Some small refactoring.

20 files changed, 253 insertions, 228 deletions

diff --git a/lux-jvm/source/program.lux b/lux-jvm/source/program.lux
index 61d97a9c7..433f76d36 100644
--- a/lux-jvm/source/program.lux
+++ b/lux-jvm/source/program.lux
@@ -114,7 +114,7 @@
   (do io.monad
     [## host jvm/host.host
      host jvm.host]
-    (wrap {#platform.&file-system (file.async file.system)
+    (wrap {#platform.&file-system (file.async file.default)
            #platform.host host
            ## #platform.phase jvm.generate
            #platform.phase expression.translate
@@ -172,6 +172,6 @@
                          ..extender
                          service
                          [packager.package
-                          (format (/cli.target service) (:: file.system separator) "program.jar")])]
+                          (format (/cli.target service) (:: file.default separator) "program.jar")])]
           (..declare-success! []))
     (io.io [])))
diff --git a/stdlib/source/lux/data/collection/sequence.lux b/stdlib/source/lux/data/collection/sequence.lux
index 5755e8214..2b046fee8 100644
--- a/stdlib/source/lux/data/collection/sequence.lux
+++ b/stdlib/source/lux/data/collection/sequence.lux
@@ -4,79 +4,72 @@
     [functor (#+ Functor)]
     [comonad (#+ CoMonad)]]
    [control
-    ["." continuation (#+ Cont pending)]
-    ["p" parser
-     ["s" code (#+ Parser)]]]
+    ["//" continuation (#+ Cont)]
+    ["<>" parser
+     ["<.>" code (#+ Parser)]]]
    [meta (#+ with-gensyms)]
    [macro
-    ["." code]
-    [syntax (#+ syntax:)]]
+    [syntax (#+ syntax:)]
+    ["." code]]
    [data
     ["." bit]
     [number
      ["n" nat]]
     [collection
-     ["." list ("#;." monad)]]]])
+     ["." list ("#@." monad)]]]])
 
 (type: #export (Sequence a)
   {#.doc "An infinite sequence of values."}
   (Cont [a (Sequence a)]))
 
-(def: (cycle' x xs init full)
-  (All [a]
-    (-> a (List a) a (List a) (Sequence a)))
-  (case xs
-    #.Nil
-    (pending [x (cycle' init full init full)])
-    
-    (#.Cons x' xs')
-    (pending [x (cycle' x' xs' init full)])))
-
 (def: #export (iterate f x)
   {#.doc "Create a sequence by applying a function to a value, and to its result, on and on..."}
   (All [a]
     (-> (-> a a) a (Sequence a)))
-  (pending [x (iterate f (f x))]))
+  (//.pending [x (iterate f (f x))]))
 
 (def: #export (repeat x)
   {#.doc "Repeat a value forever."}
   (All [a]
     (-> a (Sequence a)))
-  (pending [x (repeat x)]))
+  (//.pending [x (repeat x)]))
 
-(def: #export (cycle xs)
+(def: #export (cycle [start next])
   {#.doc (doc "Go over the elements of a list forever."
               "The list should not be empty.")}
   (All [a]
-    (-> (List a) (Maybe (Sequence a))))
-  (case xs
-    #.Nil
-    #.None
-    
-    (#.Cons x xs')
-    (#.Some (cycle' x xs' x xs'))))
-
-(template [<name> <return> <part>]
-  [(def: #export (<name> s)
+    (-> [a (List a)] (Sequence a)))
+  (loop [head start
+         tail next]
+    (//.pending [head (case tail
+                        #.Nil
+                        (recur start next)
+                        
+                        (#.Cons head' tail')
+                        (recur head' tail'))])))
+
+(template [<name> <return>]
+  [(def: #export (<name> sequence)
      (All [a] (-> (Sequence a) <return>))
-     (let [[h t] (continuation.run s)]
-       <part>))]
+     (let [[head tail] (//.run sequence)]
+       <name>))]
 
-  [head a          h]
-  [tail (Sequence a) t])
+  [head a]
+  [tail (Sequence a)]
+  )
 
-(def: #export (nth idx s)
+(def: #export (nth idx sequence)
   (All [a] (-> Nat (Sequence a) a))
-  (let [[h t] (continuation.run s)]
-    (if (n.> 0 idx)
-      (nth (dec idx) t)
-      h)))
+  (let [[head tail] (//.run sequence)]
+    (case idx
+      0 head
+      _ (nth (dec idx) tail))))
 
 (template [<taker> <dropper> <splitter> <pred-type> <pred-test> <pred-step>]
   [(def: #export (<taker> pred xs)
      (All [a]
        (-> <pred-type> (Sequence a) (List a)))
-     (let [[x xs'] (continuation.run xs)]
+     (let [[x xs'] (//.run xs)]
        (if <pred-test>
          (list& x (<taker> <pred-step> xs'))
          (list))))
@@ -84,7 +77,7 @@
    (def: #export (<dropper> pred xs)
      (All [a]
        (-> <pred-type> (Sequence a) (Sequence a)))
-     (let [[x xs'] (continuation.run xs)]
+     (let [[x xs'] (//.run xs)]
        (if <pred-test>
          (<dropper> <pred-step> xs')
          xs)))
@@ -92,13 +85,13 @@
    (def: #export (<splitter> pred xs)
      (All [a]
        (-> <pred-type> (Sequence a) [(List a) (Sequence a)]))
-     (let [[x xs'] (continuation.run xs)]
+     (let [[x xs'] (//.run xs)]
        (if <pred-test>
          (let [[tail next] (<splitter> <pred-step> xs')]
            [(#.Cons [x tail]) next])
          [(list) xs])))]
   
