Removed the (ultimately redundant) on_stop function for actors.

27 files changed, 724 insertions, 334 deletions

diff --git a/compilers.md b/compilers.md
index 0b629ee08..f454889b4 100644
--- a/compilers.md
+++ b/compilers.md
@@ -94,7 +94,8 @@ cd ~/lux/lux-js/ \
 cd ~/lux/lux-js/ \
 && lein clean \
 && cd ~/lux/lux-js/ \
-&& time node --stack_size=8192 program.js build --source ~/lux/lux-js/source --target ~/lux/lux-js/target --module program
+&& time node --stack_size=8192 _program.js build --source ~/lux/lux-js/source --target ~/lux/lux-js/target --module program \
+&& mv target/program.js program.js
 ```
 
 ## Try
@@ -103,7 +104,11 @@ cd ~/lux/lux-js/ \
 cd ~/lux/stdlib/ && lein clean && cd ~/lux/lux-js/ && time java -jar program.jar build --source ~/lux/stdlib/source --target ~/lux/stdlib/target --module test/lux
 cd ~/lux/stdlib/target/ && node program.js
 
-cd ~/lux/stdlib/ && lein clean && cd ~/lux/lux-js/ && time node --stack_size=8192 program.js build --source ~/lux/stdlib/source --target ~/lux/stdlib/target --module test/lux
+## Compile Lux's Standard Library's tests using a JS/Node-based compiler.
+cd ~/lux/stdlib/ \
+&& lein clean \
+&& cd ~/lux/lux-js/ \
+&& time node --stack_size=8192 program.js build --source ~/lux/stdlib/source --target ~/lux/stdlib/target --module test/lux
 ```
 
 ---
diff --git a/lux-python/source/program.lux b/lux-python/source/program.lux
index bdf2883ab..d42671d75 100644
--- a/lux-python/source/program.lux
+++ b/lux-python/source/program.lux
@@ -32,6 +32,8 @@
    [tool
     [compiler
      [phase (#+ Operation Phase)]
+     [reference
+      [variable (#+ Register)]]
      [language
       [lux
        [program (#+ Program)]
@@ -93,7 +95,7 @@
 
 (import: org/python/core/PyFunction
   ["#::."
-   (__call__ [[org/python/core/PyObject]] org/python/core/PyObject)])
+   (__call__ [[org/python/core/PyObject]] #try org/python/core/PyObject)])
 
 (import: org/python/core/PyArray
   ["#::."
@@ -214,10 +216,10 @@
   (-> (List Code) Lux org/python/core/PyFunction (Try (Try [Lux (List Code)])))
   (:assume
    (do try.monad
-     [expansion (host.try (org/python/core/PyFunction::__call__ (|> (host.array org/python/core/PyObject 2)
-                                                                    (host.array_write 0 (..to_host inputs))
-                                                                    (host.array_write 1 (..to_host lux)))
-                                                                macro))]
+     [expansion (org/python/core/PyFunction::__call__ (|> (host.array org/python/core/PyObject 2)
+                                                          (host.array_write 0 (..to_host inputs))
+                                                          (host.array_write 1 (..to_host lux)))
+                                                      macro)]
      (..read expansion))))
 
 (def: (expander macro inputs lux)
@@ -235,8 +237,7 @@
       (#try.Failure error))
 
     #.None
-    (exception.throw ..cannot_apply_a_non_function (:coerce java/lang/Object macro)))
-  )
+    (exception.throw ..cannot_apply_a_non_function (:coerce java/lang/Object macro))))
 
 (def: host
   (IO (Host (_.Expression Any) (_.Statement Any)))
@@ -248,9 +249,7 @@
                              (..read output))))
             execute! (: (-> (_.Statement Any) (Try Any))
                         (function (execute! input)
-                          (do try.monad
-                            [_ (org/python/util/PythonInterpreter::exec (_.code input) interpreter)]
-                            (wrap []))))]
+                          (org/python/util/PythonInterpreter::exec (_.code input) interpreter)))]
         (: (Host (_.Expression Any) (_.Statement Any))
            (structure
             (def: evaluate! evaluate!)
@@ -276,7 +275,7 @@
                 (evaluate! context (_.var (reference.artifact context))))))))))
 
 (def: platform
-  (IO (Platform _.SVar (_.Expression Any) (_.Statement Any)))
+  (IO (Platform [Register _.SVar] (_.Expression Any) (_.Statement Any)))
   (do io.monad
     [host ..host]
     (wrap {#platform.&file_system (file.async file.default)
@@ -311,14 +310,13 @@
             (:coerce Try)
             (do try.monad
               [handler (try.from_maybe (..ensure_function handler))
-               output (host.try
-                       (org/python/core/PyFunction::__call__ (|> (host.array org/python/core/PyObject 5)
-                                                                 (host.array_write 0 (org/python/core/PyString::new name))
-                                                                 (host.array_write 1 (..to_host phase))
-                                                                 (host.array_write 2 (..to_host archive))
-                                                                 (host.array_write 3 (..to_host parameters))
-                                                                 (host.array_write 4 (..to_host state)))
-                                                             handler))]
+               output (org/python/core/PyFunction::__call__ (|> (host.array org/python/core/PyObject 5)
+                                                                (host.array_write 0 (org/python/core/PyString::new name))
+                                                                (host.array_write 1 (..to_host phase))
+                                                                (host.array_write 2 (..to_host archive))
+                                                                (host.array_write 3 (..to_host parameters))
+                                                                (host.array_write 4 (..to_host state)))
+                                                            handler)]
               (..read output))))
 
       @.python
@@ -351,7 +349,7 @@
                            generation.bundle
                            extension/bundle.empty
                            ..program
-                           [_.SVar (type (_.Expression Any)) (type (_.Statement Any))]
+                           [(& Register _.SVar) (type (_.Expression Any)) (type (_.Statement Any))]
                            ..extender
                            service
                            [(packager.package (<| (_.comment "-*- coding: utf-8 -*-")
diff --git a/stdlib/source/lux/control/concurrency/actor.lux b/stdlib/source/lux/control/concurrency/actor.lux
index 3828b6d83..584bf614e 100644
--- a/stdlib/source/lux/control/concurrency/actor.lux
+++ b/stdlib/source/lux/control/concurrency/actor.lux
@@ -74,13 +74,12 @@
     (type: #export (Behavior o s)
       {#.doc "An actor's behavior when mail is received and when a fatal error occurs."}
       {#on_init (-> o s)
-       #on_mail (-> (Mail s) s (Actor s) (Promise (Try s)))
-       #on_stop (-> Text s (Promise Any))})
+       #on_mail (-> (Mail s) s (Actor s) (Promise (Try s)))})
 
     (def: #export (spawn! behavior init)
       {#.doc "Given a behavior and initial state, spawns an actor and returns it."}
       (All [o s] (-> (Behavior o s) o (IO (Actor s))))
-      (io (let [[on_init on_mail on_stop] behavior
+      (io (let [[on_init on_mail] behavior
                 self (:share [o s]
                              {(Behavior o s)
                               behavior}
@@ -94,14 +93,12 @@
                              ?state' (on_mail head state self)]
                             (case ?state'
                               (#try.Failure error)
-                              (do !
-                                [_ (on_stop error state)]
-                                (let [[_ resolve] (get@ #obituary (:representation self))]
-                                  (exec (io.run
-                                         (do io.monad
-                                           [pending (..pending tail)]
-                                           (resolve [error state (#.Cons head pending)])))
-                                    (wrap []))))
+                              (let [[_ resolve] (get@ #obituary (:representation self))]
+                                (exec (io.run
+                                       (do io.monad
+                                         [pending (..pending tail)]
+                                         (resolve [error state (#.Cons head pending)])))
+                                  (wrap [])))
 
                               (#try.Success state')
                               (recur state' tail))))]
@@ -199,15 +196,10 @@
   (All [s] (-> (Mail s) s (Actor s) (Promise (Try s))))
   (mail state self))
 
-(def: (default_on_stop cause state)
-  (All [s] (-> Text s (Promise Any)))
-  (promise\wrap []))
-
 (def: #export default
   (All [s] (Behavior s s))
   {#on_init function.identity
-   #on_mail ..default_on_mail
-   #on_stop ..default_on_stop})
+   #on_mail ..default_on_mail})
 
 (def: #export (poison! actor)
   {#.doc (doc "Kills the actor by sending mail that will kill it upon processing,"
@@ -225,11 +217,8 @@
 (type: On_MailC
   [[Text Text Text] Code])
 
