More efficient "let" and "exec" expressions.

47 files changed, 510 insertions, 456 deletions

diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/analysis/evaluation.lux b/stdlib/source/library/lux/meta/compiler/language/lux/analysis/evaluation.lux
index ba7dea6b9..376993dec 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/analysis/evaluation.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/analysis/evaluation.lux
@@ -34,13 +34,15 @@
      [///
       [meta
        ["[0]" archive (.only Archive)
-        ["[0]" module]]]]]]]])
+        ["[0]" module]
+        ["[0]" artifact]]]]]]]])
 
 (type .public Eval
-  (-> Archive Type Code (Operation Any)))
+  (-> Archive Type Code
+      (Operation Any)))
 
 (def evals
-  (Atom (Dictionary module.ID Nat))
+  (Atom (Dictionary module.ID artifact.ID))
   (atom.atom (dictionary.empty n.hash)))
 
 (def .public (evaluator analysis
@@ -79,4 +81,4 @@
                                                             (i64.or @eval)
                                                             (i64.left_shifted 32)))
                        (translation lux archive exprS))]
-            (translation.evaluate! [@module @eval] [{.#None} exprO]))))))
+            (translation.evaluate! [{.#None} exprO]))))))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/lua.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/lua.lux
index b5d02fc22..40c6978b1 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/lua.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/lua.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Analysis)
+  [lux (.except)
    ["[0]" ffi]
    [abstract
     ["[0]" monad (.only do)]]
@@ -28,7 +28,7 @@
    ["[0]" extension]
    [//
     ["[0]" phase]
-    ["[0]" analysis (.only Analysis Operation Phase Handler Bundle)
+    ["[0]" analysis (.only Operation Phase Handler Bundle)
      ["[1]/[0]" type]]]]])
 
 (def Nil
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/ruby.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/ruby.lux
index cf78288f8..532c98f27 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/ruby.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/analysis/ruby.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Analysis)
+  [lux (.except)
    ["[0]" ffi]
    [abstract
     ["[0]" monad (.only do)]]
@@ -28,7 +28,7 @@
    ["[0]" extension]
    [//
     ["[0]" phase]
-    ["[0]" analysis (.only Analysis Operation Phase Handler Bundle)
+    ["[0]" analysis (.only Operation Phase Handler Bundle)
      ["[1]/[0]" type]]]]])
 
 (def array::new
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/declaration/lux.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/declaration/lux.lux
index a20110788..1768bdd07 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/declaration/lux.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/declaration/lux.lux
@@ -74,12 +74,6 @@
       {try.#Failure error}
       (phase.failure error))))
 
-(def (context [@module @artifact])
-  (-> unit.ID
-      unit.ID)
-  ... TODO: Find a better way that doesn't rely on clever tricks.
-  [@module (n.- (++ @artifact) 0)])
-
 ... TODO: Inline "evaluate!'" into "evaluate!" ASAP
 (def (evaluate!' archive translation code//type codeS)
   (All (_ anchor expression declaration)
@@ -94,7 +88,7 @@
       id /////translation.next
       codeG (translation archive codeS)
       @module (/////translation.module_id module archive)
-      codeV (/////translation.evaluate! (..context [@module id]) [{.#None} codeG])]
+      codeV (/////translation.evaluate! [{.#None} codeG])]
      (in [code//type codeG codeV]))))
 
 (def .public (evaluate! archive type codeC)
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/translation/jvm/host.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/translation/jvm/host.lux
index 509d6dcf5..3441363b9 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/translation/jvm/host.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/translation/jvm/host.lux
@@ -833,7 +833,7 @@
             [1 _])
       body
       
-      [2 [@ {synthesis.#Control {synthesis.#Branch {synthesis.#Let _ 2 (synthesis.tuple @ (list _ hidden))}}}]]
+      [2 [@ {synthesis.#Control {synthesis.#Branch {synthesis.#Let [2 _] (synthesis.tuple @ (list _ hidden))}}}]]
       hidden
       
       [_ [@ {synthesis.#Control {synthesis.#Branch {synthesis.#When _ path}}}]]
@@ -926,9 +926,8 @@
              {synthesis.#Exec (without_fake_parameter before)
                               (without_fake_parameter after)}
              
-             {synthesis.#Let value register body}
-             {synthesis.#Let (without_fake_parameter value)
-                             (-- register)
+             {synthesis.#Let [register value] body}
+             {synthesis.#Let [(-- register) (without_fake_parameter value)]
                              (without_fake_parameter body)}
              
              {synthesis.#If when then else}
@@ -1069,8 +1068,8 @@
       (synthesis.branch/exec @ [this that])
       (synthesis.branch/exec @ [(again this) (again that)])
 
-      (synthesis.branch/let @ [inputS register outputS])
-      (synthesis.branch/let @ [(again inputS) register (again outputS)])
+      (synthesis.branch/let @ [[register inputS] outputS])
+      (synthesis.branch/let @ [[register (again inputS)] (again outputS)])
 
       (synthesis.branch/if @ [testS thenS elseS])
       (synthesis.branch/if @ [(again testS) (again thenS) (again elseS)])
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/function.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/function.lux
index 0c9b3b3ab..a7b3d400d 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/function.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/function.lux
@@ -182,11 +182,11 @@
            that (grow environment that)]
           (in (/.branch/exec @ [this that])))
         