-  [take-while drop-while split-while (-> a Bit) (pred x)      pred]
+  [take-while drop-while split-while (-> a Bit) (pred x)     pred]
   [take       drop       split       Nat        (n.> 0 pred) (dec pred)]
   )
 
@@ -107,14 +100,14 @@
   (All [a b]
     (-> (-> a [a b]) a (Sequence b)))
   (let [[next x] (step init)]
-    (pending [x (unfold step next)])))
+    (//.pending [x (unfold step next)])))
 
-(def: #export (filter p xs)
+(def: #export (filter predicate sequence)
   (All [a] (-> (-> a Bit) (Sequence a) (Sequence a)))
-  (let [[x xs'] (continuation.run xs)]
-    (if (p x)
-      (pending [x (filter p xs')])
-      (filter p xs'))))
+  (let [[head tail] (//.run sequence)]
+    (if (predicate head)
+      (//.pending [head (filter predicate tail)])
+      (filter predicate tail))))
 
 (def: #export (partition left? xs)
   {#.doc (doc "Split a sequence in two based on a predicate."
@@ -123,29 +116,35 @@
   (All [a] (-> (-> a Bit) (Sequence a) [(Sequence a) (Sequence a)]))
   [(filter left? xs) (filter (bit.complement left?) xs)])
 
-(structure: #export functor (Functor Sequence)
+(structure: #export functor
+  (Functor Sequence)
+  
   (def: (map f fa)
-    (let [[h t] (continuation.run fa)]
-      (pending [(f h) (map f t)]))))
+    (let [[head tail] (//.run fa)]
+      (//.pending [(f head) (map f tail)]))))
 
-(structure: #export comonad (CoMonad Sequence)
+(structure: #export comonad
+  (CoMonad Sequence)
+  
   (def: &functor ..functor)
+  
   (def: unwrap head)
+  
   (def: (split wa)
-    (let [[head tail] (continuation.run wa)]
-      (pending [wa (split tail)]))))
+    (let [[head tail] (//.run wa)]
+      (//.pending [wa (split tail)]))))
 
-(syntax: #export (^sequence& {patterns (s.form (p.many s.any))}
+(syntax: #export (^sequence& {patterns (<code>.form (<>.many <code>.any))}
                              body
-                             {branches (p.some s.any)})
+                             {branches (<>.some <code>.any)})
   {#.doc (doc "Allows destructuring of sequences in pattern-matching expressions."
               "Caveat emptor: Only use it for destructuring, and not for testing values within the sequences."
               (let [(^sequence& x y z _tail) (some-sequence-func +1 +2 +3)]
                 (func x y z)))}
   (with-gensyms [g!sequence]
-    (let [body+ (` (let [(~+ (list;join (list;map (function (_ pattern)
+    (let [body+ (` (let [(~+ (list@join (list@map (function (_ pattern)
                                                     (list (` [(~ pattern) (~ g!sequence)])
-                                                          (` ((~! continuation.run) (~ g!sequence)))))
+                                                          (` ((~! //.run) (~ g!sequence)))))
                                                   patterns)))]
                      (~ body)))]
       (wrap (list& g!sequence body+ branches)))))
diff --git a/stdlib/source/lux/data/collection/set.lux b/stdlib/source/lux/data/collection/set.lux
index dfefcb1df..9321723c3 100644
--- a/stdlib/source/lux/data/collection/set.lux
+++ b/stdlib/source/lux/data/collection/set.lux
@@ -73,8 +73,7 @@
   (All [a] (-> (Hash a) (Monoid (Set a))))
 
   (def: identity (..new hash))
-  (def: compose ..union)
-  )
+  (def: compose ..union))
 
 (def: #export empty?
   (All [a] (-> (Set a) Bit))
@@ -90,7 +89,7 @@
 
 (def: #export (super? sub super)
   (All [a] (-> (Set a) (Set a) Bit))
-  (sub? super sub))
+  (..sub? super sub))
 
 (def: #export predicate
   (All [a] (-> (Set a) (Predicate a)))
diff --git a/stdlib/source/lux/data/format/json.lux b/stdlib/source/lux/data/format/json.lux
index 643d12969..2dbe32d91 100644
--- a/stdlib/source/lux/data/format/json.lux
+++ b/stdlib/source/lux/data/format/json.lux
@@ -47,8 +47,8 @@
 (template [<name> <type>]
   [(type: #export <name> <type>)]
 
-  [Array   (Row JSON)]
-  [Object  (Dictionary String JSON)]
+  [Array  (Row JSON)]
+  [Object (Dictionary String JSON)]
   )
 
 (def: #export object
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/jvm/debug.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/jvm/debug.lux
index 142c46224..657566813 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/jvm/debug.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/jvm/debug.lux
@@ -22,7 +22,7 @@
     (do io.monad
       [outcome (do (try.with @)
                  [file (: (IO (Try (File IO)))
-                          (file.get-file io.monad file.system file-path))]
+                          (file.get-file io.monad file.default file-path))]
                  (!.use (:: file over-write) bytecode))]
       (wrap (case outcome
               (#try.Success definition)
diff --git a/stdlib/source/lux/world/console.lux b/stdlib/source/lux/world/console.lux
index a66743b65..c1ad4e7e5 100644
--- a/stdlib/source/lux/world/console.lux
+++ b/stdlib/source/lux/world/console.lux
@@ -71,7 +71,7 @@
                                  (#static in java/io/InputStream)
                                  (#static out java/io/PrintStream))
 
