv/0 [] #io (Array ffi.String)))
+        ##        ## https://www.php.net/manual/en/function.getenv.php
+        ##        ## https://www.php.net/manual/en/function.array-keys.php
+        ##        (ffi.import: (array_keys [(Array ffi.String)] (Array ffi.String)))
+        ##        )
+
+        ## @.scheme
+        ## (as_is (ffi.import: (exit [Int] #io Nothing))
+        ##        ## https://srfi.schemers.org/srfi-98/srfi-98.html
+        ##        (abstract: Pair Any)
+        ##        (abstract: PList Any)
+        ##        (ffi.import: (get-environment-variables [] #io PList))
+        ##        (ffi.import: (car [Pair] Text))
+        ##        (ffi.import: (cdr [Pair] Text))
+        ##        (ffi.import: (car #as head [PList] Pair))
+        ##        (ffi.import: (cdr #as tail [PList] PList)))
+        }
        (as_is)))
 
 (structure: #export default
   (Program IO)
 
-  (def: (environment _)
-    (with_expansions [<jvm> ..jvm\\environment]
+  (def: (available_variables _)
+    (with_expansions [<jvm> (io.io (|> (java/lang/System::getenv)
+                                       java/util/Map::keySet
+                                       java/util/Set::iterator
+                                       ..jvm\\consume))]
       (for {@.old <jvm>
             @.jvm <jvm>
             @.js (io.io (if ffi.on_node_js?
                           (case (ffi.constant Object [process env])
                             (#.Some process/env)
-                            (array\fold (function (_ entry environment)
-                                          (<| (maybe.default environment)
-                                              (do maybe.monad
-                                                [variable (array.read 0 entry)
-                                                 value (array.read 1 entry)]
-                                                (wrap (dictionary.put variable value environment)))))
-                                        environment.empty
-                                        (Object::entries [process/env]))
+                            (|> (Object::entries [process/env])
+                                array.to_list
+                                (list\map (|>> (array.read 0) maybe.assume)))
 
                             #.None
-                            (undefined))
-                          environment.empty))
-            @.python (do {! io.monad}
-                       [keys (os/environ::keys [])]
-                       (monad.fold ! (function (_ variable environment)
-                                       (do !
-                                         [value (os/environ::get [variable])]
-                                         (wrap (dictionary.put variable value environment))))
-                                   environment.empty
-                                   (array.to_list keys)))
+                            (list))
+                          (list)))
+            @.python (\ io.monad map array.to_list (os/environ::keys []))
+            ## Lua offers no way to get all the environment variables available.
+            @.lua (io.io (list))
             @.ruby (|> (RubyEnv::keys [])
                        array.to_list
                        (list\map (function (_ variable)
                                    [variable (RubyEnv::fetch [variable])]))
                        (dictionary.from_list text.hash)
                        io.io)
-            @.php (do io.monad
-                    [environment (..getenv/0 [])]
-                    (wrap (|> environment
-                              ..array_keys
-                              array.to_list
-                              (list\map (function (_ variable)
-                                          [variable ("php array read" (:coerce Nat variable) environment)]))
-                              (dictionary.from_list text.hash))))
-            @.scheme (do io.monad
-                       [input (..get-environment-variables [])]
-                       (loop [input input
-                              output environment.empty]
-                         (if ("scheme object nil?" input)
-                           (wrap output)
-                           (let [entry (..head input)]
-                             (recur (..tail input)
-                                    (dictionary.put (..car entry) (..cdr entry) output))))))}
-           ## TODO: Replace dummy implementation.
-           (io.io environment.empty))))
+            ## @.php (do io.monad
+            ##         [environment (..getenv/0 [])]
+            ##         (wrap (|> environment
+            ##                   ..array_keys
+            ##                   array.to_list
+            ##                   (list\map (function (_ variable)
+            ##                               [variable ("php array read" (:coerce Nat variable) environment)]))
+            ##                   (dictionary.from_list text.hash))))
+            ## @.scheme (do io.monad
+            ##            [input (..get-environment-variables [])]
+            ##            (loop [input input
+            ##                   output environment.empty]
+            ##              (if ("scheme object nil?" input)
+            ##                (wrap output)
+            ##                (let [entry (..head input)]
+            ##                  (recur (..tail input)
+            ##                         (dictionary.put (..car entry) (..cdr entry) output))))))
+            })))
+
+  (def: (variable name)
+    (template.let [(!fetch <method>)
+                   [(do io.monad
+                      [value (<method> name)]
+                      (wrap (case value
+                              (#.Some value)
+                              (#try.Success value)
+
+                              #.None
+                              (exception.throw ..unknown_environment_variable [name]))))]]
+      (with_expansions [<jvm> (!fetch java/lang/System::resolveEnv)]
+        (for {@.old <jvm>
+              @.jvm <jvm>
+              @.js (io.io (if ffi.on_node_js?
+                            (case (do maybe.monad
+                                    [process/env (ffi.constant Object [process env])]
+                                    (array.read (: Nat name) process/env))
+                              (#.Some value)
+                              (#try.Success value)
+
+                              #.None
+                              (exception.throw ..unknown_environment_variable [name]))
+                            (exception.throw ..unknown_environment_variable [name])))
+              @.python (!fetch os/environ::get)
+              @.lua (!fetch os/getenv)
+              @.ruby (!fetch RubyEnv::fetch)
+              }))))
   
   (def: (home _)
     (with_expansions [<default> (io.io "~")
@@ -327,11 +364,12 @@
             @.python (os/path::expanduser ["~"])
             @.lua (..run_command "~" "echo ~")
             @.ruby (RubyDir::home [])
-            @.php (do io.monad
-                    [output (..getenv/1 ["HOME"])]
-                    (wrap (if (bit\= false (:coerce Bit output))
-                            "~"
-                            output)))}
+            ## @.php (do io.monad
+            ##         [output (..getenv/1 ["HOME"])]
+            ##         (wrap (if (bit\= false (:coerce Bit output))
+            ##                 "~"
+            ##                 output)))
+            }
            ## TODO: Replace dummy implementation.
            <default>)))
 
@@ -356,11 +394,12 @@
                       (..run_command default "pwd")
                       (wrap on_windows)))
             @.ruby (RubyFileUtils::pwd [])
-            @.php (do io.monad
-                    [output (..getcwd [])]
-                    (wrap (if (bit\= false (:coerce Bit output))
-                            "."
-                            output)))}
+            ## @.php (do io.monad
+            ##         [output (..getcwd [])]
+            ##         (wrap (if (bit\= false (:coerce Bit output))
+            ##                 "."
+            ##                 output)))
+            }
            ## TODO: Replace dummy implementation.
            (io.io <default>))))
   
@@ -381,5 +420,6 @@
             @.python (os::_exit [code])
             @.lua (os/exit [code])
             @.ruby (RubyKernel::exit [code])
-            @.php (..exit [code])
-            @.scheme (..exit [code])}))))
+            ## @.php (..exit [code])
+            ## @.scheme (..exit [code])
+            }))))
diff --git a/stdlib/source/program/aedifex/command/auto.lux b/stdlib/source/program/aedifex/command/auto.lux
index 000384ccd..f74d3069a 100644
--- a/stdlib/source/program/aedifex/command/auto.lux
+++ b/stdlib/source/program/aedifex/command/auto.lux
@@ -65,7 +65,7 @@
                        (monad.map ! (..targets fs))
                        (\ ! map list.concat))]
           (do {! ///action.monad}
-            [_ (monad.map ! (\ watcher start watch.all) targets)
+            [_ (monad.map ! (\ watcher start watch.modification) targets)
              _ <call>]
             (loop [_ []]
               (do !
diff --git a/stdlib/source/program/aedifex/command/build.lux b/stdlib/source/program/aedifex/command/build.lux
index e2d6f78b8..6d61475d0 100644
--- a/stdlib/source/program/aedifex/command/build.lux
+++ b/stdlib/source/program/aedifex/command/build.lux
@@ -23,7 +23,7 @@
     [number
      ["i" int]]]
    [world
-    [program (#+ Program)]
+    ["." program (#+ Program)]
     ["." file (#+ Path)]
     ["." shell (#+ Process Shell)]
     ["." console (#+ Console)]
@@ -76,7 +76,6 @@
 
 (exception: #export no_available_compiler)
 (exception: #export no_specified_program)
-(exception: #export no_specified_target)
 
 (type: #export Compiler
   (#JVM Dependency)
@@ -169,45 +168,42 @@
 (def: #export (do! console program fs shell resolution)
   (-> (Console Promise) (Program Promise) (file.System Promise) (Shell Promise) Resolution (Command [Compiler Path]))
   (function (_ profile)
-    (case [(get@ #///.program profile)
-           (get@ #///.target profile)]
-      [#.None _]
-      (promise\wrap (exception.throw ..no_specified_program []))
-
-      [_ #.None]
-      (promise\wrap (exception.throw ..no_specified_target []))
-      
-      [(#.Some program_module) (#.Some target)]
-      (do promise.monad
-        [environment (\ program environment [])
-         home (\ program home [])
-         working_directory (\ program directory [])]
-        (do ///action.monad
-          [[resolution compiler] (promise\wrap (..compiler resolution))
-           #let [[[command compiler_params] output] (case compiler
-                                                      (#JVM dependency) [(///runtime.java (..path fs home dependency))
-                                                                         "program.jar"]
-                                                      (#JS dependency) [(///runtime.node (..path fs home dependency))
-                                                                        "program.js"])
-                 / (\ fs separator)
-                 cache_directory (format working_directory / target)]
-           _ (console.write_line ..start console)
-           process (!.use (\ shell execute)
-                          [environment
-                           working_directory
-                           command
-                           (list.concat (list compiler_params
-                                              (list "build")
-                                              (..plural "--library" (..libraries fs home resolution))
-                                              (..plural "--source" (set.to_list (get@ #///.sources profile)))
-                                              (..singular "--target" cache_directory)
-                                              (..singular "--module" program_module)))])
-           _ (..log_output! console process)
-           _ (..log_error! console process)
-           exit (!.use (\ process await) [])
-           _ (console.write_line (if (i.= shell.normal exit)
-                                   ..success
-                                   ..failure)
-                                 console)]
-          (wrap [compiler
-                 (format cache_directory / output)]))))))
+    (let [target (get@ #///.target profile)]
+      (case (get@ #///.program profile)
+        #.None
+        (promise\wrap (exception.throw ..no_specified_program []))
+
+        (#.Some program_module)
+        (do promise.monad
+          [environment (program.environment promise.monad program)
+           home (\ program home [])
+           working_directory (\ program directory [])]
+          (do ///action.monad
+            [[resolution compiler] (promise\wrap (..compiler resolution))
+             #let [[[command compiler_params] output] (case compiler
+                                                        (#JVM dependency) [(///runtime.java (..path fs home dependency))
+                                                                           "program.jar"]
+                                                        (#JS dependency) [(///runtime.node (..path fs home dependency))
+                                                                          "program.js"])
+                   / (\ fs separator)
+                   cache_directory (format working_directory / target)]
+             _ (console.write_line ..start console)
+             process (!.use (\ shell execute)
+                            [environment
+                             working_directory
+                             command
+                             (list.concat (list compiler_params
+                                                (list "build")
+                                                (..plural "--library" (..libraries fs home resolution))
+                                                (..plural "--source" (set.to_list (get@ #///.sources profile)))
+                                                (..singular "--target" cache_directory)
+                                                (..singular "--module" program_module)))])
+             _ (..log_output! console process)
+             _ (..log_error! console process)
+             exit (!.use (\ process await) [])
+             _ (console.write_line (if (i.= shell.normal exit)
+                                     ..success
+                                     ..failure)
+                                   console)]
+            (wrap [compiler
+                   (format cache_directory / output)])))))))
diff --git a/stdlib/source/program/aedifex/command/clean.lux b/stdlib/source/program/aedifex/command/clean.lux
index 900de2cc4..ecb71b59d 100644
--- a/stdlib/source/program/aedifex/command/clean.lux
+++ b/stdlib/source/program/aedifex/command/clean.lux
@@ -8,6 +8,9 @@
      ["!" capability]]
     [concurrency
      ["." promise (#+ Promise)]]]
+   [data
+    [text
+     ["%" format (#+ format)]]]
    [world
     ["." file (#+ Path File Directory)]
     ["." console (#+ Console)]]]
@@ -26,27 +29,21 @@
                   nodes)]
     (wrap [])))
 