-        {/.#Let [inputS register bodyS]}
+        {/.#Let [[register inputS] bodyS]}
         (do phase.monad
           [inputS' (grow environment inputS)
            bodyS' (grow environment bodyS)]
-          (in (/.branch/let @ [inputS' (++ register) bodyS'])))
+          (in (/.branch/let @ [[(++ register) inputS'] bodyS'])))
         
         {/.#If [testS thenS elseS]}
         (do phase.monad
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/loop.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/loop.lux
index 27ce06b25..43c75fc6a 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/loop.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/loop.lux
@@ -138,11 +138,11 @@
          that (again return? that)]
         (in (/.branch/exec @ [this that])))
 
-      (/.branch/let @ [input register body])
+      (/.branch/let @ [[register input] body])
       (do maybe.monad
         [input' (again false input)
          body' (again return? body)]
-        (in (/.branch/let @ [input' (register_optimization offset register) body'])))
+        (in (/.branch/let @ [[(register_optimization offset register) input'] body'])))
 
       (/.branch/if @ [input then else])
       (do maybe.monad
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/variable.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/variable.lux
index fd49b0350..53d9b2117 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/variable.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/variable.lux
@@ -145,9 +145,9 @@
                                     {/.#Exec (again this)
                                              (again that)}
                                     
-                                    {/.#Let input register output}
-                                    {/.#Let (again input)
-                                            (..prune redundant register)
+                                    {/.#Let [register input] output}
+                                    {/.#Let [(..prune redundant register)
+                                             (again input)]
                                             (again output)}
                                     
                                     {/.#If test then else}
@@ -393,7 +393,7 @@
             (in [redundancy
                  (/.branch/exec @ [this that])]))
           
-          {/.#Let input register output}
+          {/.#Let [register input] output}
           (do try.monad
             [[redundancy input] (optimization' [redundancy input])
              redundancy (..declare register redundancy)
@@ -404,7 +404,7 @@
             (in [(dictionary.lacks register redundancy)
                  [@ {/.#Control {/.#Branch (if redundant?
                                              {/.#Exec input (..remove_local register output)}
-                                             {/.#Let input register output})}}]]))
+                                             {/.#Let [register input] output})}}]]))
           
           {/.#If test then else}
           (do try.monad
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/when.lux
index fbe1a96b6..080905e7f 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/synthesis/when.lux
@@ -276,7 +276,7 @@
   (do phase.monad
     [body (/.with_new_local
             (synthesize archive body))]
-    (in (/.branch/let @ [input @variable body]))))
+    (in (/.branch/let @ [[@variable input] body]))))
 
 (def .public (synthesize_masking synthesize @ archive input @variable @output)
   (-> Phase Location Archive /.Term Register Register
@@ -455,7 +455,7 @@
           (/.branch/exec @ [before after])
           (list#mix for_synthesis synthesis_storage (list before after))
 
-          (/.branch/let @ [inputS register exprS])
+          (/.branch/let @ [[register inputS] exprS])
           (revised #dependencies
                    (set.union (|> synthesis_storage
                                   (revised #bindings (set.has register))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/c++/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/c++/when.lux
index 1f58294e5..7dda901f2 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/c++/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/c++/when.lux
@@ -37,53 +37,30 @@
     [reference
      [variable (.only Register)]]]]])
 
-(type (If of)
-  (Record
-   [#when of
-    #then of
-    #else of]))
-
 (def .public (if next archive it)
-  (Term If)
+  (Term synthesis.If)
   (do phase.monad
-    [when (next archive (the #when it))
-     then (next archive (the #then it))
-     else (next archive (the #else it))]
+    [when (next archive (the synthesis.#if_when it))
+     then (next archive (the synthesis.#if_then it))
+     else (next archive (the synthesis.#if_else it))]
     (in (_.? when then else))))
 
-(type (Let of)
-  (Record
-   [#input of
-    #register Register
-    #body of]))
-
-(def (sub_bindings body)
-  (-> synthesis.Term
-      [(List [Register synthesis.Term]) synthesis.Term])
-  (.when body
-    (synthesis.branch/let @ [input register body])
-    (.let [[tail body] (sub_bindings body)]
-      [(list.partial [register input] tail) body])
-
-    _
-    [(list) body]))
-
 (def .public (let next archive it)
-  (Term Let)
+  (Term synthesis.Let)
   (do [! phase.monad]
-    [.let [[tail body] (sub_bindings (the #body it))
-           head_binding (the #register it)]
+    [.let [[tail body] (synthesis.flat_let (the synthesis.#expression it))
+           context (the synthesis.#context it)]
      bindings (monad.each ! (function (_ [binding value])
                               (do !
                                 [value (next archive value)]
                                 (in (_.variable (//reference.local binding) //type.value value))))
-                          (list.partial [head_binding (the #input it)]
+                          (list.partial context
                                         tail))
      body (next archive body)]
     (in (_.on (list)
-              (_.lambda (.when head_binding
-                          0 (list)
-                          _ (list _.all_by_value))
+              (_.lambda (.when context
+                          [0 _] (list)
+                          [_ _] (list _.all_by_value))
                         (list)
                         {.#Some //type.value}
                         (list#mix _.then
@@ -91,29 +68,13 @@
                                   (list.reversed bindings))
                         )))))
 