-                               (def: #export system
+                               (def: #export default
                                  (IO (Try (Console IO)))
                                  (do io.monad
                                    [?jvm-console (java/lang/System::console)]
diff --git a/stdlib/source/lux/world/file.lux b/stdlib/source/lux/world/file.lux
index 5f1bbc6a8..277a3018d 100644
--- a/stdlib/source/lux/world/file.lux
+++ b/stdlib/source/lux/world/file.lux
@@ -390,7 +390,7 @@
                                             (function (discard _)
                                               (!delete path cannot-discard-directory))))))
 
-                                   (`` (structure: #export system
+                                   (`` (structure: #export default
                                          (System IO)
                                          
                                          (~~ (template [<name> <method> <capability> <exception>]
@@ -597,7 +597,7 @@
                         (function (discard _)
                           (Fs::rmdirSync [path] (..node-fs [])))))))
 
-               (`` (structure: #export system
+               (`` (structure: #export default
                      (System IO)
                      
                      (~~ (template [<name> <method> <capability> <exception>]
@@ -1126,3 +1126,22 @@
                (#try.Failure error)
                (wrap (#try.Failure error))))))))
      )))
+
+(def: #export (make-directories monad system path)
+  (All [!] (-> (Monad !) (System !) Path (! (Try Path))))
+  (case (text.split-all-with (:: system separator) path)
+    #.Nil
+    (:: monad wrap (exception.throw ..cannot-create-directory [path]))
+
+    (#.Cons head tail)
+    (loop [current head
+           next tail]
+      (do (try.with monad)
+        [_ (..get-directory monad system current)]
+        (case next
+          #.Nil
+          (wrap current)
+          
+          (#.Cons head tail)
+          (recur (format current (:: system separator) head)
+                 tail))))))
diff --git a/stdlib/source/program/aedifex.lux b/stdlib/source/program/aedifex.lux
index 76db24a47..485277d88 100644
--- a/stdlib/source/program/aedifex.lux
+++ b/stdlib/source/program/aedifex.lux
@@ -50,7 +50,7 @@
 (def: (install! profile)
   (-> /.Profile (Promise Any))
   (do promise.monad
-    [outcome (/local.install (file.async file.system) profile)]
+    [outcome (/local.install (file.async file.default) profile)]
     (wrap (case outcome
             (#try.Success _)
             (log! "Successfully installed locally!")
@@ -63,14 +63,14 @@
   (-> /.Profile (Promise Any))
   (do promise.monad
     [outcome (do (try.with promise.monad)
-               [cache (/local.all-cached (file.async file.system)
+               [cache (/local.all-cached (file.async file.default)
                                          (set.to-list (get@ #/.dependencies profile))
                                          /dependency.empty)
                 resolution (promise.future
                             (/dependency.resolve-all (set.to-list (get@ #/.repositories profile))
                                                      (set.to-list (get@ #/.dependencies profile))
                                                      cache))]
-               (/local.cache-all (file.async file.system)
+               (/local.cache-all (file.async file.default)
                                  resolution))]
     (wrap (case outcome
             (#try.Success _)
@@ -82,12 +82,12 @@
 
 (program: [{[profile operation] /cli.command}]
   (do {@ io.monad}
-    [?profile (/input.read io.monad file.system profile)]
+    [?profile (/input.read io.monad file.default profile)]
     (case ?profile
       (#try.Success profile)
       (case operation
         #/cli.POM
-        (exec (/command/pom.do! (file.async file.system) profile)
+        (exec (/command/pom.do! (file.async file.default) profile)
           (wrap []))
         
         #/cli.Dependencies
diff --git a/stdlib/source/program/aedifex/command/build.lux b/stdlib/source/program/aedifex/command/build.lux
index 6a1ab93d4..2d8ffb763 100644
--- a/stdlib/source/program/aedifex/command/build.lux
+++ b/stdlib/source/program/aedifex/command/build.lux
@@ -89,7 +89,7 @@
   (-> Resolution (List Path))
   (|>> dictionary.keys
        (list.filter (|>> (get@ #///dependency.type) (text@= ///artifact/type.lux-library)))
-       (list@map (|>> (get@ #///dependency.artifact) (///local.path file.system)))))
+       (list@map (|>> (get@ #///dependency.artifact) (///local.path file.default)))))
 
 (import: java/lang/String)
 