-(type: On_StopC
-  [[Text Text] Code])
-
 (type: BehaviorC
-  [(Maybe On_MailC) (Maybe On_StopC) (List Code)])
+  [(Maybe On_MailC) (List Code)])
 
 (def: argument
   (Parser Text)
@@ -237,13 +226,10 @@
 
 (def: behavior^
   (Parser BehaviorC)
-  (let [on_mail_args ($_ <>.and ..argument ..argument ..argument)
-        on_stop_args ($_ <>.and ..argument ..argument)]
+  (let [on_mail_args ($_ <>.and ..argument ..argument ..argument)]
     ($_ <>.and
         (<>.maybe (<c>.form (<>.and (<c>.form (<>.after (<c>.this! (' on_mail)) on_mail_args))
                                     <c>.any)))
-        (<>.maybe (<c>.form (<>.and (<c>.form (<>.after (<c>.this! (' on_stop)) on_stop_args))
-                                    <c>.any)))
         (<>.some <c>.any))))
 
 (def: (on_mail g!_ ?on_mail)
@@ -259,18 +245,6 @@
                   (~ (code.local_identifier selfN)))
          (~ bodyC)))))
 
-(def: (on_stop g!_ ?on_stop)
-  (-> Code (Maybe On_StopC) Code)
-  (case ?on_stop
-    #.None
-    (` (~! ..default_on_stop))
-
-    (#.Some [[causeN stateN] bodyC])
-    (` (function ((~ g!_)
-                  (~ (code.local_identifier causeN))
-                  (~ (code.local_identifier stateN)))
-         (~ bodyC)))))
-
 (with_expansions [<examples> (as_is (actor: #export (Stack a)
                                       (List a)
 
@@ -288,12 +262,6 @@
                                     (actor: #export Counter
                                       Nat
 
-                                      ((on_stop cause state)
-                                       (\ promise.monad wrap
-                                          (log! (if (exception.match? ..poisoned cause)
-                                                  (format "Counter was poisoned: " (%.nat state))
-                                                  cause))))
-
                                       (message: #export (count! {increment Nat} state self Any)
                                         (let [state' (n.+ increment state)]
                                           (promise.resolved (#try.Success [state' state']))))
@@ -305,9 +273,9 @@
                      {[name vars] actor_decl^}
                      {annotations (<>.default |annotations|.empty |annotations|.parser)}
                      state_type
-                     {[?on_mail ?on_stop messages] behavior^})
+                     {[?on_mail messages] behavior^})
     {#.doc (doc "Defines an actor, with its behavior and internal state."
-                "Messages for the actor must be defined after the on_mail and on_stop handlers."
+                "Messages for the actor must be defined after the on_mail handler."
                 <examples>)}
     (with_gensyms [g!_]
       (do meta.monad
@@ -321,19 +289,17 @@
                           (All [(~+ g!vars)]
                             (..Behavior (~ state_type) ((~ g!type) (~+ g!vars))))
                           {#..on_init (|>> ((~! abstract.:abstraction) (~ g!type)))
-                           #..on_mail (~ (..on_mail g!_ ?on_mail))
-                           #..on_stop (~ (..on_stop g!_ ?on_stop))})
+                           #..on_mail (~ (..on_mail g!_ ?on_mail))})
 
                         (~+ messages))))))))
 
   (syntax: #export (actor {[state_type init] (<c>.record (<>.and <c>.any <c>.any))}
-                          {[?on_mail ?on_stop messages] behavior^})
+                          {[?on_mail messages] behavior^})
     (with_gensyms [g!_]
       (wrap (list (` (: ((~! io.IO) (..Actor (~ state_type)))
                         (..spawn! (: (..Behavior (~ state_type) (~ state_type))
                                      {#..on_init (|>>)
-                                      #..on_mail (~ (..on_mail g!_ ?on_mail))
-                                      #..on_stop (~ (..on_stop g!_ ?on_stop))})
+                                      #..on_mail (~ (..on_mail g!_ ?on_mail))})
                                   (: (~ state_type)
                                      (~ init)))))))))
 
diff --git a/stdlib/source/lux/control/parser/xml.lux b/stdlib/source/lux/control/parser/xml.lux
index 3b9732ae5..a9d9144b8 100644
--- a/stdlib/source/lux/control/parser/xml.lux
+++ b/stdlib/source/lux/control/parser/xml.lux
@@ -38,8 +38,8 @@
 
 (def: #export text
   (Parser Text)
-  (function (_ docs)
-    (case docs
+  (function (_ documents)
+    (case documents
       #.Nil
       (exception.throw ..empty_input [])
       
@@ -53,8 +53,8 @@
 
 (def: #export (node expected)
   (-> Tag (Parser Any))
-  (function (_ docs)
-    (case docs
+  (function (_ documents)
+    (case documents
       #.Nil
       (exception.throw ..empty_input [])
       
@@ -65,13 +65,13 @@
         
         (#/.Node actual _attributes _children)
         (if (name\= expected actual)
-          (#try.Success [docs []])
+          (#try.Success [documents []])
           (exception.throw ..wrong_tag [expected actual]))))))
 
 (def: #export tag
   (Parser Tag)
-  (function (_ docs)
-    (case docs
+  (function (_ documents)
+    (case documents
       #.Nil
       (exception.throw ..empty_input [])
       
@@ -81,12 +81,12 @@
         (exception.throw ..unexpected_input [])
         
         (#/.Node tag _attributes _children)
-        (#try.Success [docs tag])))))
+        (#try.Success [documents tag])))))
 
 (def: #export (attribute name)
   (-> Attribute (Parser Text))
-  (function (_ docs)
-    (case docs
+  (function (_ documents)
+    (case documents
       #.Nil
       (exception.throw ..empty_input [])
       
@@ -101,11 +101,11 @@
           (exception.throw ..unknown_attribute [name (dictionary.keys attributes)])
           
           (#.Some value)
-          (#try.Success [docs value]))))))
+          (#try.Success [documents value]))))))
 
-(def: (run' parser docs)
+(def: #export (run parser documents)
   (All [a] (-> (Parser a) (List XML) (Try a)))
-  (case (//.run parser docs)
+  (case (//.run parser documents)
     (#try.Success [remaining output])
     (if (list.empty? remaining)
       (#try.Success output)
@@ -116,8 +116,8 @@
 
 (def: #export (children parser)
   (All [a] (-> (Parser a) (Parser a)))
-  (function (_ docs)
-    (case docs
+  (function (_ documents)
+    (case documents
       #.Nil
       (exception.throw ..empty_input [])
       
@@ -128,23 +128,19 @@
         
         (#/.Node _tag _attributes children)
         (do try.monad
-          [output (run' parser children)]
+          [output (..run parser children)]
           (wrap [tail output]))))))
 
 (def: #export ignore
   (Parser Any)
-  (function (_ docs)
-    (case docs
+  (function (_ documents)
+    (case documents
       #.Nil
       (exception.throw ..empty_input [])
       
       (#.Cons head tail)
       (#try.Success [tail []]))))
 
-(def: #export (run parser document)
-  (All [a] (-> (Parser a) XML (Try a)))
-  (..run' parser (list document)))
-
 (exception: #export nowhere)
 
 (def: #export (somewhere parser)
diff --git a/stdlib/source/lux/debug.lux b/stdlib/source/lux/debug.lux
index 088504f2d..b60d62c11 100644
--- a/stdlib/source/lux/debug.lux
+++ b/stdlib/source/lux/debug.lux
@@ -22,14 +22,16 @@
     [collection
      ["." array]
      ["." list ("#\." functor)]]]
-   [time
-    [instant (#+ Instant)]
-    [duration (#+ Duration)]
-    [date (#+ Date)]]
+   ["." meta
+    ["." location]]
    [macro
     ["." template]
     ["." syntax (#+ syntax:)]
-    ["." code]]])
+    ["." code]]
+   [time
+    [instant (#+ Instant)]
+    [duration (#+ Duration)]
+    [date (#+ Date)]]])
 
 (with_expansions [<jvm> (as_is (import: java/lang/String)
 
@@ -161,7 +163,8 @@
   (exception.report
    ["Type" (%.type type)]))
 
-(type: Representation (-> Any Text))
+(type: Representation
+  (-> Any Text))
 