-(type (Exec of)
-  (Record
-   [#before of
-    #after of]))
-
-(def (sub_statements after)
-  (-> synthesis.Term
-      [(List synthesis.Term) synthesis.Term])
-  (.when after
-    (synthesis.branch/exec @ [before after])
-    (.let [[tail after] (sub_statements after)]
-      [(list.partial before tail) after])
-
-    _
-    [(list) after]))
-
 (def .public (exec next archive it)
-  (Term Exec)
+  (Term synthesis.Exec)
   (do [! phase.monad]
-    [.let [[tail after] (sub_statements (the #after it))]
+    [.let [[tail after] (synthesis.flat_exec (the synthesis.#after it))]
      all_before (monad.each ! (|>> (next archive)
                                    (phase#each _.;))
-                            (list.partial (the #before it) tail))
+                            (list.partial (the synthesis.#before it) tail))
      after (next archive after)]
     (in (_.on (list)
               (_.lambda (list _.all_by_value)
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js.lux
index 2cf2b2b00..7cfa582ae 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js.lux
@@ -11,8 +11,9 @@
    [meta
     [macro
      ["^" pattern]]
-    [target
-     ["_" js]]]]]
+    [compiler
+     [target
+      ["_" js]]]]]]
  ["[0]" /
   [runtime (.only Phase Phase!)]
   ["[1][0]" primitive]
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/function.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/function.lux
index 39b5abf84..b4bf4fa40 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/function.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/function.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Analysis Synthesis function)
+  [lux (.except function)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -23,9 +23,9 @@
   ["/[1]" //
    ["[1][0]" reference]
    ["//[1]" ///
-    [analysis (.only Abstraction Reification Analysis)]
-    [synthesis (.only Synthesis)]
+    [analysis (.only Abstraction Reification)]
     ["[0]" phase (.use "[1]#[0]" monad)]
+    ["[0]" synthesis]
     ["[1][0]" translation]
     ["//[1]" ///
      [arity (.only Arity)]
@@ -39,7 +39,7 @@
         ["[1]" artifact]]]]]]]])
 
 (def .public (apply expression archive [functionS argsS+])
-  (Translator (Reification Synthesis))
+  (Translator (Reification synthesis.Term))
   (do [! phase.monad]
     [functionO (expression archive functionS)
      argsO+ (monad.each ! (expression archive) argsS+)]
@@ -77,7 +77,7 @@
   (format (///reference.artifact function_name) "_scope"))
 
 (def .public (function statement expression archive [environment arity bodyS])
-  (-> Phase! (Translator (Abstraction Synthesis)))
+  (-> Phase! (Translator (Abstraction synthesis.Term)))
   (do [! phase.monad]
     [dependencies (cache.dependencies archive bodyS)
      [function_name body!] (/////translation.with_new_context archive dependencies
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/loop.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/loop.lux
index 5747dfee9..50e19dcf6 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/loop.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/loop.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Scope Synthesis)
+  [lux (.except Scope)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -23,8 +23,8 @@
   [runtime (.only Operation Phase Phase! Translator Translator!)]
   ["[1][0]" when]
   ["///[1]" ////
-   [synthesis (.only Scope Synthesis)]
    ["[0]" phase]
+   ["[0]" synthesis (.only Scope)]
    ["[1][0]" translation]
    [///
     [reference
@@ -66,7 +66,7 @@
         (_.then (_.define $iteration (_.array bindings))))))
 
 (def .public (scope! statement expression archive [start initsS+ bodyS])
-  (Translator! (Scope Synthesis))
+  (Translator! (Scope synthesis.Term))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -88,7 +88,7 @@
                                  body!)))))))
 
 (def .public (scope statement expression archive [start initsS+ bodyS])
-  (-> Phase! (Translator (Scope Synthesis)))
+  (-> Phase! (Translator (Scope synthesis.Term)))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -104,7 +104,7 @@
   (_.var "lux_again_values"))
 
 (def .public (again! statement expression archive argsS+)
-  (Translator! (List Synthesis))
+  (Translator! (List synthesis.Term))
   (do [! phase.monad]
     [[offset @scope] /////translation.anchor
      argsO+ (monad.each ! (expression archive) argsS+)
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/structure.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/structure.lux
index 64680da6d..221425bbc 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/structure.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/structure.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Variant Tuple Synthesis)
+  [lux (.except Variant Tuple)
    [abstract
     ["[0]" monad (.only do)]]
    [meta
@@ -15,12 +15,12 @@
   ["[1][0]" primitive]
   ["///[1]" ////
    ["[0]" phase (.use "[1]#[0]" monad)]
-   ["[1][0]" synthesis (.only Synthesis)]
+   ["[0]" synthesis]
    [analysis
     [complex (.only Variant Tuple)]]]])
 
 (def .public (tuple translate archive elemsS+)
-  (Translator (Tuple Synthesis))
+  (Translator (Tuple synthesis.Term))
   (when elemsS+
     {.#End}
     (phase#in //runtime.unit)
@@ -34,7 +34,7 @@
       (in (_.array elemsT+)))))
 