@@ -124,24 +124,24 @@
     
     [(#.Some program) (#.Some target)]
     (do ///action.monad
-      [cache (///local.all-cached (file.async file.system)
+      [cache (///local.all-cached (file.async file.default)
                                   (set.to-list (get@ #///.dependencies profile))
                                   ///dependency/resolution.empty)
        resolution (promise.future
                    (///dependency/resolution.resolve-all (set.to-list (get@ #///.repositories profile))
                                                          (set.to-list (get@ #///.dependencies profile))
                                                          cache))
-       _ (///local.cache-all (file.async file.system)
+       _ (///local.cache-all (file.async file.default)
                              resolution)
        [resolution compiler] (promise@wrap (..compiler resolution))
        working-directory (promise.future ..working-directory)
        #let [libraries (..libraries resolution)
              [prefix output] (case compiler
-                               (#JVM artifact) [(format "java -jar " (///local.path file.system artifact))
+                               (#JVM artifact) [(format "java -jar " (///local.path file.default artifact))
                                                 "program.jar"]
-                               (#JS artifact) [(format "node --stack_size=8192 " (///local.path file.system artifact))
+                               (#JS artifact) [(format "node --stack_size=8192 " (///local.path file.default artifact))
                                                "program.js"])
-             cache-directory (format working-directory (:: file.system separator) target)
+             cache-directory (format working-directory (:: file.default separator) target)
              command (format prefix " build"
                              " " (..plural-parameter "--library" libraries)
                              " " (..plural-parameter "--source" (set.to-list (get@ #///.sources profile)))
@@ -151,5 +151,5 @@
        outcome (///shell.execute command working-directory)
        #let [_ (log! "[BUILD ENDED]")]]
       (wrap [compiler
-             (format cache-directory (:: file.system separator) output)]))
+             (format cache-directory (:: file.default separator) output)]))
     ))
diff --git a/stdlib/source/program/aedifex/command/deploy.lux b/stdlib/source/program/aedifex/command/deploy.lux
index d7c7802b7..b8ac5c97c 100644
--- a/stdlib/source/program/aedifex/command/deploy.lux
+++ b/stdlib/source/program/aedifex/command/deploy.lux
@@ -65,7 +65,7 @@
                                    content))))]
       (do {@ ///action.monad}
         [library (:: @ map (binary.run tar.writer)
-                     (export.library (file.async file.system)
+                     (export.library (file.async file.default)
                                      (set.to-list (get@ #/.sources profile))))
          pom (promise@wrap (///pom.write profile))
          _ (deploy! ///artifact/type.pom (|> pom (:: xml.codec encode) encoding.to-utf8))
diff --git a/stdlib/source/program/aedifex/local.lux b/stdlib/source/program/aedifex/local.lux
index c7c72c827..674d99f04 100644
--- a/stdlib/source/program/aedifex/local.lux
+++ b/stdlib/source/program/aedifex/local.lux
@@ -26,7 +26,9 @@
      ["." tar]
      ["." xml]]]
    [world
-    ["." file (#+ Path File Directory)]]]
+    ["." file (#+ Path File Directory)]
+    [net
+     ["." uri]]]]
   [program
    [compositor
     ["." export]]]
@@ -40,31 +42,17 @@
    ["#." dependency (#+ Dependency)
     ["#/." resolution (#+ Package Resolution)]]])
 
-(def: (local system)
-  (All [a] (-> (file.System a) Path))
-  (format "~" (:: system separator) ".m2"))
-
 (def: (repository system)
   (All [a] (-> (file.System a) Path))
-  (format (..local system) (:: system separator) "repository"))
+  (let [/ (:: system separator)]
+    (format "~" / ".m2" / "repository")))
 
-(def: (guarantee-repository! system artifact)
-  (-> (file.System Promise) Artifact (Promise (Try Path)))
-  (do {@ (try.with promise.monad)}
-    [_ (: (Promise (Try (Directory Promise)))
-          (file.get-directory promise.monad system (..local system)))
-     #let [root (..repository system)]
-     _ (: (Promise (Try (Directory Promise)))
-          (file.get-directory promise.monad system root))]
-    (monad.fold @
-                (function (_ child parent)
-                  (do @
-                    [#let [path (format parent (:: system separator) child)]
-                     _ (: (Promise (Try (Directory Promise)))
-                          (file.get-directory promise.monad system path))]
-                    (wrap path)))
-                root
-                (//artifact.local artifact))))
+(def: #export (path system artifact)
+  (All [a] (-> (file.System a) Artifact Path))
+  (format (..repository system)
+          (:: system separator)
+          (text.replace-all uri.separator (:: system separator)
+                            (//artifact.path artifact))))
 
 (def: (save! system content file)
   (-> (file.System Promise) Binary Path (Promise (Try Any)))
@@ -78,7 +66,8 @@
   (case (get@ #/.identity profile)
     (#.Some identity)
     (do (try.with promise.monad)
-      [repository (..guarantee-repository! system identity)
+      [repository (: (Promise (Try Path))
+                     (file.make-directories promise.monad system (..path system identity)))
        #let [artifact-name (format repository (:: system separator) (//artifact.identity identity))]
        package (export.library system (set.to-list (get@ #/.sources profile)))
        _ (..save! system (binary.run tar.writer package)
@@ -93,7 +82,8 @@
 (def: #export (cache system [artifact type] package)
   (-> (file.System Promise) Dependency Package (Promise (Try Any)))
   (do (try.with promise.monad)
-    [directory (..guarantee-repository! system artifact)
+    [directory (: (Promise (Try Path))
+                  (file.make-directories promise.monad system (..path system artifact)))
      #let [prefix (format directory (:: system separator) (//artifact.identity artifact))]
      directory (: (Promise (Try (Directory Promise)))
                   (file.get-directory promise.monad system directory))
@@ -129,7 +119,8 @@
 (def: #export (cached system [artifact type])
   (-> (file.System Promise) Dependency (Promise (Try Package)))
   (do (try.with promise.monad)
-    [directory (..guarantee-repository! system artifact)
+    [directory (: (Promise (Try Path))
+                  (file.make-directories promise.monad system (..path system artifact)))
      #let [prefix (format directory (:: system separator) (//artifact.identity artifact))]
      pom (..read! system (format prefix //artifact/extension.pom))
      [pom dependencies] (:: promise.monad wrap
@@ -175,9 +166,3 @@
           