 (def: primitive_representation
   (Parser Representation)
@@ -304,3 +307,14 @@
               "Useful for debugging.")}
   (-> Text Any)
   ("lux io log" message))
+
+(exception: #export (type_hole {location Location} {type Type})
+  (exception.report
+   ["Location" (location.format location)]
+   ["Type" (%.type type)]))
+
+(syntax: #export (:hole)
+  (do meta.monad
+    [location meta.location
+     expectedT meta.expected_type]
+    (meta.fail (exception.construct ..type_hole [location expectedT]))))
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/js/case.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/js/case.lux
index 1c45a95b5..38f5125ea 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/js/case.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/js/case.lux
@@ -304,27 +304,19 @@
                           pattern_matching!)
               (_.throw (_.string ////synthesis/case.pattern_matching_error))))))
 
-(def: #export (case statement expression archive [valueS pathP])
-  (-> Phase! (Generator [Synthesis Path]))
-  (do ///////phase.monad
-    [stack_init (expression archive valueS)
-     pattern_matching! (pattern_matching statement expression archive pathP)
-     #let [closure (<| (_.closure (list))
-                       ($_ _.then
-                           (_.declare @temp)
-                           (_.define @cursor (_.array (list stack_init)))
-                           (_.define @savepoint (_.array (list)))
-                           pattern_matching!
-                           ))]]
-    (wrap (_.apply/* closure (list)))))
-
 (def: #export (case! statement expression archive [valueS pathP])
   (Generator! [Synthesis Path])
   (do ///////phase.monad
     [stack_init (expression archive valueS)
-     path! (pattern_matching statement expression archive pathP)]
+     pattern_matching! (pattern_matching statement expression archive pathP)]
     (wrap ($_ _.then
               (_.declare @temp)
               (_.define @cursor (_.array (list stack_init)))
               (_.define @savepoint (_.array (list)))
-              path!))))
+              pattern_matching!))))
+
+(def: #export (case statement expression archive [valueS pathP])
+  (-> Phase! (Generator [Synthesis Path]))
+  (do ///////phase.monad
+    [pattern_matching! (..case! statement expression archive [valueS pathP])]
+    (wrap (_.apply/* (_.closure (list) pattern_matching!) (list)))))
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python.lux
index 93300a02d..9ab6f4056 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python.lux
@@ -1,9 +1,13 @@
 (.module:
   [lux #*
    [abstract
-    [monad (#+ do)]]]
+    [monad (#+ do)]]
+   [control
+    ["." exception (#+ exception:)]]
+   [target
+    ["_" python]]]
   ["." / #_
-   [runtime (#+ Phase)]
+   [runtime (#+ Phase Phase!)]
    ["#." primitive]
    ["#." structure]
    ["#." reference]
@@ -21,7 +25,45 @@
        [reference (#+)
         [variable (#+)]]]]]]])
 
-(def: #export (generate archive synthesis)
+(exception: #export cannot-recur-as-an-expression)
+
+(def: (statement expression archive synthesis)
+  Phase!
+  (case synthesis
+    (^template [<tag>]
+      [(^ (<tag> value))
+       (//////phase\map _.return (expression archive synthesis))])
+    ([////synthesis.bit]
+     [////synthesis.i64]
+     [////synthesis.f64]
+     [////synthesis.text]
+     [////synthesis.variant]
+     [////synthesis.tuple]
+     [#////synthesis.Reference]
+     [////synthesis.branch/get]
+     [////synthesis.function/apply]
+     [#////synthesis.Extension])
+
+    (^ (////synthesis.branch/case case))
+    (/case.case! statement expression archive case)
+
+    (^ (////synthesis.branch/let let))
+    (/case.let! statement expression archive let)
+
+    (^ (////synthesis.branch/if if))
+    (/case.if! statement expression archive if)
+
+    (^ (////synthesis.loop/scope scope))
+    (/loop.scope! statement expression archive scope)
+
+    (^ (////synthesis.loop/recur updates))
+    (/loop.recur! statement expression archive updates)
+
+    (^ (////synthesis.function/abstraction abstraction))
+    (//////phase\map _.return (/function.function statement expression archive abstraction))
+    ))
+
+(def: #export (expression archive synthesis)
   Phase
   (case synthesis
     (^template [<tag> <generator>]
@@ -33,37 +75,41 @@
      [////synthesis.text /primitive.text])
 
     (^ (////synthesis.variant variantS))
-    (/structure.variant generate archive variantS)
+    (/structure.variant expression archive variantS)
 
     (^ (////synthesis.tuple members))
-    (/structure.tuple generate archive members)
+    (/structure.tuple expression archive members)
 
     (#////synthesis.Reference value)
     (//reference.reference /reference.system archive value)
 
     (^ (////synthesis.branch/case case))
-    (/case.case generate archive case)
+    (/case.case ..statement expression archive case)
 
     (^ (////synthesis.branch/let let))
-    (/case.let generate archive let)
+    (/case.let expression archive let)
 
     (^ (////synthesis.branch/if if))
-    (/case.if generate archive if)
+    (/case.if expression archive if)
 
     (^ (////synthesis.branch/get get))
-    (/case.get generate archive get)
+    (/case.get expression archive get)
 
     (^ (////synthesis.loop/scope scope))
-    (/loop.scope generate archive scope)
+    (/loop.scope ..statement expression archive scope)
 
     (^ (////synthesis.loop/recur updates))
-    (/loop.recur generate archive updates)
+    (//////phase.throw ..cannot-recur-as-an-expression [])
 
     (^ (////synthesis.function/abstraction abstraction))
-    (/function.function generate archive abstraction)
+    (/function.function ..statement expression archive abstraction)
 
     (^ (////synthesis.function/apply application))
-    (/function.apply generate archive application)
+    (/function.apply expression archive application)
 
     (#////synthesis.Extension extension)
-    (///extension.apply archive generate extension)))
+    (///extension.apply archive expression extension)))
+
+(def: #export generate
+  Phase
+  ..expression)
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/case.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/case.lux
index dfc327985..e3be48bc6 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/case.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/case.lux
@@ -17,7 +17,7 @@
    [target
     ["_" python (#+ Expression SVar Statement)]]]
   ["." // #_
-   ["#." runtime (#+ Operation Phase Generator)]
+   ["#." runtime (#+ Operation Phase Generator Phase! Generator!)]
    ["#." reference]
    ["#." primitive]
    ["/#" // #_
@@ -43,28 +43,47 @@
   (-> Register SVar)
   (|>> (///reference.foreign //reference.system) :assume))
 
-(def: #export (let generate archive [valueS register bodyS])
+(def: #export (let expression archive [valueS register bodyS])
   (Generator [Synthesis Register Synthesis])
   (do ///////phase.monad
-    [valueO (generate archive valueS)
-     bodyO (generate archive bodyS)]
+    [valueO (expression archive valueS)
+     bodyO (expression archive bodyS)]
     ## TODO: Find some way to do 'let' without paying the price of the closure.
     (wrap (_.apply/* (_.lambda (list (..register register))
                                bodyO)
                      (list valueO)))))
 
-(def: #export (if generate archive [testS thenS elseS])
+(def: #export (let! statement expression archive [valueS register bodyS])
+  (Generator! [Synthesis Register Synthesis])
+  (do ///////phase.monad
+    [valueO (expression archive valueS)
+     bodyO (statement expression archive bodyS)]
+    (wrap ($_ _.then
+              (_.set (list (..register register)) valueO)
+              bodyO))))
+
+(def: #export (if expression archive [testS thenS elseS])
   (Generator [Synthesis Synthesis Synthesis])
   (do ///////phase.monad
-    [testO (generate archive testS)
-     thenO (generate archive thenS)
-     elseO (generate archive elseS)]
+    [testO (expression archive testS)
+     thenO (expression archive thenS)
+     elseO (expression archive elseS)]
     (wrap (_.? testO thenO elseO))))
 
-(def: #export (get generate archive [pathP valueS])
+(def: #export (if! statement expression archive [testS thenS elseS])
+  (Generator! [Synthesis Synthesis Synthesis])
+  (do ///////phase.monad
+    [test! (expression archive testS)
+     then! (statement expression archive thenS)
+     else! (statement expression archive elseS)]
+    (wrap (_.if test!
+            then!
+            else!))))
+
+(def: #export (get expression archive [pathP valueS])
   (Generator [(List Member) Synthesis])
   (do ///////phase.monad
-    [valueO (generate archive valueS)]
+    [valueO (expression archive valueS)]
     (wrap (list\fold (function (_ side source)
                        (.let [method (.case side
                                        (^template [<side> <accessor>]
@@ -139,12 +158,12 @@
           ..restore!
           post!)))
 