 (def .public (variant translate archive [lefts right? valueS])
-  (Translator (Variant Synthesis))
+  (Translator (Variant synthesis.Term))
   (phase#each (//runtime.variant (_.i32 (.int lefts))
                                  (//runtime.flag right?))
               (translate archive valueS)))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/when.lux
index 52b734977..75754f0fc 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/js/when.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Synthesis when exec let if)
+  [lux (.except when exec let if)
    [abstract
     ["[0]" monad (.only do)]]
    [control
@@ -32,7 +32,7 @@
      ["[1]/[0]" when]]
     ["/[1]" //
      ["[0]" phase (.use "[1]#[0]" monad)]
-     ["[1][0]" synthesis (.only Synthesis Path)
+     ["[0]" synthesis (.only Path)
       [access
        ["[0]" member (.only Member)]]]
      ["//[1]" ///
@@ -45,16 +45,19 @@
   (-> Register Var)
   (|>> (///reference.local //reference.system) as_expected))
 
-(def .public (exec expression archive [this that])
-  (Translator [Synthesis Synthesis])
-  (do phase.monad
-    [this (expression archive this)
-     that (expression archive that)]
-    (in (|> (_.array (list this that))
+(def .public (exec next archive it)
+  (Translator (synthesis.Exec synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail after] (synthesis.flat_exec (the synthesis.#after it))]
+     all_before (monad.each ! (next archive)
+                            (list.partial (the synthesis.#before it) tail))
+     after (next archive after)]
+    (in (|> (_.array (list (_.array all_before)
+                           after))
             (_.at (_.int +1))))))
 
 (def .public (exec! statement expression archive [this that])
-  (Translator! [Synthesis Synthesis])
+  (Translator! (synthesis.Exec synthesis.Term))
   (do phase.monad
     [this (expression archive this)
      that (statement expression archive that)]
@@ -62,18 +65,26 @@
              (_.statement this)
              that))))
 
-(def .public (let expression archive [valueS register bodyS])
-  (Translator [Synthesis Register Synthesis])
-  (do phase.monad
-    [valueO (expression archive valueS)
-     bodyO (expression archive bodyS)]
+(def .public (let next archive it)
+  (Translator (synthesis.Let synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail body] (synthesis.flat_let (the synthesis.#expression it))
+           context (the synthesis.#context it)]
+     bindings (monad.each ! (function (_ [binding value])
+                              (phase#each (_.define (..register binding))
+                                          (next archive value)))
+                          (list.partial context
+                                        tail))
+     body (next archive body)]
     ... TODO: Find some way to do 'let' without paying the price of the closure.
-    (in (_.apply (_.closure (list (..register register))
-                            (_.return bodyO))
-                 (list valueO)))))
-
-(def .public (let! statement expression archive [valueS register bodyS])
-  (Translator! [Synthesis Register Synthesis])
+    (in (_.apply (<| (_.closure (list))
+                     (list#mix _.then
+                               (_.return body)
+                               (list.reversed bindings)))
+                 (list)))))
+
+(def .public (let! statement expression archive [[register valueS] bodyS])
+  (Translator! (synthesis.Let synthesis.Term))
   (do phase.monad
     [valueO (expression archive valueS)
      bodyO (statement expression archive bodyS)]
@@ -82,7 +93,7 @@
              bodyO))))
 
 (def .public (if expression archive [testS thenS elseS])
-  (Translator [Synthesis Synthesis Synthesis])
+  (Translator [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
     [testO (expression archive testS)
      thenO (expression archive thenS)
@@ -90,7 +101,7 @@
     (in (_.? testO thenO elseO))))
 
 (def .public (if! statement expression archive [testS thenS elseS])
-  (Translator! [Synthesis Synthesis Synthesis])
+  (Translator! [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
     [testO (expression archive testS)
      thenO (statement expression archive thenS)
@@ -100,7 +111,7 @@
           elseO))))
 
 (def .public (get expression archive [pathP valueS])
-  (Translator [(List Member) Synthesis])
+  (Translator [(List Member) synthesis.Term])
   (do phase.monad
     [valueO (expression archive valueS)]
     (in (list#mix (function (_ side source)
@@ -191,16 +202,16 @@
        (|> nextP
            again
            (of phase.monad each (|>> (_.then (<choice> true idx)) {.#Some})))])
-    ([/////synthesis.simple_left_side  ..left_choice]
-     [/////synthesis.simple_right_side ..right_choice])
+    ([synthesis.simple_left_side  ..left_choice]
+     [synthesis.simple_right_side ..right_choice])
 
-    (/////synthesis.member/left 0)
+    (synthesis.member/left 0)
     (phase#in {.#Some (push_cursor! (_.at (_.i32 +0) ..peek_cursor))})
 
     ... Extra optimization
-    (/////synthesis.path/seq
-     (/////synthesis.member/left 0)
-     (/////synthesis.!bind_top register thenP))
+    (synthesis.path/seq
+     (synthesis.member/left 0)
+     (synthesis.!bind_top register thenP))
     (do phase.monad
       [then! (again thenP)]
       (in {.#Some (all _.then
@@ -209,25 +220,25 @@
 