           (#try.Failure error)
           <next>)))))
-
-(def: #export (path system artifact)
-  (All [a] (-> (file.System a) Artifact Path))
-  (format (..repository system)
-          (:: system separator)
-          (//artifact.identity artifact)))
diff --git a/stdlib/source/program/compositor.lux b/stdlib/source/program/compositor.lux
index 1b17a4de8..3bc870f9b 100644
--- a/stdlib/source/program/compositor.lux
+++ b/stdlib/source/program/compositor.lux
@@ -142,7 +142,7 @@
                                         (:assume (platform.compile import static expander platform compilation [archive state]))})
                _ (ioW.freeze (get@ #platform.&file-system platform) static archive)
                program-context (promise@wrap ($/program.context archive))
-               _ (promise.future (..package! io.monad file.system packager,package static archive program-context))]
+               _ (promise.future (..package! io.monad file.default packager,package static archive program-context))]
               (wrap (log! "Compilation complete!"))))
 
         (#/cli.Export export)
@@ -157,7 +157,7 @@
         (undefined)
         ## (<| (or-crash! "Interpretation failed:")
         ##     (do {@ promise.monad}
-        ##       [console (|> console.system
+        ##       [console (|> console.default
         ##                    promise.future
         ##                    (:: @ map (|>> try.assume console.async)))]
         ##       (interpreter.run (try.with promise.monad) console platform interpretation generation-bundle)))
diff --git a/stdlib/source/program/licentia.lux b/stdlib/source/program/licentia.lux
index 7eab5b444..244e28223 100644
--- a/stdlib/source/program/licentia.lux
+++ b/stdlib/source/program/licentia.lux
@@ -57,7 +57,7 @@
   (do io.monad
     [?done (: (IO (Try Any))
               (do (try.with io.monad)
-                [file (!.use (:: file.system file) input)
+                [file (!.use (:: file.default file) input)
                  blob (!.use (:: file content) [])
                  document (io;wrap (do try.monad
                                      [raw-json (encoding.from-utf8 blob)
@@ -69,7 +69,7 @@
                                       license (json.run json /input.license)]
                                      (wrap (/output.license license))))
                  output-file (: (IO (Try (File IO)))
-                                (file.get-file io.monad file.system output))]
+                                (file.get-file io.monad file.default output))]
                 (!.use (:: output-file over-write) (encoding.to-utf8 document))))]
     (case ?done
       (#try.Success _)
diff --git a/stdlib/source/program/scriptum.lux b/stdlib/source/program/scriptum.lux
index bf12da1cd..1cb0ee21a 100644
--- a/stdlib/source/program/scriptum.lux
+++ b/stdlib/source/program/scriptum.lux
@@ -489,7 +489,7 @@
     (do io.monad
       [outcome (do (try.with io.monad)
                  [target (: (IO (Try (File IO)))
-                            (file.get-file io.monad file.system path))]
+                            (file.get-file io.monad file.default path))]
                  (!.use (:: target over-write) (encoding.to-utf8 (md.markdown documentation))))]
       (case outcome
         (#try.Failure error)
diff --git a/stdlib/source/spec/lux/abstract/comonad.lux b/stdlib/source/spec/lux/abstract/comonad.lux
index 3dfda0bbf..e434f6ab1 100644
--- a/stdlib/source/spec/lux/abstract/comonad.lux
+++ b/stdlib/source/spec/lux/abstract/comonad.lux
@@ -51,11 +51,11 @@
             (== (|> start _@split (_@map (|>> _@split (_@map increase) decrease)))
                 (|> start _@split (_@map increase) _@split (_@map decrease))))))
 