-(def: (pattern_matching' generate archive)
-  (-> Phase Archive Path (Operation (Statement Any)))
+(def: (pattern_matching' statement expression archive)
+  (-> Phase! Phase Archive Path (Operation (Statement Any)))
   (function (recur pathP)
     (.case pathP
       (^ (/////synthesis.path/then bodyS))
-      (///////phase\map _.return (generate archive bodyS))
+      (statement expression archive bodyS)
 
       #/////synthesis.Pop
       (///////phase\wrap ..pop!)
@@ -239,16 +258,16 @@
       ([/////synthesis.path/seq _.then]
        [/////synthesis.path/alt ..alternation]))))
 
-(def: (pattern_matching generate archive pathP)
-  (-> Phase Archive Path (Operation (Statement Any)))
+(def: (pattern_matching statement expression archive pathP)
+  (-> Phase! Phase Archive Path (Operation (Statement Any)))
   (do ///////phase.monad
-    [pattern_matching! (pattern_matching' generate archive pathP)]
+    [pattern_matching! (pattern_matching' statement expression archive pathP)]
     (wrap ($_ _.then
               (_.while (_.bool true)
                        pattern_matching!)
               (_.raise (_.Exception/1 (_.string case.pattern_matching_error)))))))
 
-(def: (gensym prefix)
+(def: #export (gensym prefix)
   (-> Text (Operation SVar))
   (///////phase\map (|>> %.nat (format prefix) _.var) /////generation.next))
 
@@ -265,20 +284,26 @@
                      (#///////variable.Foreign register)
                      (..capture register))))))
 
-(def: #export (case generate archive [valueS pathP])
-  (Generator [Synthesis Path])
+(def: #export (case! statement expression archive [valueS pathP])
+  (Generator! [Synthesis Path])
+  (do ///////phase.monad
+    [stack_init (expression archive valueS)
+     pattern_matching! (pattern_matching statement expression archive pathP)]
+    (wrap ($_ _.then
+              (_.set (list @cursor) (_.list (list stack_init)))
+              (_.set (list @savepoint) (_.list (list)))
+              pattern_matching!
+              ))))
+
+(def: #export (case statement expression archive [valueS pathP])
+  (-> Phase! (Generator [Synthesis Path]))
   (do ///////phase.monad
-    [initG (generate archive valueS)
-     pattern_matching! (pattern_matching generate archive pathP)
+    [pattern_matching! (case! statement expression archive [valueS pathP])
      @case (..gensym "case")
-     @init (..gensym "init")
-     #let [@dependencies+ (..dependencies pathP)
-           directive (_.def @case (list& @init @dependencies+)
-                            ($_ _.then
-                                (_.set (list @cursor) (_.list (list @init)))
-                                (_.set (list @savepoint) (_.list (list)))
-                                pattern_matching!
-                                ))]
+     #let [@dependencies+ (..dependencies (/////synthesis.path/seq (/////synthesis.path/then valueS)
+                                                                   pathP))
+           directive (_.def @case @dependencies+
+                            pattern_matching!)]
      _ (/////generation.execute! directive)
      _ (/////generation.save! (_.code @case) directive)]
-    (wrap (_.apply/* @case (list& initG @dependencies+)))))
+    (wrap (_.apply/* @case @dependencies+))))
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/function.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/function.lux
index 8c97fec96..23619eafc 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/function.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/function.lux
@@ -11,9 +11,10 @@
    [target
     ["_" python (#+ SVar Expression Statement)]]]
   ["." // #_
-   [runtime (#+ Operation Phase Generator)]
+   [runtime (#+ Operation Phase Generator Phase! Generator!)]
    ["#." reference]
    ["#." case]
+   ["#." loop]
    ["/#" // #_
     ["#." reference]
     ["//#" /// #_
@@ -26,11 +27,11 @@
       [reference
        [variable (#+ Register Variable)]]]]]])
 
-(def: #export (apply generate archive [functionS argsS+])
+(def: #export (apply expression archive [functionS argsS+])
   (Generator (Application Synthesis))
   (do {! ///////phase.monad}
-    [functionO (generate archive functionS)
-     argsO+ (monad.map ! (generate archive) argsS+)]
+    [functionO (expression archive functionS)
+     argsO+ (monad.map ! (expression archive) argsS+)]
     (wrap (_.apply/* functionO argsO+))))
 
 (def: #export capture
@@ -62,16 +63,18 @@
 (def: input
   (|>> inc //case.register))
 
-(def: #export (function generate archive [environment arity bodyS])
-  (Generator (Abstraction Synthesis))
+(def: #export (function statement expression archive [environment arity bodyS])
+  (-> Phase! (Generator (Abstraction Synthesis)))
   (do {! ///////phase.monad}
-    [[function_name bodyO] (/////generation.with_new_context archive
+    [@expected_exception (//case.gensym "expected_exception")
+     @actual_exception (//case.gensym "actual_exception")
+     [function_name body!] (/////generation.with_new_context archive
                              (do !
                                [function_name (\ ! map ///reference.artifact
                                                  (/////generation.context archive))]
-                               (/////generation.with_anchor (_.var function_name)
-                                 (generate archive bodyS))))
-     environment (monad.map ! (generate archive) environment)
+                               (/////generation.with_anchor [1 @expected_exception]
+                                 (statement expression archive bodyS))))
+     environment (monad.map ! (expression archive) environment)
      #let [function_name (///reference.artifact function_name)
            @curried (_.var "curried")
            arityO (|> arity .int _.int)
@@ -91,9 +94,9 @@
              ($_ _.then
                  (_.set (list @num_args) (_.len/1 @curried))
                  (_.cond (list [(|> @num_args (_.= arityO))
-                                ($_ _.then
-                                    initialize!
-                                    (_.return bodyO))]
+                                (<| (_.then initialize!)
+                                    (//loop.set_scope @expected_exception @actual_exception)
+                                    body!)]
                                [(|> @num_args (_.> arityO))
                                 (let [arity_inputs (_.slice (_.int +0) arityO @curried)
                                       extra_inputs (_.slice arityO @num_args @curried)]
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/loop.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/loop.lux
index 7e92ddb74..563e8ee61 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/loop.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/loop.lux
@@ -7,15 +7,15 @@
     [text
      ["%" format (#+ format)]]
     [collection
-     ["." list ("#\." functor)]
+     ["." list ("#\." functor fold)]
      ["." set]]]
    [math
     [number
      ["n" nat]]]
    [target
-    ["_" python (#+ Expression SVar)]]]
+    ["_" python (#+ Expression SVar Statement)]]]
   ["." // #_
-   [runtime (#+ Operation Phase Generator)]
+   [runtime (#+ Operation Phase Generator Phase! Generator!)]
    ["#." case]
    ["//#" /// #_
     [synthesis
@@ -26,44 +26,89 @@
      ["//#" /// #_
       ["#." phase]
       [reference
-       ["#." variable]]]]]])
+       ["#." variable (#+ Register)]]]]]])
 
 (def: loop_name
   (-> Nat SVar)
   (|>> %.nat (format "loop") _.var))
 
-(def: #export (scope generate archive [start initsS+ bodyS])
-  (Generator (Scope Synthesis))
+(def: (setup offset bindings body)
+  (-> Register (List (Expression Any)) (Statement Any) (Statement Any))
+  (|> bindings
+      list.enumeration
+      (list\map (function (_ [register value])
+                  (_.set (list (//case.register (n.+ offset register)))
+                         value)))
+      list.reverse
+      (list\fold _.then body)))
+
+(def: #export (set_scope @expected_exception @actual_exception body!)
+  (-> SVar SVar (Statement Any) (Statement Any))
+  (let [exception_class (_.var "Exception")]
+    ($_ _.then
+        (_.set (list @expected_exception) (_.apply/* exception_class (list (_.string ""))))
+        (_.while (_.bool true)
+                 (_.try body!
+                        (list {#_.classes (list exception_class)
+                               #_.exception @actual_exception
+                               #_.handler (_.if (_.is @expected_exception @actual_exception)
+                                            _.continue
+                                            (_.raise @actual_exception))}))))))
+
+(def: #export (scope! statement expression archive [start initsS+ bodyS])
+  (Generator! (Scope Synthesis))
   (case initsS+
     ## function/false/non-independent loop
     #.Nil
-    (generate archive bodyS)
+    (statement expression archive bodyS)
+
+    ## true loop
+    _
+    (do {! ///////phase.monad}
+      [initsO+ (monad.map ! (expression archive) initsS+)
+       @expected_exception (//case.gensym "expected_exception")
+       @actual_exception (//case.gensym "actual_exception")
+       body! (/////generation.with_anchor [start @expected_exception]
+               (statement expression archive bodyS))]
+      (wrap (<| (..setup start initsO+)
+                (set_scope @expected_exception @actual_exception)
+                body!)))))
+
+(def: #export (scope statement expression archive [start initsS+ bodyS])
+  (-> Phase! (Generator (Scope Synthesis)))
+  (case initsS+
+    ## function/false/non-independent loop
+    #.Nil
+    (expression archive bodyS)
 