-(def: #export success
-  "Success")
-
-(def: #export failure
-  "Failure: No 'target' defined for clean-up.")
+(def: #export (success path)
+  (-> ///.Target Text)
+  (format "Successfully cleaned target directory: " path))
 
 (def: #export (do! console fs profile)
   (-> (Console Promise) (file.System Promise) (Command Any))
-  (case (get@ #///.target profile)
-    (#.Some target)
-    (do {! ///action.monad}
-      [target (: (Promise (Try (Directory Promise)))
-                 (!.use (\ fs directory) target))
-       _ (loop [root target]
-           (do !
-             [_ (..clean_files! root)
-              subs (: (Promise (Try (List (Directory Promise))))
-                      (!.use (\ root directories) []))
-              _ (monad.map ! recur subs)]
-             (!.use (\ root discard) [])))]
-      (console.write_line ..success console))
-    
-    #.None
-    (console.write_line ..failure console)))
+  (do {! ///action.monad}
+    [#let [target (get@ #///.target profile)]
+     root (: (Promise (Try (Directory Promise)))
+             (!.use (\ fs directory) target))
+     _ (loop [root root]
+         (do !
+           [_ (..clean_files! root)
+            subs (: (Promise (Try (List (Directory Promise))))
+                    (!.use (\ root directories) []))
+            _ (monad.map ! recur subs)]
+           (!.use (\ root discard) [])))]
+    (console.write_line (..success target) console)))
diff --git a/stdlib/source/program/aedifex/command/deploy.lux b/stdlib/source/program/aedifex/command/deploy.lux
index 6546045a4..5ec42be78 100644
--- a/stdlib/source/program/aedifex/command/deploy.lux
+++ b/stdlib/source/program/aedifex/command/deploy.lux
@@ -52,6 +52,9 @@
      ["#/." extension (#+ Extension)]
      ["#/." type]]]])
 
+(def: #export success
+  "Successfully deployed the project.")
+
 (def: #export (do! console repository fs artifact profile)
   (-> (Console Promise) (Repository Promise) (file.System Promise) Artifact (Command Any))
   (do {! ///action.monad}
@@ -73,4 +76,4 @@
            #///package.pom [pom
                             pom_data
                             (///dependency/status.verified pom_data)]}))]
-    (console.write_line //clean.success console)))
+    (console.write_line ..success console)))
diff --git a/stdlib/source/program/aedifex/command/deps.lux b/stdlib/source/program/aedifex/command/deps.lux
index d699de528..36a129bd1 100644
--- a/stdlib/source/program/aedifex/command/deps.lux
+++ b/stdlib/source/program/aedifex/command/deps.lux
@@ -45,7 +45,6 @@
       [cached (|> (dictionary.keys cache)
                   (list\fold dictionary.remove resolution)
                   (///dependency/deployment.all local))
-       _ (console.write_line //clean.success console)
        _ (console.write_line (exception.report
                               ["Local successes" (exception.enumerate ..format local_successes)]
                               ["Local failures" (exception.enumerate ..format local_failures)]
diff --git a/stdlib/source/program/aedifex/command/install.lux b/stdlib/source/program/aedifex/command/install.lux
index 375e803ce..2e5ce6d89 100644
--- a/stdlib/source/program/aedifex/command/install.lux
+++ b/stdlib/source/program/aedifex/command/install.lux
@@ -45,6 +45,9 @@
     ["#." artifact (#+ Artifact)
      ["#/." type]]]])
 
+(def: #export success
+  "Successfully installed the project locally.")
+
 (def: #export failure
   "Failure: No 'identity' defined for the project.")
 
@@ -66,7 +69,7 @@
                                           #///package.pom [pom
                                                            pom_data
                                                            (///dependency/status.verified pom_data)]}))]
-      (console.write_line //clean.success console))
+      (console.write_line ..success console))
 
     _
     (console.write_line ..failure console)))
diff --git a/stdlib/source/program/aedifex/command/pom.lux b/stdlib/source/program/aedifex/command/pom.lux
index 7ca26c311..16d036718 100644
--- a/stdlib/source/program/aedifex/command/pom.lux
+++ b/stdlib/source/program/aedifex/command/pom.lux
@@ -25,6 +25,9 @@
     ["#." action (#+ Action)]
     ["#." pom]]])
 
+(def: #export success
+  (format "Successfully created POM file: " ///pom.file))
+
 (def: #export (do! console fs profile)
   (-> (Console Promise) (file.System Promise) (Command Path))
   (do ///action.monad
@@ -35,5 +38,5 @@
                  (\ xml.codec encode)
                  (\ utf8.codec encode)
                  (!.use (\ file over_write)))
-     _ (console.write_line //clean.success console)]
+     _ (console.write_line ..success console)]
     (wrap ///pom.file)))
diff --git a/stdlib/source/program/aedifex/command/test.lux b/stdlib/source/program/aedifex/command/test.lux
index e717b7cd6..f3ab6c12a 100644
--- a/stdlib/source/program/aedifex/command/test.lux
+++ b/stdlib/source/program/aedifex/command/test.lux
@@ -14,7 +14,7 @@
     [number
      ["i" int]]]
    [world
-    [program (#+ Program)]
+    ["." program (#+ Program)]
     ["." file]
     ["." shell (#+ Shell)]
     ["." console (#+ Console)]]]
@@ -35,7 +35,7 @@
 (def: #export (do! console program fs shell resolution profile)
   (-> (Console Promise) (Program Promise) (file.System Promise) (Shell Promise) Resolution (Command Any))
   (do promise.monad
-    [environment (\ program environment [])
+    [environment (program.environment promise.monad program)
      working_directory (\ program directory [])]
     (do ///action.monad
       [[compiler program] (//build.do! console program fs shell resolution
diff --git a/stdlib/source/program/aedifex/dependency/deployment.lux b/stdlib/source/program/aedifex/dependency/deployment.lux
index 963602494..0fdf7956f 100644
--- a/stdlib/source/program/aedifex/dependency/deployment.lux
+++ b/stdlib/source/program/aedifex/dependency/deployment.lux
@@ -23,7 +23,7 @@
     [format
      ["." xml]]]
    [time
-    ["." instant]]
+    ["." instant (#+ Instant)]]
    [world
     [program (#+ Program)]
     ["." file (#+ Path File Directory)]]]
@@ -32,6 +32,7 @@
    ["#." hash (#+ Hash SHA-1 MD5)]
    ["#." package (#+ Package)]
    ["#." artifact (#+ Artifact)
+    ["#/." time]
     ["#/." type]
     ["#/." extension (#+ Extension)]
     ["#/." versioning]
@@ -40,7 +41,7 @@
       ["#/." value]]]]
    ["#." metadata
     ["#/." artifact]
-    ["#/." snapshot]]
+    ["#/." snapshot (#+ Metadata)]]
    ["#." dependency (#+ Dependency)
     [resolution (#+ Resolution)]
     ["#/." status (#+ Status)]]
@@ -93,6 +94,35 @@
              (#///dependency/status.Verified _)
              (list <sha-1> <md5>)))))
 
+(def: (update_snapshot [artifact type] now snapshot)
+  (-> Dependency Instant Metadata (Try Metadata))
+  (do try.monad
+    [now (: (Try ///artifact/time.Time)
+            (///artifact/time.from_instant now))
+     #let [version_template (get@ #///artifact.version artifact)
+           snapshot (|> snapshot
+                        (update@ [#///metadata/snapshot.versioning #///artifact/versioning.snapshot]
+                                 (function (_ snapshot)
+                                   (case snapshot
+                                     #///artifact/snapshot.Local
+                                     #///artifact/snapshot.Local
+                                     
+                                     (#///artifact/snapshot.Remote [_ build])
+                                     (#///artifact/snapshot.Remote [now (inc build)]))))
+                        (set@ [#///metadata/snapshot.versioning #///artifact/versioning.last_updated] now))
+           versioning_snapshot (get@ [#///metadata/snapshot.versioning #///artifact/versioning.snapshot] snapshot)]]
+    (wrap (|> snapshot
+              (set@ [#///metadata/snapshot.versioning #///artifact/versioning.versions]
+                    (list {#///artifact/snapshot/version.extension type
+                           #///artifact/snapshot/version.value (///artifact/snapshot/version/value.format
+                                                                {#///artifact/snapshot/version/value.version version_template
+                                                                 #///artifact/snapshot/version/value.snapshot versioning_snapshot})
+                           #///artifact/snapshot/version.updated now}))
+              ## (set@ [#///metadata/snapshot.versioning #///artifact/versioning.snapshot]
+              ##       (list\compose (..artifacts type (product.right (get@ #///package.library package)))
+              ##                     (..artifacts ///artifact/type.pom (product.right (get@ #///package.pom package)))))
+              ))))
+
 (def: #export (one repository [artifact type] package)
   (-> (Repository Promise) Dependency Package (Promise (Try Artifact)))
   (do {! promise.monad}
@@ -109,28 +139,8 @@
               status]))
 