     ... Extra optimization
     (^.with_template [<pm> <getter>]
-      [(/////synthesis.path/seq
+      [(synthesis.path/seq
         (<pm> lefts)
-        (/////synthesis.!bind_top register thenP))
+        (synthesis.!bind_top register thenP))
        (do phase.monad
          [then! (again thenP)]
          (in {.#Some (all _.then
                           (_.define (..register register) (<getter> (_.i32 (.int lefts)) ..peek_cursor))
                           then!)}))])
-    ([/////synthesis.member/left  //runtime.tuple//left]
-     [/////synthesis.member/right //runtime.tuple//right])
+    ([synthesis.member/left  //runtime.tuple//left]
+     [synthesis.member/right //runtime.tuple//right])
 
-    (/////synthesis.!bind_top register thenP)
+    (synthesis.!bind_top register thenP)
     (do phase.monad
       [then! (again thenP)]
       (in {.#Some (all _.then
                        (_.define (..register register) ..peek_and_pop_cursor)
                        then!)}))
 
-    (/////synthesis.!multi_pop nextP)
+    (synthesis.!multi_pop nextP)
     (.let [[extra_pops nextP'] (////synthesis/when.count_pops nextP)]
       (do phase.monad
         [next! (again nextP')]
@@ -250,16 +261,16 @@
 
         {.#None}
         (.when pathP
-          {/////synthesis.#Then bodyS}
+          {synthesis.#Then bodyS}
           (statement expression archive bodyS)
 
-          {/////synthesis.#Pop}
+          {synthesis.#Pop}
           (phase#in pop_cursor!)
 
-          {/////synthesis.#Bind register}
+          {synthesis.#Bind register}
           (phase#in (_.define (..register register) ..peek_cursor))
 
-          {/////synthesis.#Bit_Fork when thenP elseP}
+          {synthesis.#Bit_Fork when thenP elseP}
           (do [! phase.monad]
             [then! (again thenP)
              else! (.when elseP
@@ -276,7 +287,7 @@
                     else!
                     then!))))
 
-          {/////synthesis.#I64_Fork item}
+          {synthesis.#I64_Fork item}
           (do [! phase.monad]
             [clauses (monad.each ! (function (_ [match then])
                                      (do !
@@ -299,20 +310,20 @@
                (in (_.switch ..peek_cursor
                              cases
                              {.#Some ..fail_pm!})))])
-          ([/////synthesis.#F64_Fork //primitive.f64]
-           [/////synthesis.#Text_Fork //primitive.text])
+          ([synthesis.#F64_Fork //primitive.f64]
+           [synthesis.#Text_Fork //primitive.text])
 
           (^.with_template [<complex> <choice>]
             [(<complex> idx)
              (phase#in (<choice> false idx))])
-          ([/////synthesis.side/left  ..left_choice]
-           [/////synthesis.side/right ..right_choice])
+          ([synthesis.side/left  ..left_choice]
+           [synthesis.side/right ..right_choice])
 
           (^.with_template [<pm> <getter>]
             [(<pm> lefts)
              (phase#in (push_cursor! (<getter> (_.i32 (.int lefts)) ..peek_cursor)))])
-          ([/////synthesis.member/left  //runtime.tuple//left]
-           [/////synthesis.member/right //runtime.tuple//right])
+          ([synthesis.member/left  //runtime.tuple//left]
+           [synthesis.member/right //runtime.tuple//right])
 
           (^.with_template [<tag> <combinator>]
             [(<tag> leftP rightP)
@@ -320,8 +331,8 @@
                [left! (again leftP)
                 right! (again rightP)]
                (in (<combinator> left! right!)))])
-          ([/////synthesis.path/seq _.then]
-           [/////synthesis.path/alt ..alternation]))))))
+          ([synthesis.path/seq _.then]
+           [synthesis.path/alt ..alternation]))))))
 
 (def (pattern_matching statement expression archive pathP)
   (-> Phase! Phase Archive Path (Operation Statement))
@@ -333,7 +344,7 @@
              (_.throw (_.string ////synthesis/when.pattern_matching_error))))))
 
 (def .public (when! statement expression archive [valueS pathP])
-  (Translator! [Synthesis Path])
+  (Translator! [synthesis.Term Path])
   (do phase.monad
     [stack_init (expression archive valueS)
      pattern_matching! (pattern_matching statement expression archive pathP)]
@@ -344,7 +355,7 @@
              pattern_matching!))))
 
 (def .public (when statement expression archive [valueS pathP])
-  (-> Phase! (Translator [Synthesis Path]))
+  (-> Phase! (Translator [synthesis.Term Path]))
   (do phase.monad
     [pattern_matching! (..when! statement expression archive [valueS pathP])]
     (in (_.apply (_.closure (list) pattern_matching!) (list)))))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux
index 5a8c50a16..7c0882b27 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux
@@ -19,7 +19,7 @@
     [binary (.only Binary)
      ["[0]" \\format]]
     ["[0]" text (.use "[1]#[0]" hash)
-     ["%" \\format (.only format)]]
+     ["%" \\format]]
     [collection
      ["[0]" array]
      ["[0]" dictionary (.only Dictionary)]
@@ -181,13 +181,15 @@
 (def .public host
   (IO [java/lang/ClassLoader //runtime.Host])
   (io (let [library (loader.new_library [])
-            loader (loader.memory library)]
+            loader (loader.memory library)
+            id (atom.atom 0)]
         [loader
          (is //runtime.Host
              (implementation
-              (def (evaluate context @it,valueG)
-                (of try.monad each product.left
-                    (..evaluate! library loader (format "E" (//runtime.class_name context)) @it,valueG)))
+              (def (evaluate @it,valueG)
+                (let [[id _] (io.run! (atom.update! ++ id))]
+                  (of try.monad each product.left
+                      (..evaluate! library loader (%.format "E" (%.nat id)) @it,valueG))))
               