     ## true loop
     _
     (do {! ///////phase.monad}
       [@loop (\ ! map ..loop_name /////generation.next)
-       initsO+ (monad.map ! (generate archive) initsS+)
-       bodyO (/////generation.with_anchor @loop
-               (generate archive bodyS))
+       @expected_exception (//case.gensym "expected_exception")
+       @actual_exception (//case.gensym "actual_exception")
+       initsO+ (monad.map ! (expression archive) initsS+)
+       body! (/////generation.with_anchor [start @expected_exception]
+               (statement expression archive bodyS))
        #let [locals (|> initsS+
                         list.enumeration
                         (list\map (|>> product.left (n.+ start) //case.register)))
+             actual_loop (<| (_.def @loop locals)
+                             (set_scope @expected_exception @actual_exception)
+                             body!)
              [directive instantiation] (case (|> (synthesis.path/then bodyS)
                                                  //case.dependencies
                                                  (set.from_list _.hash)
                                                  (set.difference (set.from_list _.hash locals))
                                                  set.to_list)
                                          #.Nil
-                                         [(_.def @loop locals
-                                                 (_.return bodyO))
+                                         [actual_loop
                                           (_.apply/* @loop initsO+)]
 
                                          foreigns
                                          [(_.def @loop foreigns
                                                  ($_ _.then
-                                                     (_.def @loop locals
-                                                            (_.return bodyO))
+                                                     actual_loop
                                                      (_.return @loop)
                                                      ))
                                           (_.apply/* (_.apply/* @loop
@@ -73,9 +118,17 @@
        _ (/////generation.save! (_.code @loop) directive)]
       (wrap instantiation))))
 
-(def: #export (recur generate archive argsS+)
-  (Generator (List Synthesis))
+(def: #export (recur! statement expression archive argsS+)
+  (Generator! (List Synthesis))
   (do {! ///////phase.monad}
-    [@scope /////generation.anchor
-     argsO+ (monad.map ! (generate archive) argsS+)]
-    (wrap (_.apply/* @scope argsO+))))
+    [[offset @exception] /////generation.anchor
+     @temp (//case.gensym "lux_recur_values")
+     argsO+ (monad.map ! (expression archive) argsS+)
+     #let [re_binds (|> argsO+
+                        list.enumeration
+                        (list\map (function (_ [idx _])
+                                    (_.nth (_.int (.int idx)) @temp))))]]
+    (wrap ($_ _.then
+              (_.set (list @temp) (_.list argsO+))
+              (..setup offset re_binds
+                       (_.raise @exception))))))
diff --git a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/runtime.lux b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/runtime.lux
index 5ed9e7d2a..fc2e95789 100644
--- a/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/runtime.lux
+++ b/stdlib/source/lux/tool/compiler/language/lux/phase/generation/python/runtime.lux
@@ -27,17 +27,19 @@
    ["#." reference]
    ["//#" /// #_
     ["$" version]
-    ["#." synthesis]
+    ["#." synthesis (#+ Synthesis)]
     ["#." generation]
     ["//#" /// (#+ Output)
      ["#." phase]
+     [reference
+      [variable (#+ Register)]]
      [meta
       [archive (#+ Archive)
        ["." artifact (#+ Registry)]]]]]])
 
 (template [<name> <base>]
   [(type: #export <name>
-     (<base> SVar (Expression Any) (Statement Any)))]
+     (<base> [Register SVar] (Expression Any) (Statement Any)))]
 
   [Operation /////generation.Operation]
   [Phase /////generation.Phase]
@@ -45,12 +47,21 @@
   [Bundle /////generation.Bundle]
   )
 
+(type: #export Phase!
+  (-> Phase Archive Synthesis (Operation (Statement Any))))
+
+(type: #export (Generator! i)
+  (-> Phase! Phase Archive i (Operation (Statement Any))))
+
 (type: #export (Generator i)
   (-> Phase Archive i (Operation (Expression Any))))
 
-(def: prefix Text "LuxRuntime")
+(def: prefix
+  "LuxRuntime")
 
-(def: #export unit (_.string /////synthesis.unit))
+(def: #export
+  unit
+  (_.string /////synthesis.unit))
 
 (def: (flag value)
   (-> Bit Literal)
diff --git a/stdlib/source/lux/type.lux b/stdlib/source/lux/type.lux
index bcc71cd12..9372cc4e0 100644
--- a/stdlib/source/lux/type.lux
+++ b/stdlib/source/lux/type.lux
@@ -435,14 +435,3 @@
                         (~ (get@ #expression exemplar))}
                        {(~ extraction)
                         (:assume [])}))))))
-
-(exception: #export (hole_type {location Location} {type Type})
-  (exception.report
-   ["Location" (location.format location)]
-   ["Type" (..format type)]))
-
-(syntax: #export (:hole)
-  (do meta.monad
-    [location meta.location
-     expectedT meta.expected_type]
-    (meta.fail (exception.construct ..hole_type [location expectedT]))))
diff --git a/stdlib/source/lux/type/abstract.lux b/stdlib/source/lux/type/abstract.lux
index 2c7c00506..15534b996 100644
--- a/stdlib/source/lux/type/abstract.lux
+++ b/stdlib/source/lux/type/abstract.lux
@@ -7,7 +7,7 @@
    [control
     ["." exception (#+ exception:)]
     ["<>" parser ("#\." monad)
-     ["<c>" code (#+ Parser)]]]
+     ["<.>" code (#+ Parser)]]]
    [data
     ["." name ("#\." codec)]
     ["." text ("#\." equivalence monoid)]
@@ -170,8 +170,8 @@
 
 (def: cast
   (Parser [(Maybe Text) Code])
-  (<>.either (<>.and (<>.maybe <c>.local_identifier) <c>.any)
-             (<>.and (<>\wrap #.None) <c>.any)))
+  (<>.either (<>.and (<>.maybe <code>.local_identifier) <code>.any)
+             (<>.and (<>\wrap #.None) <code>.any)))
 
 (template [<name> <from> <to>]
   [(syntax: #export (<name> {[frame value] ..cast})
@@ -194,13 +194,13 @@
 (def: representation_definition_name
   (-> Text Text)
   (|>> ($_ text\compose
-           (name\encode (name_of #Representation))
+           (name\encode (name_of #..Representation))
            " ")))
 
 (def: declaration
   (Parser [Text (List Text)])
-  (<>.either (<c>.form (<>.and <c>.local_identifier (<>.some <c>.local_identifier)))
-             (<>.and <c>.local_identifier (\ <>.monad wrap (list)))))
+  (<>.either (<code>.form (<>.and <code>.local_identifier (<>.some <code>.local_identifier)))
+             (<>.and <code>.local_identifier (\ <>.monad wrap (list)))))
 
 ## TODO: Make sure the generated code always gets optimized away.
 ## (This applies to uses of ":abstraction" and ":representation")
@@ -209,7 +209,7 @@
                    {[name type_vars] declaration}
                    representation_type
                    {annotations (<>.default |annotations|.empty |annotations|.parser)}
-                   {primitives (<>.some <c>.any)})
+                   {primitives (<>.some <code>.any)})
   (do meta.monad
     [current_module meta.current_module_name
      #let [type_varsC (list\map code.local_identifier type_vars)
@@ -230,14 +230,39 @@
                      primitives
                      (list (` ((~! ..pop!)))))))))
 