        snapshot (///metadata/snapshot.read repository artifact)
-       #let [snapshot (|> snapshot
-                          (update@ [#///metadata/snapshot.versioning #///artifact/versioning.snapshot]
-                                   (function (_ snapshot)
-                                     (case snapshot
-                                       #///artifact/snapshot.Local
-                                       #///artifact/snapshot.Local
-                                       
-                                       (#///artifact/snapshot.Remote [_ build])
-                                       (#///artifact/snapshot.Remote [now (inc build)]))))
-                          (set@ [#///metadata/snapshot.versioning #///artifact/versioning.last_updated] now))
-             versioning_snapshot (get@ [#///metadata/snapshot.versioning #///artifact/versioning.snapshot] snapshot)]
-       _ (|> snapshot
-             (set@ [#///metadata/snapshot.versioning #///artifact/versioning.versions]
-                   (list {#///artifact/snapshot/version.extension type
-                          #///artifact/snapshot/version.value (///artifact/snapshot/version/value.format
-                                                               {#///artifact/snapshot/version/value.version version_template
-                                                                #///artifact/snapshot/version/value.snapshot versioning_snapshot})
-                          #///artifact/snapshot/version.updated now}))
-             ## (set@ [#///metadata/snapshot.versioning #///artifact/versioning.snapshot]
-             ##       (list\compose (..artifacts type (product.right (get@ #///package.library package)))
-             ##                     (..artifacts ///artifact/type.pom (product.right (get@ #///package.pom package)))))
-             (///metadata/snapshot.write repository artifact))
+       snapshot (\ ! wrap (..update_snapshot [artifact type] now snapshot))
+       _ (///metadata/snapshot.write repository artifact snapshot)
        project (///metadata/artifact.read repository artifact)
        _ (|> project
              (set@ #///metadata/artifact.versions (list version_template))
diff --git a/stdlib/source/program/aedifex/format.lux b/stdlib/source/program/aedifex/format.lux
index 6fcbb2db7..7778e7641 100644
--- a/stdlib/source/program/aedifex/format.lux
+++ b/stdlib/source/program/aedifex/format.lux
@@ -140,7 +140,7 @@
       (..on_set "repositories" (get@ #/.repositories value) code.text)
       (..on_set "dependencies" (get@ #/.dependencies value) ..dependency)
       (..on_set "sources" (get@ #/.sources value) code.text)
-      (..on_maybe "target" (get@ #/.target value) code.text)
+      (dictionary.put "target" (code.text (get@ #/.target value)))
       (..on_maybe "program" (get@ #/.program value) code.text)
       (..on_maybe "test" (get@ #/.test value) code.text)
       (..on_dictionary "deploy_repositories" (get@ #/.deploy_repositories value) code.text code.text)
diff --git a/stdlib/source/program/aedifex/parser.lux b/stdlib/source/program/aedifex/parser.lux
index 3c1b4144a..60e491dac 100644
--- a/stdlib/source/program/aedifex/parser.lux
+++ b/stdlib/source/program/aedifex/parser.lux
@@ -200,9 +200,10 @@
                        (|> (..plural input "sources" ..source)
                            (\ ! map (set.from_list text.hash))
                            (<>.default (set.from_list text.hash (list /.default_source)))))
-           ^target (: (Parser (Maybe /.Target))
-                      (<>.maybe
-                       (..singular input "target" ..target)))
+           ^target (: (Parser /.Target)
+                      (|> ..target
+                          (..singular input "target")
+                          (<>.default /.default_target)))
            ^program (: (Parser (Maybe Module))
                        (<>.maybe
                         (..singular input "program" ..module)))
diff --git a/stdlib/source/program/aedifex/pom.lux b/stdlib/source/program/aedifex/pom.lux
index f105f07b6..0d468d5f2 100644
--- a/stdlib/source/program/aedifex/pom.lux
+++ b/stdlib/source/program/aedifex/pom.lux
@@ -30,6 +30,9 @@
 
 (def: project_tag "project")
 (def: dependencies_tag "dependencies")
+(def: repositories_tag "repositories")
+(def: repository_tag "repository")
+(def: url_tag "url")
 (def: group_tag "groupId")
 (def: artifact_tag "artifactId")
 (def: version_tag "version")
@@ -63,15 +66,15 @@
 (def: (license [name url distribution])
   (-> /.License XML)
   (|> (list (..property "name" name)
-            (..property "url" url)
+            (..property ..url_tag url)
             (..distribution distribution))
       (#_.Node ["" "license"] _.attributes)))
 
 (def: repository
   (-> Address XML)
-  (|>> (..property "url")
+  (|>> (..property ..url_tag)
        list
-       (#_.Node ["" "repository"] _.attributes)))
+       (#_.Node ["" ..repository_tag] _.attributes)))
 
 (def: (dependency value)
   (-> Dependency XML)
@@ -87,14 +90,14 @@
 (comment
   (def: scm
     (-> /.SCM XML)
-    (|>> (..property "url")
+    (|>> (..property ..url_tag)
          list
          (#_.Node ["" "scm"] _.attributes)))
 
   (def: (organization [name url])
     (-> /.Organization XML)
     (|> (list (..property "name" name)
-              (..property "url" url))
+              (..property ..url_tag url))
         (#_.Node ["" "organization"] _.attributes)))
 
   (def: (developer_organization [name url])
@@ -120,7 +123,7 @@
   (def: (info value)
     (-> /.Info (List XML))
     ($_ list\compose
-        (|> value (get@ #/.url) (maybe\map (..property "url")) maybe.to_list)
+        (|> value (get@ #/.url) (maybe\map (..property ..url_tag)) maybe.to_list)
         (|> value (get@ #/.description) (maybe\map (..property "description")) maybe.to_list)
         (|> value (get@ #/.licenses) (list\map ..license) (..group "licenses") list)
         (|> value (get@ #/.scm) (maybe\map ..scm) maybe.to_list)
@@ -178,6 +181,21 @@
     [_ (<xml>.node ["" ..dependencies_tag])]
     (<xml>.children (<>.some (..parse_dependency own_version parent_version)))))
 
+(def: parse_repository
+  (Parser Address)
+  (do {! <>.monad}
+    [_ (<xml>.node ["" ..repository_tag])]
+    (<xml>.children
+     (do !
+       [_ (<xml>.node ["" ..url_tag])]
+       (<xml>.children <xml>.text)))))
+
+(def: parse_repositories
+  (Parser (List Address))
+  (do {! <>.monad}
+    [_ (<xml>.node ["" ..repositories_tag])]
+    (<xml>.children (<>.some ..parse_repository))))
+
 (def: own_version
   (Parser Text)
   (do <>.monad
@@ -201,7 +219,12 @@
        [dependencies (|> (..parse_dependencies own_version parent_version)
                          <xml>.somewhere
                          (<>.default (list)))
+        repositories (|> ..parse_repositories
+                         <xml>.somewhere
+                         (<>.default (list)))
         _ (<>.some <xml>.ignore)]
        (wrap (|> (\ /.monoid identity)
                  (update@ #/.dependencies (function (_ empty)
-                                            (list\fold set.add empty dependencies)))))))))
+                                            (list\fold set.add empty dependencies)))
+                 (update@ #/.repositories (function (_ empty)
+                                            (list\fold set.add empty repositories)))))))))
diff --git a/stdlib/source/program/aedifex/profile.lux b/stdlib/source/program/aedifex/profile.lux
index 592e221fd..98eb1c43e 100644
--- a/stdlib/source/program/aedifex/profile.lux
+++ b/stdlib/source/program/aedifex/profile.lux
@@ -8,7 +8,7 @@
    [data
     ["." product]
     ["." maybe ("#\." monoid)]
-    ["." text]
+    ["." text ("#\." equivalence)]
     [collection
      ["." dictionary (#+ Dictionary)]
      ["." list ("#\." monoid)]
@@ -150,7 +150,7 @@
    #repositories (Set Address)
    #dependencies (Set dependency.Dependency)
    #sources (Set Source)
-   #target (Maybe Target)
+   #target Target
    #program (Maybe Module)
    #test (Maybe Module)
    #deploy_repositories (Dictionary Text Address)})
@@ -171,7 +171,7 @@
       ## #sources
       set.equivalence
       ## #target
-      (maybe.equivalence text.equivalence)
+      text.equivalence
       ## #program
       (maybe.equivalence text.equivalence)
       ## #test
@@ -189,7 +189,7 @@
      #repositories (set.new text.hash)
      #dependencies (set.new dependency.hash)
      #sources (set.new text.hash)
-     #target #.None
+     #target ..default_target
      #program #.None
      #test #.None
      #deploy_repositories (dictionary.new text.hash)})
@@ -201,7 +201,9 @@
      #repositories (set.union (get@ #repositories baseline) (get@ #repositories override))
      #dependencies (set.union (get@ #dependencies baseline) (get@ #dependencies override))
      #sources (set.union (get@ #sources baseline) (get@ #sources override))
-     #target (maybe\compose (get@ #target override) (get@ #target baseline))
+     #target (if (text\= ..default_target (get@ #target baseline))
+               (get@ #target override)
+               (get@ #target baseline))
      #program (maybe\compose (get@ #program override) (get@ #program baseline))
      #test (maybe\compose (get@ #test override) (get@ #test baseline))
      #deploy_repositories (dictionary.merge (get@ #deploy_repositories override) (get@ #deploy_repositories baseline))}))
diff --git a/stdlib/source/program/compositor.lux b/stdlib/source/program/compositor.lux
index a6b85ccf0..557e9d22a 100644
--- a/stdlib/source/program/compositor.lux
+++ b/stdlib/source/program/compositor.lux
@@ -20,6 +20,8 @@
     [collection
      ["." dictionary]
      ["." row (#+ Row)]]]
+   [time
+    ["." instant]]
    ["." world #_
     ["." file (#+ File Path)]
     ["#/." program]
@@ -71,6 +73,18 @@
       (#try.Success output)
       (wrap output))))
 