-(def: #export (spec injection comparison monad)
+(def: #export (spec injection comparison subject)
   (All [f] (-> (Injection f) (Comparison f) (CoMonad f) Test))
   (<| (_.with-cover [/.CoMonad])
       ($_ _.and
-          (..left-identity injection monad)
-          (..right-identity injection comparison monad)
-          (..associativity injection comparison monad)
+          (..left-identity injection subject)
+          (..right-identity injection comparison subject)
+          (..associativity injection comparison subject)
           )))
diff --git a/stdlib/source/test/aedifex/command/pom.lux b/stdlib/source/test/aedifex/command/pom.lux
index 1bb098de0..cd0eed8e9 100644
--- a/stdlib/source/test/aedifex/command/pom.lux
+++ b/stdlib/source/test/aedifex/command/pom.lux
@@ -33,7 +33,7 @@
   (<| (_.covering /._)
       (do random.monad
         [sample @profile.random
-         #let [fs (file.mock (:: file.system separator))]]
+         #let [fs (file.mock (:: file.default separator))]]
         (wrap (do {@ promise.monad}
                 [outcome (/.do! fs sample)]
                 (case outcome
diff --git a/stdlib/source/test/aedifex/input.lux b/stdlib/source/test/aedifex/input.lux
index 39a71eb81..50b99a218 100644
--- a/stdlib/source/test/aedifex/input.lux
+++ b/stdlib/source/test/aedifex/input.lux
@@ -34,7 +34,7 @@
       (do {@ random.monad}
         [expected (:: @ map (set@ #//.parents (list)) @profile.random)
          #let [fs (: (file.System Promise)
-                     (file.mock (:: file.system separator)))]]
+                     (file.mock (:: file.default separator)))]]
         (wrap (do promise.monad
                 [verdict (do //action.monad
                            [file (: (Promise (Try (File Promise)))
diff --git a/stdlib/source/test/lux/control/parser/binary.lux b/stdlib/source/test/lux/control/parser/binary.lux
index 11875d19f..98b8bab90 100644
--- a/stdlib/source/test/lux/control/parser/binary.lux
+++ b/stdlib/source/test/lux/control/parser/binary.lux
@@ -100,7 +100,7 @@
                   random.nat
                   random.int
                   random.rev
-                  random.frac
+                  random.safe-frac
                   ..random-text
                   ..random-name
                   ..random-name
@@ -213,8 +213,17 @@
                 [/.bit format.bit random.bit bit.equivalence]
                 [/.nat format.nat random.nat n.equivalence]
                 [/.int format.int random.int int.equivalence]
-                [/.rev format.rev random.rev rev.equivalence]
-                [/.frac format.frac random.frac frac.equivalence]))
+                [/.rev format.rev random.rev rev.equivalence]))
+          (do {@ random.monad}
+            [expected random.frac]
+            (_.cover [/.frac]
+                     (|> expected
+                         (format.run format.frac)
+                         (/.run /.frac)
+                         (!expect (^multi (#try.Success actual)
+                                          (or (:: frac.equivalence = expected actual)
+                                              (and (frac.not-a-number? expected)
+                                                   (frac.not-a-number? actual))))))))
           (do {@ random.monad}
             [expected (:: @ map (|>> (i64.and (i64.mask /.size/8))
                                      (n.max 2))
diff --git a/stdlib/source/test/lux/data/collection/sequence.lux b/stdlib/source/test/lux/data/collection/sequence.lux
index f47629d70..3cd41c4b2 100644
--- a/stdlib/source/test/lux/data/collection/sequence.lux
+++ b/stdlib/source/test/lux/data/collection/sequence.lux
@@ -1,102 +1,116 @@
 (.module:
   [lux #*
-   ["%" data/text/format (#+ format)]
    ["_" test (#+ Test)]
    [abstract
-    comonad
+    [comonad (#+)]
     [functor (#+)]
     [monad (#+ do)]
-    ["." enum]]
+    [equivalence (#+ Equivalence)]
+    ["." enum]
+    {[0 #spec]
+     [/
+      ["$." functor]
+      ["$." comonad]]}]
    [data
-    ["." maybe]
     [number
-     ["n" nat ("#@." decimal)]]
-    ["." text ("#@." monoid)]
+     ["n" nat]]
+    ["." text
+     ["%" format (#+ format)]]
     [collection
-     ["." list]]]
+     ["." list ("#@." functor)]]]
    [math
-    ["r" random]]]
+    ["." random]]]
   {1
    ["." /]})
 