-(syntax: #export (:transmutation value)
-  (wrap (list (` (..:abstraction (..:representation (~ value)))))))
-
-(syntax: #export (^:representation {name (<c>.form <c>.local_identifier)}
+(type: (Selection a)
+  (#Specific Code a)
+  (#Current a))
+
+(def: (selection parser)
+  (All [a] (-> (Parser a) (Parser (Selection a))))
+  (<>.or (<>.and <code>.any parser)
+         parser))
+
+(syntax: #export (:transmutation {selection (..selection <code>.any)})
+  (case selection
+    (#Specific specific value)
+    (wrap (list (` (..:abstraction (~ specific)
+                                   (..:representation (~ specific)
+                                                      (~ value))))))
+    
+    (#Current value)
+    (wrap (list (` (..:abstraction (..:representation (~ value))))))))
+
+(syntax: #export (^:representation {selection (<code>.form (..selection <code>.local_identifier))}
                                    body
-                                   {branches (<>.some <c>.any)})
-  (let [g!var (code.local_identifier name)]
-    (wrap (list& g!var
-                 (` (.let [(~ g!var) (..:representation (~ g!var))]
-                      (~ body)))
-                 branches))))
+                                   {branches (<>.some <code>.any)})
+  (case selection
+    (#Specific specific name)
+    (let [g!var (code.local_identifier name)]
+      (wrap (list& g!var
+                   (` (.let [(~ g!var) (..:representation (~ specific) (~ g!var))]
+                        (~ body)))
+                   branches)))
+    
+    (#Current name)
+    (let [g!var (code.local_identifier name)]
+      (wrap (list& g!var
+                   (` (.let [(~ g!var) (..:representation (~ g!var))]
+                        (~ body)))
+                   branches)))))
diff --git a/stdlib/source/program/aedifex/artifact/build.lux b/stdlib/source/program/aedifex/artifact/snapshot/build.lux
index d9a8b729e..d9a8b729e 100644
--- a/stdlib/source/program/aedifex/artifact/build.lux
+++ b/stdlib/source/program/aedifex/artifact/snapshot/build.lux
diff --git a/stdlib/source/program/aedifex/artifact/snapshot/stamp.lux b/stdlib/source/program/aedifex/artifact/snapshot/stamp.lux
new file mode 100644
index 000000000..c1efcc8ee
--- /dev/null
+++ b/stdlib/source/program/aedifex/artifact/snapshot/stamp.lux
@@ -0,0 +1,55 @@
+(.module:
+  [lux #*
+   [abstract
+    [equivalence (#+ Equivalence)]]
+   [data
+    ["." product]
+    [format
+     [xml (#+ XML)]]]]
+  ["." // #_
+   ["#." time (#+ Time)]
+   ["#." build (#+ Build)]])
+
+(type: #export Stamp
+  {#time Time
+   #build Build})
+
+(def: #export equivalence
+  (Equivalence Stamp)
+  ($_ product.equivalence
+      //time.equivalence
+      //build.equivalence
+      ))
+
+(def: time_format
+  (-> Time XML)
+  (|>> //time.format
+       #xml.Text
+       list
+       (#xml.Node ..tag xml.attributes)))
+
+(def: #export (format (^slots [#time #build]))
+  (-> Stamp (List XML))
+  (list (..time_format time)
+        (//build.format build)))
+
+(def: <timestamp>
+  xml.Tag
+  ["" "timestamp"])
+
+## (exception: #export (mismatch {expected Instant} {actual Instant})
+##   (exception.report
+##    ["Expected" (%.instant expected)]
+##    ["Actual" (%.instant actual)]))
+
+(def: time_parser
+  (Parser Time)
+  (do <>.monad
+    [_ (<xml>.node <timestamp>)]
+    (<text>.embed //time.parser
+                  (<xml>.children <xml>.text))))
+
+(def: #export parser
+  (Parser Stamp)
+  (<>.and (<xml>.somewhere ..time_parser)
+          (<xml>.somewhere //build.parser)))
diff --git a/stdlib/source/program/aedifex/artifact/snapshot/time.lux b/stdlib/source/program/aedifex/artifact/snapshot/time.lux
new file mode 100644
index 000000000..ea9bf3047
--- /dev/null
+++ b/stdlib/source/program/aedifex/artifact/snapshot/time.lux
@@ -0,0 +1,45 @@
+(.module:
+  [lux #*
+   [abstract
+    [equivalence (#+ Equivalence)]
+    [monad (#+ do)]]
+   [control
+    ["." exception (#+ exception:)]
+    ["<>" parser
+     ["<.>" text]
+     ["<.>" xml (#+ Parser)]]]
+   [data
+    [text
+     ["%" format]]
+    [format
+     ["." xml (#+ XML)]]]
+   [time
+    ["." instant (#+ Instant)]]]
+  ["." /// #_
+   [time
+    ["#." date]
+    ["#." time]]])
+
+(type: #export Time
+  Instant)
+
+(def: #export equivalence
+  (Equivalence Time)
+  instant.equivalence)
+
+(def: separator
+  ".")
+
+(def: #export (format value)
+  (%.Format Time)
+  (%.format (///date.format (instant.date value))
+            ..separator
+            (///time.format (instant.time value))))
+
+(def: #export parser
+  (<text>.Parser Time)
+  (do <>.monad
+    [date ///date.parser
+     _ (<text>.this ..separator)
+     time ///time.parser]
+    (wrap (instant.from_date_time date time))))
diff --git a/stdlib/source/program/aedifex/artifact/time_stamp.lux b/stdlib/source/program/aedifex/artifact/time_stamp.lux
deleted file mode 100644
index 0eab45a14..000000000
--- a/stdlib/source/program/aedifex/artifact/time_stamp.lux
+++ /dev/null
@@ -1,35 +0,0 @@
-(.module:
-  [lux #*
-   [abstract
-    [monad (#+ do)]]
-   [control
-    ["<>" parser
-     ["<.>" text (#+ Parser)]]]
-   [data
-    [text
-     ["%" format]]]
-   [time
-    ["." instant (#+ Instant)]]]
-  ["." / #_
-   ["#." date]
-   ["#." time]])
-
-(type: #export Time_Stamp
-  Instant)
-
-(def: #export separator
-  ".")
-
-(def: #export (format value)
-  (%.Format Time_Stamp)
-  (%.format (/date.format (instant.date value))
-            ..separator
-            (/time.format (instant.time value))))
-
-(def: #export parser
-  (Parser Time_Stamp)
-  (do <>.monad
-    [date /date.parser
-     _ (<text>.this ..separator)
-     time /time.parser]
-    (wrap (instant.from_date_time date time))))
diff --git a/stdlib/source/spec/lux/world/console.lux b/stdlib/source/spec/lux/world/console.lux
index f875cd07e..5bfcf1ff8 100644
--- a/stdlib/source/spec/lux/world/console.lux
+++ b/stdlib/source/spec/lux/world/console.lux
@@ -10,6 +10,9 @@
      ["!" capability]]
     [concurrency
      ["." promise (#+ Promise)]]]
+   [data
+    ["." text
+     ["%" format (#+ format)]]]
    [math
     ["." random]]]
   {1
@@ -22,19 +25,12 @@
         [message (random.ascii/alpha 10)]
         (wrap (do promise.monad
                 [console (promise.future console)
+                 ?write (!.use (\ console write) [(format message text.new_line)])
                  ?read (!.use (\ console read) [])
                  ?read_line (!.use (\ console read_line) [])
-                 ?write (!.use (\ console write) [message])
                  ?close/good (!.use (\ console close) [])
                  ?close/bad (!.use (\ console close) [])]
                 ($_ _.and'
-                    (_.cover' [/.Can_Read]
-                              (case [?read ?read_line]
-                                [(#try.Success _) (#try.Success _)]
-                                true
-
-                                _
-                                false))
                     (_.cover' [/.Can_Write]
                               (case ?write
                                 (#try.Success _)
@@ -42,6 +38,13 @@
                                 
                                 _
                                 false))
+                    (_.cover' [/.Can_Read]
+                              (case [?read ?read_line]
+                                [(#try.Success _) (#try.Success _)]
+                                true
+
+                                _
+                                false))
                     (_.cover' [/.Can_Close]
                               (case [?close/good ?close/bad]
                                 [(#try.Success _) (#try.Failure _)]
diff --git a/stdlib/source/test/aedifex/artifact/build.lux b/stdlib/source/test/aedifex/artifact/snapshot/build.lux
index d0920b44c..e3fdcab62 100644
--- a/stdlib/source/test/aedifex/artifact/build.lux
+++ b/stdlib/source/test/aedifex/artifact/snapshot/build.lux
@@ -11,23 +11,28 @@
     [parser
      ["<.>" xml]]]
    [math
-    ["." random]]]
+    ["." random (#+ Random)]]]
   {#program
    ["." /]})
 
+(def: #export random
+  (Random /.Build)
+  random.nat)
+
 (def: #export test
   Test
   (<| (_.covering /._)
       (_.for [/.Build]
              ($_ _.and
                  (_.for [/.equivalence]
-                        ($equivalence.spec /.equivalence random.nat))
+                        ($equivalence.spec /.equivalence ..random))
                  