+(def: (timed process)
+  (All [a]
+    (-> (Promise (Try a)) (Promise (Try a))))
+  (do promise.monad
+    [#let [start (io.run instant.now)]
+     output process
+     #let [_ ("lux io log" (|> (io.run instant.now)
+                               (instant.span start)
+                               %.duration
+                               (format "Duration: ")))]]
+    (wrap output)))
+
 (def: (package! monad file_system [packager package] static archive context)
   (All [!] (-> (Monad !) (file.System !) [Packager Path] Static Archive Context (! (Try Any))))
   (for {@.old
@@ -132,6 +146,7 @@
       (case service
         (#/cli.Compilation compilation)
         (<| (or_crash! "Compilation failed:")
+            ..timed
             (do (try.with promise.monad)
               [#let [[compilation_sources compilation_libraries compilation_target compilation_module] compilation]
                import (/import.import (get@ #platform.&file_system platform) compilation_libraries)
diff --git a/stdlib/source/spec/lux/world/program.lux b/stdlib/source/spec/lux/world/program.lux
index f7f848ed3..939445169 100644
--- a/stdlib/source/spec/lux/world/program.lux
+++ b/stdlib/source/spec/lux/world/program.lux
@@ -21,8 +21,8 @@
   (-> (/.Program Promise) Test)
   (do random.monad
     [exit random.int]
-    (wrap (do promise.monad
-            [environment (\ subject environment [])
+    (wrap (do {! promise.monad}
+            [environment (/.environment ! subject)
              home (\ subject home [])
              directory (\ subject directory [])]
             (_.cover' [/.Program]
diff --git a/stdlib/source/test/aedifex.lux b/stdlib/source/test/aedifex.lux
index b7d0d29d9..8757242c5 100644
--- a/stdlib/source/test/aedifex.lux
+++ b/stdlib/source/test/aedifex.lux
@@ -15,9 +15,9 @@
    ["#." input]
    ["#." local]
    ["#." metadata]
-   ## ["#." package]
-   ## ["#." profile]
-   ## ["#." project]
+   ["#." package]
+   ["#." profile]
+   ["#." project]
    ## ["#." parser]
    ## ["#." pom]
    ## ["#." repository]
@@ -43,10 +43,10 @@
       /input.test
       /local.test
       /metadata.test
+      /package.test
+      /profile.test
+      /project.test
       
-      ## /package.test
-      ## /profile.test
-      ## /project.test
       ## /parser.test
       ## /pom.test
       ## /repository.test
diff --git a/stdlib/source/test/aedifex/command/auto.lux b/stdlib/source/test/aedifex/command/auto.lux
index c23519bcc..7ef74d2c0 100644
--- a/stdlib/source/test/aedifex/command/auto.lux
+++ b/stdlib/source/test/aedifex/command/auto.lux
@@ -14,7 +14,9 @@
      ["!" capability]]]
    [data
     ["." text
-     ["%" format (#+ format)]]
+     ["%" format (#+ format)]
+     [encoding
+      ["." utf8]]]
     [collection
      ["." dictionary]
      ["." set]
@@ -27,7 +29,7 @@
     [console (#+ Console)]
     ["." shell (#+ Shell)]
     ["." program (#+ Program)]
-    ["." file (#+ Path)
+    ["." file (#+ Path File)
      ["." watch]]]]
   ["." // #_
    ["@." version]
@@ -47,28 +49,22 @@
       ["#." dependency
        ["#/." resolution (#+ Resolution)]]]]]})
 
-(def: (command end_signal dummy_files)
-  (-> Text (List Path)
-      [(Atom [Nat (List Path)])
+(def: (command expected_runs end_signal dummy_file)
+  (-> Nat Text (File Promise)
+      [(Atom Nat)
        (-> (Console Promise) (Program Promise) (file.System Promise) (Shell Promise) Resolution (Command Any))])
-  (let [@runs (: (Atom [Nat (List Path)])
-                 (atom.atom [0 dummy_files]))]
+  (let [@runs (: (Atom Nat)
+                 (atom.atom 0))]
     [@runs
      (function (_ console program fs shell resolution profile)
        (do {! promise.monad}
-         [[_ [runs remaining_files]] (promise.future
-                                      (atom.update (function (_ [runs remaining_files])
-                                                     [(inc runs) remaining_files])
-                                                   @runs))]
-         (case remaining_files
-           #.Nil
+         [[_ actual_runs] (promise.future (atom.update inc @runs))]
+         (if (n.= expected_runs actual_runs)
            (wrap (#try.Failure end_signal))
-           
-           (#.Cons head tail)
            (do (try.with !)
-             [_ (!.use (\ fs create_file) [head])]
+             [_ (!.use (\ dummy_file over_write) (\ utf8.codec encode (%.nat actual_runs)))]
              (do !
-               [_ (promise.future (atom.write [runs tail] @runs))]
+               [_ (promise.future (atom.write actual_runs @runs))]
                (wrap (#try.Success [])))))))]))
 
 (def: #export test
@@ -85,7 +81,7 @@
          #let [empty_profile (: Profile
                                 (\ ///.monoid identity))
                with_target (: (-> Profile Profile)
-                              (set@ #///.target (#.Some target)))
+                              (set@ #///.target target))
                with_program (: (-> Profile Profile)
                                (set@ #///.program (#.Some program)))
                
@@ -98,15 +94,14 @@
          working_directory (random.ascii/alpha 5)
          
          expected_runs (\ ! map (|>> (n.% 10) (n.max 2)) random.nat)
-         dummy_files (|> (random.ascii/alpha 5)
-                         (random.set text.hash (dec expected_runs))
-                         (\ ! map (|>> set.to_list (list\map (|>> (format source /))))))
+         dummy_path (\ ! map (|>> (format source /)) (random.ascii/alpha 5))
          resolution @build.resolution]
         ($_ _.and
             (wrap (do promise.monad
                     [verdict (do ///action.monad
-                               [#let [[@runs command] (..command end_signal dummy_files)]
-                                _ (!.use (\ fs create_directory) [source])
+                               [_ (!.use (\ fs create_directory) [source])
+                                dummy_file (!.use (\ fs create_file) [dummy_path])
+                                #let [[@runs command] (..command expected_runs end_signal dummy_file)]
                                 _ (\ watcher poll [])]
                                (do promise.monad
                                  [outcome ((/.do! 1 watcher command)
@@ -116,7 +111,7 @@
                                            (shell.async (@build.good_shell []))
                                            resolution
                                            profile)
-                                  [actual_runs _] (promise.future (atom.read @runs))]
+                                  actual_runs (promise.future (atom.read @runs))]
                                  (wrap (#try.Success (and (n.= expected_runs actual_runs)
                                                           (case outcome
                                                             (#try.Failure error)
diff --git a/stdlib/source/test/aedifex/command/build.lux b/stdlib/source/test/aedifex/command/build.lux
index 234343fea..7fd8c3eb3 100644
--- a/stdlib/source/test/aedifex/command/build.lux
+++ b/stdlib/source/test/aedifex/command/build.lux
@@ -109,7 +109,7 @@
          #let [empty_profile (: Profile
                                 (\ ///.monoid identity))
                with_target (: (-> Profile Profile)
-                              (set@ #///.target (#.Some target)))
+                              (set@ #///.target target))
                with_program (: (-> Profile Profile)
                                (set@ #///.program (#.Some program)))
                
@@ -128,16 +128,6 @@
                                 (#try.Failure error)
                                 (exception.match? /.no_specified_program error)))))
             (wrap (do promise.monad
-                    [outcome (/.do! (@version.echo "") (program.async (program.mock environment.empty home working_directory)) fs shell ///dependency/resolution.empty
-                                    (with_program empty_profile))]
-                    (_.cover' [/.no_specified_target]
-                              (case outcome
-                                (#try.Success _)
-                                false
-
-                                (#try.Failure error)
-                                (exception.match? /.no_specified_target error)))))
-            (wrap (do promise.monad
                     [outcome (/.do! (@version.echo "") (program.async (program.mock environment.empty home working_directory)) fs shell ///dependency/resolution.empty profile)]
                     (_.cover' [/.Compiler /.no_available_compiler]
                               (case outcome
diff --git a/stdlib/source/test/aedifex/command/clean.lux b/stdlib/source/test/aedifex/command/clean.lux
index d98473259..705cca7f2 100644
--- a/stdlib/source/test/aedifex/command/clean.lux
+++ b/stdlib/source/test/aedifex/command/clean.lux
@@ -99,35 +99,25 @@
          sub_files (..files (format sub_path /))
 
          dummy @profile.random]
-        ($_ _.and
-            (wrap (do promise.monad
-                    [#let [console (@version.echo "")]
-                     verdict (do {! (try.with promise.monad)}
-                               [_ (/.do! console fs (set@ #///.target #.None dummy))]
-                               (\ ! map (text\= /.failure)
-                                  (!.use (\ console read_line) [])))]
-                    (_.cover' [/.failure]
-                              (try.default false verdict))))
-            (wrap (do promise.monad
-                    [#let [console (@version.echo "")]
-                     verdict (do {! (try.with promise.monad)}
-                               [_ (..create_directory! fs target_path direct_files)
-                                _ (..create_directory! fs sub_path sub_files)
-                                context_exists!/pre (..directory_exists? fs context)
-                                target_exists!/pre (..assets_exist? fs target_path direct_files)
-                                sub_exists!/pre (..assets_exist? fs sub_path sub_files)
-                                _ (/.do! console fs (set@ #///.target (#.Some target_path) dummy))
-                                context_exists!/post (..directory_exists? fs context)
-                                target_exists!/post (..assets_exist? fs target_path direct_files)
-                                sub_exists!/post (..assets_exist? fs sub_path sub_files)
-                                logging (!.use (\ console read_line) [])]
-                               (wrap (and (and context_exists!/pre
-                                               context_exists!/post)
-                                          (and target_exists!/pre
-                                               (not target_exists!/post))
-                                          (and sub_exists!/pre
-                                               (not sub_exists!/post))
-                                          (text\= /.success logging))))]
-                    (_.cover' [/.do! /.success]
-                              (try.default false verdict))))
-            ))))
+        (wrap (do promise.monad
+                [#let [console (@version.echo "")]
+                 verdict (do {! (try.with promise.monad)}
+                           [_ (..create_directory! fs target_path direct_files)
+                            _ (..create_directory! fs sub_path sub_files)
+                            context_exists!/pre (..directory_exists? fs context)
+                            target_exists!/pre (..assets_exist? fs target_path direct_files)
+                            sub_exists!/pre (..assets_exist? fs sub_path sub_files)
+                            _ (/.do! console fs (set@ #///.target target_path dummy))
+                            context_exists!/post (..directory_exists? fs context)
+                            target_exists!/post (..assets_exist? fs target_path direct_files)
+                            sub_exists!/post (..assets_exist? fs sub_path sub_files)
+                            logging (!.use (\ console read_line) [])]
+                           (wrap (and (and context_exists!/pre
+                                           context_exists!/post)
+                                      (and target_exists!/pre
+                                           (not target_exists!/post))
+                                      (and sub_exists!/pre
+                                           (not sub_exists!/post))
+                                      (text\= (/.success target_path) logging))))]
+                (_.cover' [/.do! /.success]
+                          (try.default false verdict)))))))
diff --git a/stdlib/source/test/aedifex/command/deploy.lux b/stdlib/source/test/aedifex/command/deploy.lux
index cc99f2e48..7e1bf166e 100644
--- a/stdlib/source/test/aedifex/command/deploy.lux
+++ b/stdlib/source/test/aedifex/command/deploy.lux
@@ -123,7 +123,7 @@
                                             (\ ///hash.md5_codec decode actual_md5)))
 
                             #let [succeeded!
-                                  (text\= //clean.success logging)
+                                  (text\= /.success logging)
 