+(structure: (equivalence super)
+  (All [a] (-> (Equivalence a) (Equivalence (/.Sequence a))))
+
+  (def: (= reference subject)
+    (:: (list.equivalence super) =
+        (/.take 100 reference)
+        (/.take 100 subject))))
+
 (def: #export test
   Test
-  (<| (_.context (%.name (name-of /.Sequence)))
-      (do {@ r.monad}
-        [size (|> r.nat (:: @ map (|>> (n.% 100) (n.max 2))))
-         offset (|> r.nat (:: @ map (n.% 100)))
-         factor (|> r.nat (:: @ map (|>> (n.% 100) (n.max 2))))
-         elem r.nat
-         cycle-seed (r.list size r.nat)
-         cycle-sample-idx (|> r.nat (:: @ map (n.% 1000)))
-         #let [(^open "list@.") (list.equivalence n.equivalence)
-               sample0 (/.iterate inc 0)
-               sample1 (/.iterate inc offset)]]
+  (<| (_.covering /._)
+      (_.with-cover [/.Sequence])
+      (let [(^open "list@.") (list.equivalence n.equivalence)])
+      (do {@ random.monad}
+        [repeated random.nat
+         index (:: @ map (n.% 100) random.nat)
+         size (:: @ map (|>> (n.% 10) inc) random.nat)
+         offset (:: @ map (n.% 100) random.nat)
+         cycle-start random.nat
+         cycle-next (random.list size random.nat)]
         ($_ _.and
-            (_.test "Can move along a sequence and take slices off it."
-                    (and (and (list@= (enum.range n.enum 0 (dec size))
-                                      (/.take size sample0))
-                              (list@= (enum.range n.enum offset (dec (n.+ offset size)))
-                                      (/.take size (/.drop offset sample0)))
-                              (let [[drops takes] (/.split size sample0)]
-                                (and (list@= (enum.range n.enum 0 (dec size))
-                                             drops)
-                                     (list@= (enum.range n.enum size (dec (n.* 2 size)))
-                                             (/.take size takes)))))
-                         (and (list@= (enum.range n.enum 0 (dec size))
-                                      (/.take-while (n.< size) sample0))
-                              (list@= (enum.range n.enum offset (dec (n.+ offset size)))
-                                      (/.take-while (n.< (n.+ offset size))
-                                                    (/.drop-while (n.< offset) sample0)))
-                              (let [[drops takes] (/.split-while (n.< size) sample0)]
-                                (and (list@= (enum.range n.enum 0 (dec size))
-                                             drops)
-                                     (list@= (enum.range n.enum size (dec (n.* 2 size)))
-                                             (/.take-while (n.< (n.* 2 size)) takes)))))
-                         ))
-            (_.test "Can repeat any element and infinite number of times."
-                    (n.= elem (/.nth offset (/.repeat elem))))
-            (_.test "Can obtain the head & tail of a sequence."
-                    (and (n.= offset (/.head sample1))
-                         (list@= (enum.range n.enum (inc offset) (n.+ offset size))
-                                 (/.take size (/.tail sample1)))))
-            (_.test "Can filter sequences."
-                    (and (n.= (n.* 2 offset)
-                              (/.nth offset
-                                     (/.filter n.even? sample0)))
-                         (let [[evens odds] (/.partition n.even? (/.iterate inc 0))]
-                           (and (n.= (n.* 2 offset)
-                                     (/.nth offset evens))
-                                (n.= (inc (n.* 2 offset))
-                                     (/.nth offset odds))))))
-            (_.test "Functor goes over 'all' elements in a sequence."
-                    (let [(^open "/@.") /.functor
-                          there (/@map (n.* factor) sample0)
-                          back-again (/@map (n./ factor) there)]
-                      (and (not (list@= (/.take size sample0)
-                                        (/.take size there)))
-                           (list@= (/.take size sample0)
-                                   (/.take size back-again)))))
-            (_.test "CoMonad produces a value for every element in a sequence."
-                    (let [(^open "/@.") /.functor]
-                      (list@= (/.take size (/@map (n.* factor) sample1))
-                              (/.take size
-                                      (be /.comonad
-                                        [inputs sample1]
-                                        (n.* factor (/.head inputs)))))))
-            (_.test "'unfold' generalizes 'iterate'."
-                    (let [(^open "/@.") /.functor
-                          (^open "list@.") (list.equivalence text.equivalence)]
-                      (list@= (/.take size
-                                      (/@map n@encode (/.iterate inc offset)))
-                              (/.take size
-                                      (/.unfold (function (_ n) [(inc n) (n@encode n)])
-                                                offset)))))
-            (_.test "Can cycle over the same elements as an infinite sequence."
-                    (|> (/.cycle cycle-seed)
-                        maybe.assume
-                        (/.nth cycle-sample-idx)
-                        (n.= (|> cycle-seed
-                                 (list.nth (n.% size cycle-sample-idx))
-                                 maybe.assume))))
+            (_.with-cover [/.functor]
+              ($functor.spec /.repeat ..equivalence /.functor))
+            (_.with-cover [/.comonad]
+              ($comonad.spec /.repeat ..equivalence /.comonad))
+            
+            (_.cover [/.iterate /.nth]
+                     (n.= (n.+ offset index)
+                          (/.nth index (/.iterate inc offset))))
+            (_.cover [/.repeat]
+                     (n.= repeated
+                          (/.nth index (/.repeat repeated))))
+            (_.cover [/.take]
+                     (list@= (enum.range n.enum offset (dec (n.+ size offset)))
+                             (/.take size (/.iterate inc offset))))
+            (_.cover [/.drop]
+                     (list@= (enum.range n.enum offset (dec (n.+ size offset)))
+                             (/.take size (/.drop offset (/.iterate inc 0)))))
+            (_.cover [/.split]
+                     (let [[drops takes] (/.split size (/.iterate inc 0))]
+                       (and (list@= (enum.range n.enum 0 (dec size))
+                                    drops)
+                            (list@= (enum.range n.enum size (dec (n.* 2 size)))
+                                    (/.take size takes)))))
+            (_.cover [/.take-while]
+                     (list@= (enum.range n.enum 0 (dec size))
+                             (/.take-while (n.< size) (/.iterate inc 0))))
+            (_.cover [/.drop-while]
+                     (list@= (enum.range n.enum offset (dec (n.+ size offset)))
+                             (/.take-while (n.< (n.+ size offset))
+                                           (/.drop-while (n.< offset) (/.iterate inc 0)))))
+            (_.cover [/.split-while]
+                     (let [[drops takes] (/.split-while (n.< size) (/.iterate inc 0))]
+                       (and (list@= (enum.range n.enum 0 (dec size))
+                                    drops)
+                            (list@= (enum.range n.enum size (dec (n.* 2 size)))
+                                    (/.take-while (n.< (n.* 2 size)) takes)))))
+            (_.cover [/.head]
+                     (n.= offset
+                          (/.head (/.iterate inc offset))))
+            (_.cover [/.tail]
+                     (list@= (enum.range n.enum (inc offset) (n.+ size offset))
+                             (/.take size (/.tail (/.iterate inc offset)))))
+            (_.cover [/.filter]
+                     (list@= (list@map (n.* 2) (enum.range n.enum 0 (dec size)))
+                             (/.take size (/.filter n.even? (/.iterate inc 0)))))
+            (_.cover [/.partition]
+                     (let [[evens odds] (/.partition n.even? (/.iterate inc 0))]
+                       (and (n.= (n.* 2 offset)
+                                 (/.nth offset evens))
+                            (n.= (inc (n.* 2 offset))
+                                 (/.nth offset odds)))))
+            (_.cover [/.unfold]
+                     (let [(^open "/@.") /.functor
+                           (^open "list@.") (list.equivalence text.equivalence)]
+                       (list@= (/.take size
+                                       (/@map %.nat (/.iterate inc offset)))
+                               (/.take size
+                                       (/.unfold (function (_ n) [(inc n) (%.nat n)])
+                                                 offset)))))
+            (_.cover [/.cycle]
+                     (let [cycle (list& cycle-start cycle-next)]
+                       (list@= (list.concat (list.repeat size cycle))
+                               (/.take (n.* size (list.size cycle))
+                                       (/.cycle [cycle-start cycle-next])))))
+            (_.cover [/.^sequence&]
+                     (let [(/.^sequence& first second third next) (/.iterate inc offset)]
+                       (and (n.= offset first)
+                            (n.= (n.+ 1 offset) second)
+                            (n.= (n.+ 2 offset) third))))
             ))))
diff --git a/stdlib/source/test/lux/world/file.lux b/stdlib/source/test/lux/world/file.lux
index 9dc1fb2e2..a1146fe56 100644
--- a/stdlib/source/test/lux/world/file.lux
+++ b/stdlib/source/test/lux/world/file.lux
@@ -39,9 +39,9 @@
              result (promise.future
                      (do (try.with io.monad)
                        [#let [check-existence! (: (IO (Try Bit))
-                                                  (try.lift io.monad (/.exists? io.monad /.system path)))]
+                                                  (try.lift io.monad (/.exists? io.monad /.default path)))]
                         pre! check-existence!
-                        file (!.use (:: /.system create-file) path)
+                        file (!.use (:: /.default create-file) path)
                         post! check-existence!
                         _ (!.use (:: file delete) [])
                         remains? check-existence!]
@@ -57,7 +57,7 @@
             [#let [path (format "temp_file_" (%.nat number))]
              result (promise.future
                      (do (try.with io.monad)
-                       [file (!.use (:: /.system create-file) path)
+                       [file (!.use (:: /.default create-file) path)
                         _ (!.use (:: file over-write) data)
                         content (!.use (:: file content) [])
                         _ (!.use (:: file delete) [])]
@@ -84,7 +84,7 @@
                     [#let [path "temp_file_2"]
                      result (promise.future
                              (do (try.with io.monad)
-                               [file (!.use (:: /.system create-file) path)
+                               [file (!.use (:: /.default create-file) path)
                                 _ (!.use (:: file over-write) dataL)
                                 read-size (!.use (:: file size) [])
                                 _ (!.use (:: file delete) [])]
@@ -95,7 +95,7 @@
                     [#let [path "temp_file_3"]
                      result (promise.future
                              (do (try.with io.monad)
-                               [file (!.use (:: /.system create-file) path)
+                               [file (!.use (:: /.default create-file) path)
                                 _ (!.use (:: file over-write) dataL)
                                 _ (!.use (:: file append) dataR)
                                 content (!.use (:: file content) [])
@@ -115,9 +115,9 @@
                      result (promise.future
                              (do (try.with io.monad)
                                [#let [check-existence! (: (IO (Try Bit))
-                                                          (try.lift io.monad (/.exists? io.monad /.system path)))]
+                                                          (try.lift io.monad (/.exists? io.monad /.default path)))]
                                 pre! check-existence!
-                                dir (!.use (:: /.system create-directory) path)
+                                dir (!.use (:: /.default create-directory) path)
                                 post! check-existence!
                                 _ (!.use (:: dir discard) [])
                                 remains? check-existence!]
@@ -131,8 +131,8 @@
                            dir-path "temp_dir_5"]
                      result (promise.future
                              (do (try.with io.monad)
-                               [dir (!.use (:: /.system create-directory) dir-path)
-                                file (!.use (:: /.system create-file) (format dir-path "/" file-path))
+                               [dir (!.use (:: /.default create-directory) dir-path)
+                                file (!.use (:: /.default create-file) (format dir-path "/" file-path))
                                 _ (!.use (:: file over-write) dataL)
                                 read-size (!.use (:: file size) [])
                                 _ (!.use (:: file delete) [])
@@ -146,12 +146,12 @@
                            inner-dir-path "inner_temp_dir_6"]
                      result (promise.future
                              (do (try.with io.monad)
-                               [dir (!.use (:: /.system create-directory) dir-path)
+                               [dir (!.use (:: /.default create-directory) dir-path)
                                 pre-files (!.use (:: dir files) [])
                                 pre-directories (!.use (:: dir directories) [])
                                 