                  (do random.monad
-                   [expected random.nat]
+                   [expected ..random]
                    (_.cover [/.format /.parser]
                             (|> expected
                                 /.format
+                                list
                                 (<xml>.run /.parser)
                                 (try\map (\ /.equivalence = expected))
                                 (try.default false))))
diff --git a/stdlib/source/test/aedifex/artifact/snapshot/stamp.lux b/stdlib/source/test/aedifex/artifact/snapshot/stamp.lux
new file mode 100644
index 000000000..aab722cad
--- /dev/null
+++ b/stdlib/source/test/aedifex/artifact/snapshot/stamp.lux
@@ -0,0 +1,48 @@
+(.module:
+  [lux #*
+   ["_" test (#+ Test)]
+   [abstract
+    [monad (#+ do)]
+    {[0 #spec]
+     [/
+      ["$." equivalence]]}]
+   [control
+    ["." try ("#\." functor)]
+    [parser
+     ["<.>" xml]]]
+   [math
+    ["." random (#+ Random)]]
+   [time
+    ["." instant]]]
+  {#program
+   ["." /]}
+  ["$." // #_
+   ["#." time]
+   ["#." build]])
+
+(def: #export random
+  (Random /.Stamp)
+  ($_ random.and
+      $//time.random
+      $//build.random
+      ))
+
+(def: #export test
+  Test
+  (<| (_.covering /._)
+      (_.for [/.Stamp])
+      ($_ _.and
+          (_.for [/.equivalence]
+                 ($equivalence.spec /.equivalence ..random))
+
+          (do random.monad
+            [expected ..random]
+            ($_ _.and
+                (_.cover [/.format /.parser]
+                         (|> expected
+                             /.format
+                             (<xml>.run' /.parser)
+                             (try\map (\ instant.equivalence = expected))
+                             (try.default false)))
+                ))
+          )))
diff --git a/stdlib/source/test/aedifex/artifact/snapshot/time.lux b/stdlib/source/test/aedifex/artifact/snapshot/time.lux
new file mode 100644
index 000000000..567c70ce4
--- /dev/null
+++ b/stdlib/source/test/aedifex/artifact/snapshot/time.lux
@@ -0,0 +1,42 @@
+(.module:
+  [lux #*
+   ["_" test (#+ Test)]
+   [abstract
+    [monad (#+ do)]
+    {[0 #spec]
+     [/
+      ["$." equivalence]]}]
+   [control
+    ["." try ("#\." functor)]
+    [parser
+     ["<.>" text]]]
+   [math
+    ["." random (#+ Random)]]
+   [time
+    ["." instant]]]
+  {#program
+   ["." /]})
+
+(def: #export random
+  (Random /.Time)
+  random.instant)
+
+(def: #export test
+  Test
+  (<| (_.covering /._)
+      (_.for [/.Time])
+      ($_ _.and
+          (_.for [/.equivalence]
+                 ($equivalence.spec /.equivalence ..random))
+
+          (do random.monad
+            [expected ..random]
+            ($_ _.and
+                (_.cover [/.format /.parser]
+                         (|> expected
+                             /.format
+                             (<text>.run /.parser)
+                             (try\map (\ instant.equivalence = expected))
+                             (try.default false)))
+                ))
+          )))
diff --git a/stdlib/source/test/aedifex/artifact/time_stamp.lux b/stdlib/source/test/aedifex/artifact/time_stamp.lux
deleted file mode 100644
index 7dea57392..000000000
--- a/stdlib/source/test/aedifex/artifact/time_stamp.lux
+++ /dev/null
@@ -1,33 +0,0 @@
-(.module:
-  [lux #*
-   ["_" test (#+ Test)]
-   [abstract
-    [monad (#+ do)]]
-   [control
-    ["." try ("#\." functor)]
-    [parser
-     ["<.>" text]]]
-   [math
-    ["." random (#+ Random)]
-    [number
-     ["n" nat]
-     ["i" int]]]
-   [time
-    ["." instant]]]
-  {#program
-   ["." /]})
-
-(def: #export test
-  Test
-  (<| (_.covering /._)
-      (_.for [/.Time_Stamp])
-      ($_ _.and
-          (do random.monad
-            [expected random.instant]
-            (_.cover [/.format /.parser]
-                     (|> expected
-                         /.format
-                         (<text>.run /.parser)
-                         (try\map (\ instant.equivalence = expected))
-                         (try.default false))))
-          )))
diff --git a/stdlib/source/test/lux/control/concurrency/actor.lux b/stdlib/source/test/lux/control/concurrency/actor.lux
index d983ab382..487e4c48c 100644
--- a/stdlib/source/test/lux/control/concurrency/actor.lux
+++ b/stdlib/source/test/lux/control/concurrency/actor.lux
@@ -32,9 +32,6 @@
   ((on_mail message state self)
    (message state self))
 
-  ((on_stop cause state)
-   (promise\wrap []))
-
   (message: (count! {increment Nat} state self Nat)
     (let [state' (n.+ increment state)]
       (promise\wrap (#try.Success [state' state']))))
@@ -90,9 +87,16 @@
                                            [actor (/.spawn! (: (/.Behavior Any Any)
                                                                {#/.on_init (|>>)
                                                                 #/.on_mail (function (_ message state self)
-                                                                             (message state self))
-                                                                #/.on_stop (function (_ cause state)
-                                                                             (promise.future (write cause)))})
+                                                                             (do {! promise.monad}
+                                                                               [outcome (message state self)]
+                                                                               (case outcome
+                                                                                 (#try.Failure cause)
+                                                                                 (do !
+                                                                                   [_ (promise.future (write cause))]
+                                                                                   (wrap outcome))
+                                                                                 
+                                                                                 (#try.Success _)
+                                                                                 (wrap outcome))))})
                                                             [])]
                                            (/.poison! actor)))
                        _ (promise.wait 100)
@@ -172,11 +176,7 @@
                                 [anonymous (/.actor {Nat
                                                      initial_state}
                                                     ((on_mail message state self)
-                                                     (message (inc state) self))
-
-                                                    ((on_stop cause state)
-                                                     (promise\wrap (exec (%.nat state)
-                                                                     []))))
+                                                     (message (inc state) self)))
                                  sent/inc? (/.mail! inc! anonymous)
                                  sent/dec? (/.mail! dec! anonymous)
                                  poisoned? (/.poison! anonymous)
diff --git a/stdlib/source/test/lux/control/parser/xml.lux b/stdlib/source/test/lux/control/parser/xml.lux
index a9f71af71..c2d0ac4e2 100644
--- a/stdlib/source/test/lux/control/parser/xml.lux
+++ b/stdlib/source/test/lux/control/parser/xml.lux
@@ -39,7 +39,7 @@
       [expected (random.ascii/alpha 1)]
       (_.cover [<exception>]
                (`` (and (~~ (template [<parser> <input>]
-                              [(|> (/.run <parser> <input>)
+                              [(|> (/.run <parser> (list <input>))
                                    (!expect (^multi (#try.Failure error)
                                                     (exception.match? <exception> error))))]
 