                                   deployed_library!
                                   (\ binary.equivalence =
@@ -149,5 +149,5 @@
                                       deployed_pom!
                                       deployed_sha-1!
                                       deployed_md5!)))]
-                (_.cover' [/.do!]
+                (_.cover' [/.do! /.success]
                           (try.default false verdict)))))))
diff --git a/stdlib/source/test/aedifex/command/deps.lux b/stdlib/source/test/aedifex/command/deps.lux
index 8b5e3820e..2b4898dd3 100644
--- a/stdlib/source/test/aedifex/command/deps.lux
+++ b/stdlib/source/test/aedifex/command/deps.lux
@@ -107,9 +107,6 @@
                                      (set@ #///.dependencies (set.from_list ///dependency.hash (list dependee depender)))
                                      (/.do! console local (list (///repository.mock ($///dependency/resolution.single depender_artifact depender_package)
                                                                                     []))))
-                            logging! (\ ///action.monad map
-                                        (text\= //clean.success)
-                                        (!.use (\ console read_line) []))
 
                             #let [had_dependee_before!
                                   (set.member? pre dependee_artifact)
@@ -122,9 +119,7 @@
                                   
                                   had_depender_after!
                                   (dictionary.key? post depender)]]
-                           (wrap (and logging!
-
-                                      had_dependee_before!
+                           (wrap (and had_dependee_before!
                                       lacked_depender_before!
                                       
                                       had_dependee_after!
diff --git a/stdlib/source/test/aedifex/command/install.lux b/stdlib/source/test/aedifex/command/install.lux
index 33ee7192d..8096fc2b2 100644
--- a/stdlib/source/test/aedifex/command/install.lux
+++ b/stdlib/source/test/aedifex/command/install.lux
@@ -92,7 +92,7 @@
                                       library_path (format artifact_path ///artifact/extension.lux_library)
                                       pom_path (format artifact_path ///artifact/extension.pom)]
 
-                                #let [succeeded! (text\= //clean.success logging)]
+                                #let [succeeded! (text\= /.success logging)]
                                 library_exists! (\ promise.monad map
                                                    exception.return
                                                    (file.file_exists? promise.monad fs library_path))
@@ -102,7 +102,7 @@
                                (wrap (and succeeded!
                                           library_exists!
                                           pom_exists!)))]
-                    (_.cover' [/.do!]
+                    (_.cover' [/.do! /.success]
                               (try.default false verdict))))
             (wrap (do {! promise.monad}
                     [#let [fs (file.mock (\ file.default separator))
diff --git a/stdlib/source/test/aedifex/command/pom.lux b/stdlib/source/test/aedifex/command/pom.lux
index c368d5f84..f7f182225 100644
--- a/stdlib/source/test/aedifex/command/pom.lux
+++ b/stdlib/source/test/aedifex/command/pom.lux
@@ -54,7 +54,7 @@
                                 actual (!.use (\ file content) [])
 
                                 logging! (\ ///action.monad map
-                                            (text\= //clean.success)
+                                            (text\= /.success)
                                             (!.use (\ console read_line) []))
 
                                 #let [expected_path!
@@ -65,7 +65,7 @@
                                (wrap (and logging!
                                           expected_path!
                                           expected_content!)))]
-                    (_.cover' [/.do!]
+                    (_.cover' [/.do! /.success]
                               (try.default false verdict)))
                   
                   (#try.Failure error)
diff --git a/stdlib/source/test/aedifex/command/test.lux b/stdlib/source/test/aedifex/command/test.lux
index 6b7ba9324..291b31863 100644
--- a/stdlib/source/test/aedifex/command/test.lux
+++ b/stdlib/source/test/aedifex/command/test.lux
@@ -51,7 +51,7 @@
          #let [empty_profile (: Profile
                                 (\ ///.monoid identity))
                with_target (: (-> Profile Profile)
-                              (set@ #///.target (#.Some target)))
+                              (set@ #///.target target))
                with_test (: (-> Profile Profile)
                             (set@ #///.test (#.Some test)))
                
diff --git a/stdlib/source/test/aedifex/package.lux b/stdlib/source/test/aedifex/package.lux
index 960a75f21..132c51b38 100644
--- a/stdlib/source/test/aedifex/package.lux
+++ b/stdlib/source/test/aedifex/package.lux
@@ -2,13 +2,21 @@
   [lux #*
    ["_" test (#+ Test)]
    [abstract
-    [monad (#+ do)]]
+    [monad (#+ do)]
+    {[0 #spec]
+     [/
+      ["$." equivalence]]}]
    [control
     ["." try]
     [concurrency
      [promise (#+ Promise)]]]
    [data
-    ["." text]
+    ["." product]
+    ["." text
+     [encoding
+      ["." utf8]]]
+    [format
+     ["." xml (#+ XML)]]
     [collection
      ["." set (#+ Set)]]]
    [math
@@ -27,9 +35,11 @@
    ["." /
     ["/#" // #_
      ["#" profile]
-     ["#." dependency (#+ Dependency)]
      ["#." pom]
-     ["#." hash]]]})
+     [dependency
+      ["#." status]]
+     [repository
+      ["#." origin]]]]})
 
 (def: #export random
   (Random [//.Profile /.Package])
@@ -51,15 +61,37 @@
       (do {! random.monad}
         [[profile package] ..random]
         ($_ _.and
+            (_.for [/.equivalence]
+                   ($equivalence.spec /.equivalence (\ ! map product.right ..random)))
+            
+            (_.cover [/.local?]
+                     (/.local? (set@ #/.origin (#//origin.Local "~/yolo") package)))
+            (_.cover [/.remote?]
+                     (/.remote? (set@ #/.origin (#//origin.Remote "https://example.com") package)))
             (_.cover [/.local]
-                     false
-                     ## (and (\ //hash.equivalence =
-                     ##         (//hash.sha-1 (get@ #/.library package))
-                     ##         (get@ #/.sha-1 package))
-                     ##      (\ //hash.equivalence =
-                     ##         (//hash.md5 (get@ #/.library package))
-                     ##         (get@ #/.md5 package)))
-                     )
+                     (let [expected_pom (|> package (get@ #/.pom) product.left)
+                           expected_library (|> package (get@ #/.library) product.left)
+
+                           local (/.local expected_pom expected_library)
+
+                           [actual_pom binary_pom pom_status] (get@ #/.pom local)
+                           [actual_library library_status] (get@ #/.library local)]
+                       (and (case (get@ #/.origin local)
+                              (#//origin.Local "") true
+                              _ false)
+                            (and (is? expected_library actual_library)
+                                 (case library_status
+                                   #//status.Unverified true
+                                   _ false))
+                            (and (is? expected_pom actual_pom)
+                                 (|> (do try.monad
+                                       [xml_pom (\ utf8.codec decode binary_pom)
+                                        decoded_pom (\ xml.codec decode xml_pom)]
+                                       (wrap (\ xml.equivalence = actual_pom decoded_pom)))
+                                     (try.default false))
+                                 (case pom_status
+                                   #//status.Unverified true
+                                   _ false)))))
             (_.cover [/.dependencies]
                      (let [expected (get@ #//.dependencies profile)]
                        (case (/.dependencies package)
@@ -68,4 +100,12 @@
                          
                          (#try.Failure error)
                          false)))
+            (_.cover [/.repositories]
+                     (let [expected (get@ #//.repositories profile)]
+                       (case (/.repositories package)
+                         (#try.Success actual)
+                         (\ set.equivalence = expected actual)
+                         
+                         (#try.Failure error)
+                         false)))
             ))))
diff --git a/stdlib/source/test/aedifex/profile.lux b/stdlib/source/test/aedifex/profile.lux
index ea03a1e92..3410255f5 100644
--- a/stdlib/source/test/aedifex/profile.lux
+++ b/stdlib/source/test/aedifex/profile.lux
@@ -125,7 +125,7 @@
       (..set_of text.hash ..repository)
       (..set_of //dependency.hash @dependency.random)
       (..set_of text.hash ..source)
-      (random.maybe ..target)
+      ..target
       (random.maybe (random.ascii/alpha 1))
       (random.maybe (random.ascii/alpha 1))
       (..dictionary_of text.hash (random.ascii/alpha 1) ..repository)
diff --git a/stdlib/source/test/lux/type/check.lux b/stdlib/source/test/lux/type/check.lux
index 45e648b9c..e6e0f4b16 100644
--- a/stdlib/source/test/lux/type/check.lux
+++ b/stdlib/source/test/lux/type/check.lux
@@ -1,20 +1,29 @@
 (.module:
   [lux (#- type)
-   ["%" data/text/format (#+ format)]
    ["_" test (#+ Test)]
    [abstract
-    ["." monad (#+ do)]]
+    ["." monad (#+ do)]
+    {[0 #spec]
+     [/
+      ["$." functor (#+ Injection Comparison)]
+      ["$." apply]
+      ["$." monad]]}]
    [control
-    [pipe (#+ case>)]]
+    [pipe (#+ case>)]
+    ["." function]
+    ["." try]
+    ["." exception (#+ exception:)]]
    [data
+    ["." bit ("#\." equivalence)]
     ["." product]
     ["." maybe]
-    ["." text ("#\." equivalence)]
+    ["." text ("#\." equivalence)
+     ["%" format (#+ format)]]
     [collection
-     ["." list ("#\." functor)]
+     ["." list ("#\." functor monoid)]
      ["." set]]]
    [math
-    ["." random (#+ Random)]
+    ["." random (#+ Random) ("#\." monad)]
     [number
      ["n" nat]]]
    ["." type ("#\." equivalence)]]
@@ -34,27 +43,26 @@
   (-> Nat (Random Type))
   (random.rec
    (function (_ recur)
-     (let [(^open "R\.") random.monad
-           pairG (random.and recur recur)
-           quantifiedG (random.and (R\wrap (list)) (type' (inc num_vars)))
-           random_pair (random.either (random.either (R\map (|>> #.Sum) pairG)
-                                                     (R\map (|>> #.Product) pairG))
-                                      (random.either (R\map (|>> #.Function) pairG)
-                                                     (R\map (|>> #.Apply) pairG)))
-           random_id (let [random_id (random.either (R\map (|>> #.Var) random.nat)
-                                                    (R\map (|>> #.Ex) random.nat))]
+     (let [pairG (random.and recur recur)
+           quantifiedG (random.and (random\wrap (list)) (type' (inc num_vars)))
+           random_pair (random.either (random.either (random\map (|>> #.Sum) pairG)
+                                                     (random\map (|>> #.Product) pairG))
+                                      (random.either (random\map (|>> #.Function) pairG)
+                                                     (random\map (|>> #.Apply) pairG)))
+           random_id (let [random_id (random.either (random\map (|>> #.Var) random.nat)
+                                                    (random\map (|>> #.Ex) random.nat))]
                        (case num_vars
                          0 random_id
-                         _ (random.either (R\map (|>> (n.% num_vars) (n.* 2) inc #.Parameter) random.nat)
+                         _ (random.either (random\map (|>> (n.% num_vars) (n.* 2) inc #.Parameter) random.nat)
                                           random_id)))
-           random_quantified (random.either (R\map (|>> #.UnivQ) quantifiedG)
-                                            (R\map (|>> #.ExQ) quantifiedG))]
+           random_quantified (random.either (random\map (|>> #.UnivQ) quantifiedG)
+                                            (random\map (|>> #.ExQ) quantifiedG))]
        ($_ random.either
-           (R\map (|>> #.Primitive) (random.and ..short (R\wrap (list))))
+           (random\map (|>> #.Primitive) (random.and ..short (random\wrap (list))))
            random_pair
            random_id
            random_quantified
-           (R\map (|>> #.Named) (random.and ..name (type' 0)))
+           (random\map (|>> #.Named) (random.and ..name (type' 0)))
            )))))
 