               (def execute
                 (..execute! library loader))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/when.lux
index a21bfc7e3..38d434942 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/jvm/when.lux
@@ -291,7 +291,7 @@
                    (_.set_label @end)))))))
 
 (def .public (exec phase archive [this that])
-  (Translator [synthesis.Term synthesis.Term])
+  (Translator (synthesis.Exec synthesis.Term))
   (do phase.monad
     [this! (phase archive this)
      that! (phase archive that)]
@@ -300,8 +300,8 @@
              _.pop
              that!))))
 
-(def .public (let phase archive [inputS register bodyS])
-  (Translator [synthesis.Term Register synthesis.Term])
+(def .public (let phase archive [[register inputS] bodyS])
+  (Translator (synthesis.Let synthesis.Term))
   (do phase.monad
     [input! (phase archive inputS)
      body! (phase archive bodyS)]
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua.lux
index e05e41f83..1857be954 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua.lux
@@ -11,8 +11,9 @@
    [meta
     [macro
      ["^" pattern]]
-    [target
-     ["_" lua]]]]]
+    [compiler
+     [target
+      ["_" lua]]]]]]
  ["[0]" /
   [runtime (.only Phase)]
   ["[1][0]" primitive]
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/function.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/function.lux
index 38a769175..606631373 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/function.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/function.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Label Analysis Synthesis function)
+  [lux (.except Label function)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -23,8 +23,8 @@
   ["/[1]" //
    ["[1][0]" reference]
    ["//[1]" ///
-    [analysis (.only Abstraction Reification Analysis)]
-    [synthesis (.only Synthesis)]
+    [analysis (.only Abstraction Reification)]
+    ["[0]" synthesis]
     ["[0]" phase (.use "[1]#[0]" monad)]
     ["[1][0]" translation]
     ["//[1]" ///
@@ -39,7 +39,7 @@
       [variable (.only Register Variable)]]]]]])
 
 (def .public (apply expression archive [functionS argsS+])
-  (Translator (Reification Synthesis))
+  (Translator (Reification synthesis.Term))
   (do [! phase.monad]
     [functionO (expression archive functionS)
      argsO+ (monad.each ! (expression archive) argsS+)]
@@ -73,7 +73,7 @@
   (_.label (format (///reference.artifact function_name) "_scope")))
 
 (def .public (function statement expression archive [environment arity bodyS])
-  (-> Phase! (Translator (Abstraction Synthesis)))
+  (-> Phase! (Translator (Abstraction synthesis.Term)))
   (do [! phase.monad]
     [dependencies (cache.dependencies archive bodyS)
      [function_name body!] (/////translation.with_new_context archive dependencies
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/loop.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/loop.lux
index 60c1309a1..b12c5d271 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/loop.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/loop.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Label Scope Synthesis)
+  [lux (.except Label Scope)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -27,7 +27,7 @@
    ["[1][0]" reference]
    ["//[1]" ///
     ["[0]" phase]
-    ["[0]" synthesis (.only Scope Synthesis)]
+    ["[0]" synthesis (.only Scope)]
     ["[1][0]" translation]
     ["//[1]" ///
      [meta
@@ -56,8 +56,8 @@
            body))))
 
 (def .public (scope! statement expression archive as_expression? [start initsS+ bodyS])
-  ... (Translator! (Scope Synthesis))
-  (-> Phase! Phase Archive Bit (Scope Synthesis)
+  ... (Translator! (Scope synthesis.Term))
+  (-> Phase! Phase Archive Bit (Scope synthesis.Term)
       (Operation [(List Expression) Statement]))
   (when initsS+
     ... function/false/non-independent loop
@@ -80,7 +80,7 @@
                          body!))]))))
 
 (def .public (scope statement expression archive [start initsS+ bodyS])
-  (-> Phase! (Translator (Scope Synthesis)))
+  (-> Phase! (Translator (Scope synthesis.Term)))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -121,7 +121,7 @@
       (in (_.apply initsO+ instantiation)))))
 
 (def .public (again! statement expression archive argsS+)
-  (Translator! (List Synthesis))
+  (Translator! (List synthesis.Term))
   (do [! phase.monad]
     [[offset @scope] /////translation.anchor
      argsO+ (monad.each ! (expression archive) argsS+)]
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/structure.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/structure.lux
index d9ad51d0f..d3b266697 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/structure.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/structure.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Tuple Variant Synthesis)
+  [lux (.except Tuple Variant)
    [abstract
     ["[0]" monad (.only do)]]
    [meta
@@ -15,15 +15,15 @@
   ["[1][0]" primitive]
   ["///[1]" ////
    ["[0]" phase (.use "[1]#[0]" monad)]
-   ["[1][0]" synthesis (.only Synthesis)]
+   ["[0]" synthesis]
    [analysis
     [complex (.only Variant Tuple)]]]])
 