-                                file (!.use (:: /.system create-file) (format dir-path "/" file-path))
-                                inner-dir (!.use (:: /.system create-directory) (format dir-path "/" inner-dir-path))
+                                file (!.use (:: /.default create-file) (format dir-path "/" file-path))
+                                inner-dir (!.use (:: /.default create-directory) (format dir-path "/" inner-dir-path))
                                 post-files (!.use (:: dir files) [])
                                 post-directories (!.use (:: dir directories) [])
                                 
@@ -168,7 +168,7 @@
                     [#let [path "temp_file_7"]
                      result (promise.future
                              (do (try.with io.monad)
-                               [file (!.use (:: /.system create-file) path)
+                               [file (!.use (:: /.default create-file) path)
                                 _ (!.use (:: file over-write) dataL)
                                 _ (!.use (:: file modify) new-modified)
                                 current-modified (!.use (:: file last-modified) [])
@@ -182,9 +182,9 @@
                      result (promise.future
                              (do (try.with io.monad)
                                [#let [check-existence! (: (-> Path (IO (Try Bit)))
-                                                          (|>> (/.exists? io.monad /.system)
+                                                          (|>> (/.exists? io.monad /.default)
                                                                (try.lift io.monad)))]
-                                file0 (!.use (:: /.system create-file) path0)
+                                file0 (!.use (:: /.default create-file) path0)
                                 _ (!.use (:: file0 over-write) dataL)
                                 pre! (check-existence! path0)
                                 file1 (: (IO (Try (File IO))) ## TODO: Remove :