 (def: type
@@ -81,178 +89,633 @@
     _
     #0))
 
-(def: (type_checks? input)
-  (-> (/.Check []) Bit)
-  (case (/.run /.fresh_context input)
-    (#.Right [])
-    #1
+(def: injection
+  (Injection (All [a] (/.Check a)))
+  (\ /.monad wrap))
 
-    (#.Left error)
-    #0))
+(def: comparison
+  (Comparison (All [a] (/.Check a)))
+  (function (_ == left right)
+    (case [(/.run /.fresh_context left) (/.run /.fresh_context right)]
+      [(#try.Success left) (#try.Success right)]
+      (== left right)
 
-(def: (build_ring num_connections)
-  (-> Nat (/.Check [[Nat Type] (List [Nat Type]) [Nat Type]]))
-  (do {! /.monad}
-    [[head_id head_type] /.var
-     ids+types (monad.seq ! (list.repeat num_connections /.var))
-     [tail_id tail_type] (monad.fold ! (function (_ [tail_id tail_type] [_head_id _head_type])
-                                         (do !
-                                           [_ (/.check head_type tail_type)]
-                                           (wrap [tail_id tail_type])))
-                                     [head_id head_type]
-                                     ids+types)]
-    (wrap [[head_id head_type] ids+types [tail_id tail_type]])))
+      _
+      false)))
 