 (def .public (tuple phase archive elemsS+)
-  (Translator (Tuple Synthesis))
+  (Translator (Tuple synthesis.Term))
   (when elemsS+
     {.#End}
-    (phase#in (//primitive.text /////synthesis.unit))
+    (phase#in (//primitive.text synthesis.unit))
 
     {.#Item singletonS {.#End}}
     (phase archive singletonS)
@@ -34,6 +34,6 @@
         (phase#each _.array))))
 
 (def .public (variant phase archive [lefts right? valueS])
-  (Translator (Variant Synthesis))
+  (Translator (Variant synthesis.Term))
   (phase#each (//runtime.variant lefts right?)
               (phase archive valueS)))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/when.lux
index 9d31368af..18fb379f6 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/lua/when.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Synthesis when exec let if)
+  [lux (.except when exec let if)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -30,7 +30,7 @@
     ["/[1]" //
      ["[0]" phase (.use "[1]#[0]" monad)]
      ["[1][0]" translation]
-     ["[1][0]" synthesis (.only Synthesis Path)
+     ["[0]" synthesis (.only Path)
       [access
        ["[0]" member (.only Member)]]]
      ["//[1]" ///
@@ -40,55 +40,67 @@
        [archive (.only Archive)]]]]]]])
 
 (def .public register
-  (-> Register Var)
+  (-> Register
+      Var)
   (|>> (///reference.local //reference.system) as_expected))
 
 (def .public capture
-  (-> Register Var)
+  (-> Register
+      Var)
   (|>> (///reference.foreign //reference.system) as_expected))
 
-(def .public (exec expression archive [this that])
-  (Translator [Synthesis Synthesis])
-  (do phase.monad
-    [this (expression archive this)
-     that (expression archive that)]
-    (in (|> (_.array (list this that))
-            (_.item (_.int +2))))))
-
-(def .public (exec! statement expression archive [this that])
-  (Translator! [Synthesis Synthesis])
+(def .public (exec next archive it)
+  (Translator (synthesis.Exec synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail after] (synthesis.flat_exec (the synthesis.#after it))]
+     all_before (monad.each ! (next archive)
+                            (list.partial (the synthesis.#before it) tail))
+     after (next archive after)]
+    (in (_.item (_.int +2)
+                (_.array (list (_.array all_before)
+                               after))))))
+
+(def .public (exec! statement next archive [this that])
+  (Translator! (synthesis.Exec synthesis.Term))
   (do [! phase.monad]
-    [this (expression archive this)
-     that (statement expression archive that)
+    [this (next archive this)
+     that (statement next archive that)
      $dummy (of ! each _.var (/////translation.symbol "_exec"))]
     (in (all _.then
              (_.set (list $dummy) this)
              that))))
 
-(def .public (let expression archive [valueS register bodyS])
-  (Translator [Synthesis Register Synthesis])
-  (do phase.monad
-    [valueO (expression archive valueS)
-     bodyO (expression archive bodyS)]
+(def .public (let next archive it)
+  (Translator (synthesis.Let synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail body] (synthesis.flat_let (the synthesis.#expression it))
+           context (the synthesis.#context it)]
+     bindings (monad.each ! (function (_ [binding value])
+                              (phase#each (_.local/1 (..register binding))
+                                          (next archive value)))
+                          (list.partial context
+                                        tail))
+     body (next archive body)]
     ... TODO: Find some way to do 'let' without paying the price of the closure.
-    (in (|> bodyO
-            _.return
-            (_.closure (list (..register register)))
-            (_.apply (list valueO))))))
+    (in (<| (_.apply (list))
+            (_.closure (list))
+            (list#mix _.then
+                      (_.return body)
+                      (list.reversed bindings))))))
 
-(def .public (let! statement expression archive [valueS register bodyS])
-  (Translator! [Synthesis Register Synthesis])
+(def .public (let! statement next archive [[register valueS] bodyS])
+  (Translator! (synthesis.Let synthesis.Term))
   (do phase.monad
-    [valueO (expression archive valueS)
-     bodyO (statement expression archive bodyS)]
+    [valueO (next archive valueS)
+     bodyO (statement next archive bodyS)]
     (in (all _.then
              (_.local/1 (..register register) valueO)
              bodyO))))
 
-(def .public (get expression archive [pathP valueS])
-  (Translator [(List Member) Synthesis])
+(def .public (get next archive [pathP valueS])
+  (Translator [(List Member) synthesis.Term])
   (do phase.monad
-    [valueO (expression archive valueS)]
+    [valueO (next archive valueS)]
     (in (list#mix (function (_ side source)
                     (.let [method (.if (the member.#right? side)
                                     (//runtime.tuple//right (_.int (.int (the member.#lefts side))))
@@ -97,24 +109,24 @@
                   valueO
                   pathP))))
 
-(def .public (if expression archive [testS thenS elseS])
-  (Translator [Synthesis Synthesis Synthesis])
+(def .public (if next archive [testS thenS elseS])
+  (Translator [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
-    [testO (expression archive testS)
-     thenO (expression archive thenS)
-     elseO (expression archive elseS)]
+    [testO (next archive testS)
+     thenO (next archive thenS)
+     elseO (next archive elseS)]
     (in (|> (_.if testO
               (_.return thenO)
               (_.return elseO))
             (_.closure (list))
             (_.apply (list))))))
 