@@ -61,7 +61,7 @@
           (do {! random.monad}
             [expected (random.ascii/alpha 1)]
             (_.cover [/.run /.text]
-                     (|> (/.run /.text (#xml.Text expected))
+                     (|> (/.run /.text (list (#xml.Text expected)))
                          (!expect (^multi (#try.Success actual)
                                           (text\= expected actual))))))
           (!failure /.unconsumed_inputs
@@ -70,7 +70,7 @@
           (do {! random.monad}
             [expected (random.ascii/alpha 1)]
             (_.cover [/.ignore]
-                     (|> (/.run /.ignore (#xml.Text expected))
+                     (|> (/.run /.ignore (list (#xml.Text expected)))
                          (!expect (#try.Success [])))))
           (do {! random.monad}
             [expected ..random_tag]
@@ -79,7 +79,7 @@
                                   [actual /.tag
                                    _ /.ignore]
                                   (wrap (name\= expected actual)))
-                                (#xml.Node expected (dictionary.new name.hash) (list)))
+                                (list (#xml.Node expected (dictionary.new name.hash) (list))))
                          (!expect (#try.Success #1)))))
           (do {! random.monad}
             [expected ..random_tag]
@@ -87,7 +87,7 @@
                      (|> (/.run (do //.monad
                                   [_ (/.node expected)]
                                   /.ignore)
-                                (#xml.Node expected (dictionary.new name.hash) (list)))
+                                (list (#xml.Node expected (dictionary.new name.hash) (list))))
                          (!expect (#try.Success [])))))
           (!failure /.wrong_tag
                     [[(/.node ["" expected])
@@ -101,10 +101,10 @@
                                   [_ (/.node expected_tag)
                                    _ (/.attribute expected_attribute)]
                                   /.ignore)
-                                (#xml.Node expected_tag
-                                           (|> (dictionary.new name.hash)
-                                               (dictionary.put expected_attribute expected_value))
-                                           (list)))
+                                (list (#xml.Node expected_tag
+                                                 (|> (dictionary.new name.hash)
+                                                     (dictionary.put expected_attribute expected_value))
+                                                 (list))))
                          (!expect (#try.Success [])))))
           (!failure /.unknown_attribute
                     [[(do //.monad
@@ -123,11 +123,11 @@
                                    (do !
                                      [_ (/.node expected)]
                                      /.ignore)))
-                                (#xml.Node expected
-                                           (dictionary.new name.hash)
-                                           (list (#xml.Node expected
-                                                            (dictionary.new name.hash)
-                                                            (list)))))
+                                (list (#xml.Node expected
+                                                 (dictionary.new name.hash)
+                                                 (list (#xml.Node expected
+                                                                  (dictionary.new name.hash)
+                                                                  (list))))))
                          (!expect (#try.Success [])))))
           (!failure /.empty_input
                     [[(do //.monad
@@ -195,15 +195,15 @@
             ($_ _.and
                 (_.cover [/.somewhere]
                          (|> (/.run parser
-                                    (node parent
-                                          (list.concat (list (list.repeat repetitions (node wrong (list)))
-                                                             (list (node right (list)))
-                                                             (list.repeat repetitions (node wrong (list)))))))
+                                    (list (node parent
+                                                (list.concat (list (list.repeat repetitions (node wrong (list)))
+                                                                   (list (node right (list)))
+                                                                   (list.repeat repetitions (node wrong (list))))))))
                              (!expect (#try.Success []))))
                 (_.cover [/.nowhere]
                          (|> (/.run parser
-                                    (node parent
-                                          (list.repeat repetitions (node wrong (list)))))
+                                    (list (node parent
+                                                (list.repeat repetitions (node wrong (list))))))
                              (!expect (^multi (#try.Failure error)
                                               (exception.match? /.nowhere error)))))
                 ))
diff --git a/stdlib/source/test/lux/macro/template.lux b/stdlib/source/test/lux/macro/template.lux
index 53d7d114e..b129aaaef 100644
--- a/stdlib/source/test/lux/macro/template.lux
+++ b/stdlib/source/test/lux/macro/template.lux
@@ -3,9 +3,15 @@
    ["_" test (#+ Test)]
    [abstract
     [monad (#+ do)]]
+   [control
+    ["." try]
+    ["." exception]]
    [data
     [collection
      ["." list]]]
+   ["." macro
+    [syntax (#+ syntax:)]
+    ["." code]]
    [math
     ["." random (#+ Random)]
     [number
@@ -19,6 +25,15 @@
     (-> Nat Nat)
     (|>> !pow/2)))
 
+(syntax: (macro_error macro)
+  (function (_ compiler)
+    (case ((macro.expand macro) compiler)
+      (#try.Failure error)
+      (#try.Success [compiler (list (code.text error))])
+      
+      (#try.Success _)
+      (#try.Failure "OOPS!"))))
+
 (def: #export test
   Test
   (<| (_.covering /._)
@@ -97,5 +112,15 @@
                                          can_refer!
                                          can_shadow!)))
                                 ))))
+              (_.cover [/.irregular_arguments]
+                       (/.with [(arity/3 <0> <1> <2>)
+                                ""]
+                         (exception.match? /.irregular_arguments
+                                           (macro_error (arity/3 "a" "b")))))
+              (_.cover [/.cannot_shadow_definition]
+                       (exception.match? /.cannot_shadow_definition
+                                         (macro_error (/.with [(macro_error <0> <1> <2>)
+                                                               ""]
+                                                        ""))))
               )))
       ))
diff --git a/stdlib/source/test/lux/type.lux b/stdlib/source/test/lux/type.lux
index 168ed29d1..70b13a382 100644
--- a/stdlib/source/test/lux/type.lux
+++ b/stdlib/source/test/lux/type.lux
@@ -17,6 +17,7 @@
   {1
    ["." / ("#\." equivalence)]}
   ["." / #_
+   ["#." abstract]
    ["#." check]
    ["#." dynamic]
    ["#." implicit]
@@ -164,6 +165,7 @@
                                         {(Maybe a) example}
                                         (List a)))))
 
+          /abstract.test
           /check.test
           /dynamic.test
           /implicit.test
diff --git a/stdlib/source/test/lux/type/abstract.lux b/stdlib/source/test/lux/type/abstract.lux
new file mode 100644
index 000000000..30ad27687
--- /dev/null
+++ b/stdlib/source/test/lux/type/abstract.lux
@@ -0,0 +1,110 @@
+(.module:
+  [lux #*
+   ["_" test (#+ Test)]
+   ["." meta]
+   [abstract
+    [monad (#+ do)]]
+   [control
+    ["." try]
+    ["." exception]]
+   [data
+    ["." text ("#\." equivalence)]]
+   ["." macro
+    [syntax (#+ syntax:)]
+    ["." code]
+    ["." template]]
+   ["." math
+    ["." random]
+    [number
+     ["n" nat]]]]
+  {1
+   ["." /]})
+
+(template.with_locals [g!Foo g!Bar]
+  (as_is (template [<syntax> <meta>]
+           [(syntax: (<syntax>)
+              (do meta.monad
+                [frame <meta>]
+                (wrap (list (code.text (get@ #/.name frame))))))]
+
+           [current /.current]
+           [specific (/.specific (template.text [g!Foo]))]
+           )
+
+         (syntax: (with_no_active_frames macro)
+           (function (_ compiler)
+             (let [verdict (case ((macro.expand macro) compiler)
+                             (#try.Failure error)
+                             (exception.match? /.no_active_frames error)
+                             
+                             (#try.Success _)
+                             false)]
+               (#try.Success [compiler (list (code.bit verdict))]))))
+
+         (with_expansions [no_current! (..with_no_active_frames (..current))
+                           no_specific! (..with_no_active_frames (..specific))]
+           (/.abstract: (g!Foo a)
+             Text
+
+             (/.abstract: (g!Bar a)
+               Nat
+
+               (def: #export test
+                 Test
+                 (<| (_.covering /._)
+                     (_.for [/.abstract:])
+                     (do random.monad
+                       [expected_foo (random.ascii/lower 5)
+                        expected_bar random.nat]
+                       ($_ _.and
+                           (_.cover [/.:abstraction]
+                                    (and (exec (: (g!Foo Text)
+                                                  (/.:abstraction g!Foo expected_foo))
+                                           true)
+                                         (exec (: (g!Bar Text)
+                                                  (/.:abstraction expected_bar))
+                                           true)))
+                           (_.cover [/.:representation]
+                                    (and (|> expected_foo
+                                             (/.:abstraction g!Foo)
+                                             (: (g!Foo Bit))
+                                             (/.:representation g!Foo)
+                                             (text\= expected_foo))
+                                         (|> (/.:abstraction expected_bar)
+                                             (: (g!Bar Bit))
+                                             /.:representation
+                                             (n.= expected_bar))))
+                           (_.cover [/.:transmutation]
+                                    (and (exec (|> expected_foo
+                                                   (/.:abstraction g!Foo)
+                                                   (: (g!Foo .Macro))
+                                                   (/.:transmutation g!Foo)
+                                                   (: (g!Foo .Lux)))
+                                           true)
+                                         (exec (|> (/.:abstraction expected_bar)
+                                                   (: (g!Bar .Macro))
+                                                   /.:transmutation
+                                                   (: (g!Bar .Lux)))
+                                           true)))
+                           (_.cover [/.^:representation]
+                                    (and (let [(/.^:representation g!Foo actual_foo)
+                                               (: (g!Foo .Module)
+                                                  (/.:abstraction g!Foo expected_foo))]
+                                           (text\= expected_foo actual_foo))
+                                         (let [(/.^:representation actual_bar)
+                                               (: (g!Bar .Module)
+                                                  (/.:abstraction expected_bar))]
+                                           (n.= expected_bar actual_bar))))
+                           (_.for [/.Frame]
+                                  ($_ _.and
+                                      (_.cover [/.current]
+                                               (text\= (template.text [g!Bar])
+                                                       (..current)))
+                                      (_.cover [/.specific]
+                                               (text\= (template.text [g!Foo])
+                                                       (..specific)))
+                                      (_.cover [/.no_active_frames]
+                                               (and no_current!
+                                                    no_specific!))
+                                      ))
+                           )))))))))