-(def: #export test
+(def: polymorphism
+  Test
+  ($_ _.and
+      (_.for [/.functor]
+             ($functor.spec ..injection ..comparison /.functor))
+      (_.for [/.apply]
+             ($apply.spec ..injection ..comparison /.apply))
+      (_.for [/.monad]
+             ($monad.spec ..injection ..comparison /.monad))
+      ))
+
+(exception: yolo)
+
+(def: error_handling
   Test
-  (<| (_.context (%.name (name_of /._)))
+  ($_ _.and
+      (do random.monad
+        [expected (random.ascii/upper 10)]
+        (_.cover [/.fail]
+                 (case (/.run /.fresh_context
+                              (: (/.Check Any)
+                                 (/.fail expected)))
+                   (#try.Success _) false
+                   (#try.Failure actual) (is? expected actual))))
+      (do random.monad
+        [expected (random.ascii/upper 10)]
+        (_.cover [/.assert]
+                 (and (case (/.run /.fresh_context
+                                   (: (/.Check Any)
+                                      (/.assert expected true)))
+                        (#try.Success _) true
+                        (#try.Failure actual) false)
+                      (case (/.run /.fresh_context (/.assert expected false))
+                        (#try.Success _) false
+                        (#try.Failure actual) (is? expected actual)))))
+      (_.cover [/.throw]
+               (case (/.run /.fresh_context
+                            (: (/.Check Any)
+                               (/.throw ..yolo [])))
+                 (#try.Success _) false
+                 (#try.Failure error) (exception.match? ..yolo error)))
+      ))
+
+(def: var
+  Test
+  (<| (_.for [/.Var])
       ($_ _.and
+          (_.cover [/.var]
+                   (case (/.run /.fresh_context
+                                (do /.monad
+                                  [[var_id var_type] /.var]
+                                  (wrap (type\= var_type (#.Var var_id)))))
+                     (#try.Success verdict) verdict
+                     (#try.Failure error) false))
+          (do random.monad
+            [nominal (random.ascii/upper 10)]
+            (_.cover [/.bind]
+                     (case (/.run /.fresh_context
+                                  (do /.monad
+                                    [[var_id var_type] /.var
+                                     _ (/.bind (#.Primitive nominal (list))
+                                               var_id)]
+                                    (wrap true)))
+                       (#try.Success _) true
+                       (#try.Failure error) false)))
           (do random.monad
-            [sample (random.filter ..valid_type? ..type)]
-            ($_ _.and
-                (_.test "Any is the super-type of everything."
-                        (/.checks? Any sample))
-                (_.test "Nothing is the sub-type of everything."
-                        (/.checks? sample Nothing))
-                ))
-          ($_ _.and
-              (_.test "Any and Nothing match themselves."
-                      (and (/.checks? Nothing Nothing)
-                           (/.checks? Any Any)))
-              (_.test "Existential types only match with themselves."
-                      (and (type_checks? (do /.monad
-                                           [[_ exT] /.existential]
-                                           (/.check exT exT)))
-                           (not (type_checks? (do /.monad
-                                                [[_ exTL] /.existential
-                                                 [_ exTR] /.existential]
-                                                (/.check exTL exTR))))))
-              (_.test "Names do not affect type-checking."
-                      (and (type_checks? (do /.monad
-                                           [[_ exT] /.existential]
-                                           (/.check (#.Named ["module" "name"] exT)
-                                                    exT)))
-                           (type_checks? (do /.monad
-                                           [[_ exT] /.existential]
-                                           (/.check exT
-                                                    (#.Named ["module" "name"] exT))))
-                           (type_checks? (do /.monad
-                                           [[_ exT] /.existential]
-                                           (/.check (#.Named ["module" "name"] exT)
-                                                    (#.Named ["module" "name"] exT))))))
-              (_.test "Functions are covariant on inputs and contravariant on outputs."
-                      (and (/.checks? (#.Function Nothing Any)
-                                      (#.Function Any Nothing))
-                           (not (/.checks? (#.Function Any Nothing)
-                                           (#.Function Nothing Any)))))
-              )
+            [nominal (random.ascii/upper 10)]
+            (_.cover [/.bound?]
+                     (and (|> (do /.monad
+                                [[var_id var_type] /.var
+                                 pre (/.bound? var_id)
+                                 _ (/.bind (#.Primitive nominal (list))
+                                           var_id)
+                                 post (/.bound? var_id)]
+                                (wrap (and (not pre)
+                                           post)))
+                              (/.run /.fresh_context)
+                              (try.default false))
+                          (|> (do /.monad
+                                [[var_id var/0] /.var
+                                 pre (/.bound? var_id)
+                                 [_ var/1] /.var
+                                 _ (/.check var/0 var/1)
+                                 post (/.bound? var_id)]
+                                (wrap (and (not pre)
+                                           (not post))))
+                              (/.run /.fresh_context)
+                              (try.default false)))))
           (do random.monad
-            [meta ..type
-             data ..type]
-            (_.test "Can type-check type application."
-                    (and (/.checks? (|> Ann (#.Apply meta) (#.Apply data))
-                                    (type.tuple (list meta data)))
-                         (/.checks? (type.tuple (list meta data))
-                                    (|> Ann (#.Apply meta) (#.Apply data))))))
+            [nominal (random.ascii/upper 10)]
+            (_.cover [/.cannot_rebind_var]
+                     (case (/.run /.fresh_context
+                                  (do /.monad
+                                    [[var_id var_type] /.var
+                                     _ (/.bind (#.Primitive nominal (list))
+                                               var_id)]
+                                    (/.bind (#.Primitive nominal (list))
+                                            var_id)))
+                       (#try.Success _)
+                       false
+                       
+                       (#try.Failure error)
+                       (exception.match? /.cannot_rebind_var error))))
+          (do random.monad
+            [nominal (random.ascii/upper 10)
+             var_id random.nat]
+            (_.cover [/.unknown_type_var]
+                     (case (/.run /.fresh_context
+                                  (/.bind (#.Primitive nominal (list))
+                                          var_id))
+                       (#try.Success _)
+                       false
+                       
+                       (#try.Failure error)
+                       (exception.match? /.unknown_type_var error))))
+          (do random.monad
+            [nominal (random.ascii/upper 10)
+             #let [expected (#.Primitive nominal (list))]]
+            (_.cover [/.read]
+                     (and (|> (do /.monad
+                                [[var_id var_type] /.var]
+                                (/.read var_id))
+                              (/.run /.fresh_context)
+                              (case> (#try.Success #.None) true
+                                     _ false))
+                          (|> (do /.monad
+                                [[var_id var/0] /.var
+                                 [_ var/1] /.var
+                                 _ (/.check var/0 var/1)]
+                                (/.read var_id))
+                              (/.run /.fresh_context)
+                              (case> (#try.Success #.None) true
+                                     _ false))
+                          (|> (do /.monad
+                                [[var_id var_type] /.var
+                                 _ (/.bind expected var_id)]
+                                (/.read var_id))
+                              (/.run /.fresh_context)
+                              (case> (#try.Success (#.Some actual))
+                                     (is? expected actual)
+                                     
+                                     _
+                                     false)))))
+          (do random.monad
+            [nominal (random.ascii/upper 10)
+             #let [expected (#.Primitive nominal (list))]]
+            (_.cover [/.read!]
+                     (case (/.run /.fresh_context
+                                  (do /.monad
+                                    [[var_id var_type] /.var
+                                     _ (/.bind expected var_id)]
+                                    (/.read! var_id)))
+                       (#try.Success actual)
+                       (is? expected actual)
+                       
+                       _
+                       false)))
+          (do random.monad
+            [nominal (random.ascii/upper 10)
+             #let [expected (#.Primitive nominal (list))]]
+            (_.cover [/.unbound_type_var]
+                     (case (/.run /.fresh_context
+                                  (do /.monad
+                                    [[var_id var_type] /.var]
+                                    (/.read! var_id)))
+                       (#try.Failure error)
+                       (exception.match? /.unbound_type_var error)
+
+                       _
+                       false)))
+          )))
+
+(def: context
+  Test
+  ($_ _.and
+      (_.cover [/.fresh_context]
+               (and (n.= 0 (get@ #.var_counter /.fresh_context))
+                    (n.= 0 (get@ #.ex_counter /.fresh_context))
+                    (list.empty? (get@ #.var_bindings /.fresh_context))))
+      (_.cover [/.context]
+               (and (case (/.run /.fresh_context /.context)
+                      (#try.Success actual)
+                      (is? /.fresh_context actual)
+                      
+                      (#try.Failure error)
+                      false)
+                    (case (/.run /.fresh_context
+                                 (do /.monad
+                                   [_ /.var]
+                                   /.context))
+                      (#try.Success actual)
+                      (and (n.= 1 (get@ #.var_counter actual))
+                           (n.= 0 (get@ #.ex_counter actual))
+                           (n.= 1 (list.size (get@ #.var_bindings actual))))
+                      
+                      (#try.Failure error)
+                      false)))
+      (_.cover [/.existential]
+               (case (/.run /.fresh_context
+                            (do /.monad
+                              [_ /.existential]
+                              /.context))
+                 (#try.Success actual)
+                 (and (n.= 0 (get@ #.var_counter actual))
+                      (n.= 1 (get@ #.ex_counter actual))
+                      (n.= 0 (list.size (get@ #.var_bindings actual))))
+                 
+                 (#try.Failure error)
+                 false))
+      ))
+
+(def: succeeds?
+  (All [a] (-> (/.Check a) Bit))
+  (|>> (/.run /.fresh_context)
+       (case> (#try.Success _)
+              true
+
+              (#try.Failure error)
+              false)))
+
+(def: fails?
+  (All [a] (-> (/.Check a) Bit))
+  (|>> ..succeeds?
+       not))
+
+(def: nominal
+  (Random Type)
+  (do random.monad
+    [name (random.ascii/upper 10)]
+    (wrap (#.Primitive name (list)))))
+
+(def: (non_twins = random)
+  (All [a] (-> (-> a a Bit) (Random a) (Random [a a])))
+  (do random.monad
+    [left random
+     right (random.filter (|>> (= left) not) random)]
+    (wrap [left right])))
+
+(type: Super
+  (Ex [sub] [Text sub]))
+
+(type: Sub
+  (Super Bit))
+
+(def: (handles_nominal_types! name/0 name/1 parameter/0 parameter/1)
+  (-> Text Text Type Type Bit)
+  (let [names_matter!
+        (and (..succeeds? (/.check (#.Primitive name/0 (list))
+                                   (#.Primitive name/0 (list))))
+             (..fails? (/.check (#.Primitive name/0 (list))
+                                (#.Primitive name/1 (list)))))
+
+        parameters_matter!
+        (and (..succeeds? (/.check (#.Primitive name/0 (list parameter/0))
+                                   (#.Primitive name/0 (list parameter/0))))
+             (..fails? (/.check (#.Primitive name/0 (list parameter/0))
+                                (#.Primitive name/0 (list parameter/1)))))
+
+        covariant_parameters!
+        (and (..succeeds? (/.check (#.Primitive name/0 (list Super))
+                                   (#.Primitive name/0 (list Sub))))
+             (..fails? (/.check (#.Primitive name/0 (list Sub))
+                                (#.Primitive name/0 (list Super)))))]
+    (and names_matter!
+         parameters_matter!
+         covariant_parameters!)))
+
+(template [<assertion> <combinator>]
+  [(def: (<assertion> name/0 name/1)
+     (-> Text Text Bit)
+     (let [pair/0 (<combinator> (#.Primitive name/0 (list)) (#.Primitive name/0 (list)))
+           pair/1 (<combinator> (#.Primitive name/1 (list)) (#.Primitive name/1 (list)))
+           
+           invariant!
+           (and (..succeeds? (/.check pair/0 pair/0))
+                (..fails? (/.check pair/0 pair/1)))
+
+           super_pair (<combinator> Super Super)
+           sub_pair (<combinator> Sub Sub)
+           
+           covariant!
+           (and (..succeeds? (/.check super_pair sub_pair))
+                (..fails? (/.check sub_pair super_pair)))]
+       (and invariant!
+            covariant!)))]
+
+  [handles_products! #.Product]
+  [handles_sums! #.Sum]
+  )
+
+(def: (handles_function_variance! nominal)
+  (-> Type Bit)
+  (let [functions_have_contravariant_inputs!
+        (..succeeds? (/.check (#.Function Sub nominal) (#.Function Super nominal)))
+        
+        functions_have_covariant_outputs!
+        (..succeeds? (/.check (#.Function nominal Super) (#.Function nominal Sub)))]
+    (and functions_have_contravariant_inputs!
+         functions_have_covariant_outputs!)))
+
+(def: (verdict check)
+  (All [_] (-> (/.Check _) (/.Check Bit)))
+  (function (_ context)
+    (#try.Success [context (case (check context)
+                             (#try.Success _)
+                             true
+
+                             (#try.Failure _)
+                             false)])))
+
+(def: (build_ring tail_size)
+  (-> Nat (/.Check [Type (List Type) Type]))
+  (do {! /.monad}
+    [[id/head var/head] /.var
+     var/tail+ (monad.map ! (function (_ _)
+                              (do !
+                                [[id/T var/tail] /.var]
+                                (wrap var/tail)))
+                          (list.repeat tail_size /.var))
+     var/last (monad.fold ! (function (_ var/next var/prev)
+                              (do !
+                                [_ (/.check var/prev var/next)]
+                                (wrap var/next)))
+                          var/head
+                          var/tail+)
+     _ (/.check var/last var/head)]
+    (wrap [var/head var/tail+ var/last])))
+
+(def: (handles_var_rings! tail_size nominal/0 nominal/1)
+  (-> Nat Type Type Bit)
+  (let [can_create_rings_of_variables!
+        (succeeds? (..build_ring tail_size))
+
+        can_bind_rings_of_variables!
+        (succeeds? (do {! /.monad}
+                     [[var/head var/tail+ var/last] (..build_ring tail_size)
+                      _ (/.check var/head nominal/0)
+                      failures (monad.map ! (|>> (/.check nominal/1) ..verdict) (list& var/head var/tail+))
+                      successes (monad.map ! (|>> (/.check nominal/0) ..verdict) (list& var/head var/tail+))]
+                     (/.assert "" (and (list.every? (bit\= false) failures)
+                                       (list.every? (bit\= true) successes)))))
+
+        can_merge_multiple_rings_of_variables!
+        (succeeds? (do {! /.monad}
+                     [[var/head/0 var/tail+/0 var/last/0] (..build_ring tail_size)
+                      [var/head/1 var/tail+/1 var/last/1] (..build_ring tail_size)
+                      _ (/.check var/head/0 var/head/1)
+                      _ (/.check var/head/0 nominal/0)
+                      #let [all_variables (list\compose (list& var/head/0 var/tail+/0)
+                                                        (list& var/head/1 var/tail+/1))]
+                      failures (monad.map ! (|>> (/.check nominal/1) ..verdict) all_variables)
+                      successes (monad.map ! (|>> (/.check nominal/0) ..verdict) all_variables)]
+                     (/.assert "" (and (list.every? (bit\= false) failures)
+                                       (list.every? (bit\= true) successes)))))]
+    (and can_create_rings_of_variables!
+         can_bind_rings_of_variables!
+         can_merge_multiple_rings_of_variables!)))
+
+(def: (handles_vars! nominal)
+  (-> Type Bit)
+  (let [vars_check_against_themselves!
+        (succeeds? (do /.monad
+                     [[id var] /.var]
+                     (/.check var var)))
+
+        can_bind_vars_by_checking_against_them!
+        (and (succeeds? (do /.monad
+                          [[id var] /.var]
+                          (/.check var nominal)))
+             (succeeds? (do /.monad
+                          [[id var] /.var]
+                          (/.check nominal var))))
+
+        cannot_rebind!
+        (fails? (do /.monad
+                  [[id var] /.var
+                   _ (/.check var nominal)]
+                  (/.check var ..Sub)))
+
+        bound_vars_check_against_their_bound_types!
+        (and (succeeds? (do /.monad
+                          [[id var] /.var
+                           _ (/.check var nominal)]
+                          (/.check nominal var)))
+             (succeeds? (do /.monad
+                          [[id var] /.var
+                           _ (/.check var ..Super)]
+                          (/.check var ..Sub)))
+             (succeeds? (do /.monad
+                          [[id var] /.var
+                           _ (/.check var ..Sub)]
+                          (/.check ..Super var)))
+
+             (fails? (do /.monad
+                       [[id var] /.var
+                        _ (/.check var ..Super)]
+                       (/.check ..Sub var)))
+             (fails? (do /.monad
+                       [[id var] /.var
+                        _ (/.check var ..Sub)]
+                       (/.check var ..Super))))]
+    (and vars_check_against_themselves!
+         can_bind_vars_by_checking_against_them!
+         cannot_rebind!
+         bound_vars_check_against_their_bound_types!)))
+
+(def: handles_existentials!
+  Bit
+  (let [existentials_always_match_themselves!
+        (..succeeds? (do /.monad
+                       [[_ single] /.existential]
+                       (/.check single single)))
+
+        existentials_never_match_each_other!
+        (..fails? (do /.monad
+                    [[_ left] /.existential
+                     [_ right] /.existential]
+                    (/.check left right)))]
+    (and existentials_always_match_themselves!
+         existentials_never_match_each_other!)))
+
+(def: (handles_quantification! nominal)
+  (-> Type Bit)
+  (let [universals_satisfy_themselves!
+        (..succeeds? (/.check (.type (All [a] (Maybe a)))
+                              (.type (All [a] (Maybe a)))))
+
+        existentials_satisfy_themselves!
+        (..succeeds? (/.check (.type (Ex [a] (Maybe a)))
+                              (.type (Ex [a] (Maybe a)))))
+
+        universals_satisfy_particulars!
+        (..succeeds? (/.check (.type (Maybe nominal))
+                              (.type (All [a] (Maybe a)))))
+
+        particulars_do_not_satisfy_universals!
+        (..fails? (/.check (.type (All [a] (Maybe a)))
+                           (.type (Maybe nominal))))
+
+        particulars_satisfy_existentials!
+        (..succeeds? (/.check (.type (Ex [a] (Maybe a)))
+                              (.type (Maybe nominal))))
+
+        existentials_do_not_satisfy_particulars!
+        (..fails? (/.check (.type (Maybe nominal))
+                           (.type (Ex [a] (Maybe a)))))]
+    (and universals_satisfy_themselves!
+         existentials_satisfy_themselves!
+
+         universals_satisfy_particulars!
+         particulars_do_not_satisfy_universals!
+         
+         particulars_satisfy_existentials!
+         existentials_do_not_satisfy_particulars!
+         )))
+
+(def: (handles_ultimates! nominal)
+  (-> Type Bit)
+  (let [any_is_the_ultimate_super_type!
+        (and (..succeeds? (/.check Any nominal))
+             (..fails? (/.check nominal Any)))
+
+        nothing_is_the_ultimate_sub_type!
+        (and (..succeeds? (/.check nominal Nothing))
+             (..fails? (/.check Nothing nominal)))
+
+        ultimates_check_themselves!
+        (and (..succeeds? (/.check Any Any))
+             (..succeeds? (/.check Nothing Nothing)))]
+    (and any_is_the_ultimate_super_type!
+         nothing_is_the_ultimate_sub_type!
+         ultimates_check_themselves!)))
+
+(def: (names_do_not_affect_types! left_name right_name nominal)
+  (-> Name Name Type Bit)
+  (and (..succeeds? (/.check (#.Named left_name Any) nominal))
+       (..succeeds? (/.check Any (#.Named right_name nominal)))
+       (..succeeds? (/.check (#.Named left_name Any) (#.Named right_name nominal)))))
+
+## TODO: Test all the crazy corner cases from /.check_apply
+(def: (handles_application! nominal/0 nominal/1)
+  (-> Type Type Bit)
+  (let [types_flow_through!
+        (and (..succeeds? (/.check (.type ((All [a] a) nominal/0))
+                                   nominal/0))
+             (..succeeds? (/.check nominal/0
+                                   (.type ((All [a] a) nominal/0))))
+
+             (..succeeds? (/.check (.type ((Ex [a] a) nominal/0))
+                                   nominal/0))
+             (..succeeds? (/.check nominal/0
+                                   (.type ((Ex [a] a) nominal/0)))))
+
+        multiple_parameters!
+        (and (..succeeds? (/.check (.type ((All [a b] [a b]) nominal/0 nominal/1))
+                                   (.type [nominal/0 nominal/1])))
+             (..succeeds? (/.check (.type [nominal/0 nominal/1])
+                                   (.type ((All [a b] [a b]) nominal/0 nominal/1))))
+             
+             (..succeeds? (/.check (.type ((Ex [a b] [a b]) nominal/0 nominal/1))
+                                   (.type [nominal/0 nominal/1])))
+             (..succeeds? (/.check (.type [nominal/0 nominal/1])
+                                   (.type ((Ex [a b] [a b]) nominal/0 nominal/1)))))]
+    (and types_flow_through!
+         multiple_parameters!)))
+
+(def: check
+  Test
+  (do {! random.monad}
+    [nominal ..nominal
+     [name/0 name/1] (..non_twins text\= (random.ascii/upper 10))
+     [parameter/0 parameter/1] (..non_twins type\= ..nominal)
+     left_name ..name
+     right_name ..name
+     ring_tail_size (\ ! map (n.% 10) random.nat)]
+    (_.cover [/.check]
+             (and (..handles_nominal_types! name/0 name/1 parameter/0 parameter/1)
+                  (..handles_products! name/0 name/1)
+                  (..handles_sums! name/0 name/1)
+                  (..handles_function_variance! nominal)
+                  (..handles_vars! nominal)
+                  (..handles_var_rings! ring_tail_size parameter/0 parameter/1)
+                  ..handles_existentials!
+                  (..handles_quantification! nominal)
+                  (..handles_ultimates! nominal)
+                  (..handles_application! parameter/0 parameter/1)
+                  (..names_do_not_affect_types! left_name right_name nominal)
+                  ))))
+
+(def: dirty_type
+  (Random (-> Type Type))
+  (random.rec
+   (function (_ dirty_type)
+     (`` ($_ random.either
+             (random\map (function (_ id)
+                           (function.constant (#.Ex id)))
+                         random.nat)
+             (do random.monad
+               [module (random.ascii/upper 10)
+                short (random.ascii/upper 10)
+                anonymousT dirty_type]
+               (wrap (function (_ holeT)
+                       (#.Named [module short] (anonymousT holeT)))))
+             (~~ (template [<tag>]
+                   [(do random.monad
+                      [leftT dirty_type
+                       rightT dirty_type]
+                      (wrap (function (_ holeT)
+                              (<tag> (leftT holeT) (rightT holeT)))))]
+
+                   [#.Sum]
+                   [#.Product]
+                   [#.Function]
+                   [#.Apply]
+                   ))
+             (do {! random.monad}
+               [name (random.ascii/upper 10)
+                parameterT dirty_type]
+               (wrap (function (_ holeT)
+                       (#.Primitive name (list (parameterT holeT))))))
+             (~~ (template [<tag>]
+                   [(do {! random.monad}
+                      [funcT dirty_type
+                       argT dirty_type
+                       body random.nat]
+                      (wrap (function (_ holeT)
+                              (<tag> (list (funcT holeT) (argT holeT))
+                                     (#.Parameter body)))))]
+
+                   [#.UnivQ]
+                   [#.ExQ]
+                   ))
+             )))))
+
+(def: clean
+  Test
+  (do random.monad
+    [type_shape ..dirty_type]
+    (_.cover [/.clean]
+             (and (|> (do /.monad
+                        [[var_id varT] /.var
+                         cleanedT (/.clean (type_shape varT))]
+                        (wrap (type\= (type_shape varT)
+                                      cleanedT)))
+                      (/.run /.fresh_context)
+                      (try.default false))
+                  (|> (do /.monad
+                        [[var_id varT] /.var
+                         [_ replacementT] /.existential
+                         _ (/.check varT replacementT)
+                         cleanedT (/.clean (type_shape varT))]
+                        (wrap (type\= (type_shape replacementT)
+                                      cleanedT)))
+                      (/.run /.fresh_context)
+                      (try.default false))
+                  ))))
+
+(def: #export test
+  Test
+  (<| (_.covering /._)
+      (_.for [/.Check])
+      ($_ _.and
+          ..polymorphism
           (do random.monad
-            [#let [gen_short (random.ascii 10)]
-             nameL gen_short
-             nameR (|> gen_short (random.filter (|>> (text\= nameL) not)))
-             paramL ..type
-             paramR (random.filter (|>> (/.checks? paramL) not) ..type)]
-            ($_ _.and
-                (_.test "Primitive types match when they have the same name and the same parameters."
-                        (/.checks? (#.Primitive nameL (list paramL))
-                                   (#.Primitive nameL (list paramL))))
-                (_.test "Names matter to primitive types."
-                        (not (/.checks? (#.Primitive nameL (list paramL))
-                                        (#.Primitive nameR (list paramL)))))
-                (_.test "Parameters matter to primitive types."
-                        (not (/.checks? (#.Primitive nameL (list paramL))
-                                        (#.Primitive nameL (list paramR)))))
-                ))
-          ($_ _.and
-              (_.test "Type-vars check against themselves."
-                      (type_checks? (do /.monad
-                                      [[id var] /.var]
-                                      (/.check var var))))
-              (_.test "Can bind unbound type-vars by type-checking against them."
-                      (and (type_checks? (do /.monad
-                                           [[id var] /.var]
-                                           (/.check var .Any)))
-                           (type_checks? (do /.monad
-                                           [[id var] /.var]
-                                           (/.check .Any var)))))
-              (_.test "Cannot rebind already bound type-vars."
-                      (not (type_checks? (do /.monad
-                                           [[id var] /.var
-                                            _ (/.check var .Bit)]
-                                           (/.check var .Nat)))))
-              (_.test "If the type bound to a var is a super-type to another, then the var is also a super-type."
-                      (type_checks? (do /.monad
-                                      [[id var] /.var
-                                       _ (/.check var Any)]
-                                      (/.check var .Bit))))
-              (_.test "If the type bound to a var is a sub-type of another, then the var is also a sub-type."
-                      (type_checks? (do /.monad
-                                      [[id var] /.var
-                                       _ (/.check var Nothing)]
-                                      (/.check .Bit var))))
-              )
-          (do {! random.monad}
-            [num_connections (|> random.nat (\ ! map (n.% 100)))
-             boundT (|> ..type (random.filter (|>> (case> (#.Var _) #0 _ #1))))
-             pick_pcg (random.and random.nat random.nat)]
-            ($_ _.and
-                (_.test "Can create rings of variables."
-                        (type_checks? (do /.monad
-                                        [[[head_id head_type] ids+types [tail_id tail_type]] (build_ring num_connections)
-                                         #let [ids (list\map product.left ids+types)]
-                                         headR (/.ring head_id)
-                                         tailR (/.ring tail_id)]
-                                        (/.assert ""
-                                                  (let [same_rings? (\ set.equivalence = headR tailR)
-                                                        expected_size? (n.= (inc num_connections) (set.size headR))
-                                                        same_vars? (|> (set.to_list headR)
-                                                                       (list.sort n.<)
-                                                                       (\ (list.equivalence n.equivalence) = (list.sort n.< (#.Cons head_id ids))))]
-                                                    (and same_rings?
-                                                         expected_size?
-                                                         same_vars?))))))
-                (_.test "When a var in a ring is bound, all the ring is bound."
-                        (type_checks? (do {! /.monad}
-                                        [[[head_id headT] ids+types tailT] (build_ring num_connections)
-                                         #let [ids (list\map product.left ids+types)]
-                                         _ (/.check headT boundT)
-                                         head_bound (/.read head_id)
-                                         tail_bound (monad.map ! /.read ids)
-                                         headR (/.ring head_id)
-                                         tailR+ (monad.map ! /.ring ids)]
-                                        (let [rings_were_erased? (and (set.empty? headR)
-                                                                      (list.every? set.empty? tailR+))
-                                              same_types? (list.every? (type\= boundT) (list& (maybe.default headT head_bound)
-                                                                                              (list\map (function (_ [tail_id ?tailT])
-                                                                                                          (maybe.default (#.Var tail_id) ?tailT))
-                                                                                                        (list.zip/2 ids tail_bound))))]
-                                          (/.assert ""
-                                                    (and rings_were_erased?
-                                                         same_types?))))))
-                (_.test "Can merge multiple rings of variables."
-                        (type_checks? (do /.monad
-                                        [[[head_idL headTL] ids+typesL [tail_idL tailTL]] (build_ring num_connections)
-                                         [[head_idR headTR] ids+typesR [tail_idR tailTR]] (build_ring num_connections)
-                                         headRL_pre (/.ring head_idL)
-                                         headRR_pre (/.ring head_idR)
-                                         _ (/.check headTL headTR)
-                                         headRL_post (/.ring head_idL)
-                                         headRR_post (/.ring head_idR)]
-                                        (/.assert ""
-                                                  (let [same_rings? (\ set.equivalence = headRL_post headRR_post)
-                                                        expected_size? (n.= (n.* 2 (inc num_connections))
-                                                                            (set.size headRL_post))
-                                                        union? (\ set.equivalence = headRL_post (set.union headRL_pre headRR_pre))]
-                                                    (and same_rings?
-                                                         expected_size?
-                                                         union?))))))
-                ))
+            [expected random.nat]
+            (_.cover [/.run]
+                     (case (/.run /.fresh_context
+                                  (\ /.monad wrap expected))
+                       (#try.Success actual) (is? expected actual)
+                       (#try.Failure error) false)))
+          ..error_handling
+          ..var
+          ..context
+          ..check
+          ..clean
           )))