-(def .public (if! statement expression archive [testS thenS elseS])
-  (Translator! [Synthesis Synthesis Synthesis])
+(def .public (if! statement next archive [testS thenS elseS])
+  (Translator! [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
-    [testO (expression archive testS)
-     thenO (statement expression archive thenS)
-     elseO (statement expression archive elseS)]
+    [testO (next archive testS)
+     thenO (statement next archive thenS)
+     elseO (statement next archive elseS)]
     (in (_.if testO
           thenO
           elseO))))
@@ -124,7 +136,8 @@
 (def @temp (_.var "lux_pm_temp"))
 
 (def (push! value)
-  (-> Expression Statement)
+  (-> Expression
+      Statement)
   (_.statement (|> (_.var "table.insert") (_.apply (list @cursor value)))))
 
 (def peek_and_pop
@@ -158,7 +171,8 @@
 
 (with_template [<name> <flag>]
   [(def (<name> simple? idx)
-     (-> Bit Nat Statement)
+     (-> Bit Nat
+         Statement)
      (all _.then
           (_.set (list @temp) (//runtime.sum//get ..peek <flag>
                                                   (|> idx .int _.int)))
@@ -174,7 +188,8 @@
   )
 
 (def (alternation pre! post!)
-  (-> Statement Statement Statement)
+  (-> Statement Statement
+      Statement)
   (all _.then
        (_.while (_.boolean true)
                 (all _.then
@@ -184,20 +199,21 @@
             ..restore!
             post!)))
 
-(def (pattern_matching' statement expression archive)
-  (-> Phase! Phase Archive Path (Operation Statement))
+(def (pattern_matching' statement next archive)
+  (-> Phase! Phase Archive Path
+      (Operation Statement))
   (function (again pathP)
     (.when pathP
-      {/////synthesis.#Then bodyS}
-      (statement expression archive bodyS)
+      {synthesis.#Then bodyS}
+      (statement next archive bodyS)
 
-      {/////synthesis.#Pop}
+      {synthesis.#Pop}
       (phase#in ..pop!)
 
-      {/////synthesis.#Bind register}
+      {synthesis.#Bind register}
       (phase#in (_.local/1 (..register register) ..peek))
 
-      {/////synthesis.#Bit_Fork when thenP elseP}
+      {synthesis.#Bit_Fork when thenP elseP}
       (do [! phase.monad]
         [then! (again thenP)
          else! (.when elseP
@@ -228,9 +244,9 @@
                            (_.if when then! else!))
                          ..fail!
                          clauses)))])
-      ([/////synthesis.#I64_Fork (<| _.int .int)]
-       [/////synthesis.#F64_Fork _.float]
-       [/////synthesis.#Text_Fork _.string])
+      ([synthesis.#I64_Fork (<| _.int .int)]
+       [synthesis.#F64_Fork _.float]
+       [synthesis.#Text_Fork _.string])
 
       (^.with_template [<complex> <simple> <choice>]
         [(<complex> idx)
@@ -238,19 +254,19 @@
 
          (<simple> idx nextP)
          (phase#each (_.then (<choice> true idx)) (again nextP))])
-      ([/////synthesis.side/left  /////synthesis.simple_left_side  ..left_choice]
-       [/////synthesis.side/right /////synthesis.simple_right_side ..right_choice])
+      ([synthesis.side/left  synthesis.simple_left_side  ..left_choice]
+       [synthesis.side/right synthesis.simple_right_side ..right_choice])
 
-      (/////synthesis.member/left 0)
+      (synthesis.member/left 0)
       (phase#in (|> ..peek (_.item (_.int +1)) ..push!))
       
       (^.with_template [<pm> <getter>]
         [(<pm> lefts)
          (phase#in (|> ..peek (<getter> (_.int (.int lefts))) ..push!))])
-      ([/////synthesis.member/left  //runtime.tuple//left]
-       [/////synthesis.member/right //runtime.tuple//right])
+      ([synthesis.member/left  //runtime.tuple//left]
+       [synthesis.member/right //runtime.tuple//right])
 
-      (/////synthesis.!bind_top register thenP)
+      (synthesis.!bind_top register thenP)
       (do phase.monad
         [then! (again thenP)]
         (phase#in (all _.then
@@ -263,20 +279,22 @@
            [pre! (again preP)
             post! (again postP)]
            (in (<combinator> pre! post!)))])
-      ([/////synthesis.path/seq _.then]
-       [/////synthesis.path/alt ..alternation]))))
+      ([synthesis.path/seq _.then]
+       [synthesis.path/alt ..alternation]))))
 
-(def (pattern_matching statement expression archive pathP)
-  (-> Phase! Phase Archive Path (Operation Statement))
+(def (pattern_matching statement next archive pathP)
+  (-> Phase! Phase Archive Path
+      (Operation Statement))
   (do phase.monad
-    [pattern_matching! (pattern_matching' statement expression archive pathP)]
+    [pattern_matching! (pattern_matching' statement next archive pathP)]
     (in (all _.then
              (_.while (_.boolean true)
                       pattern_matching!)
              (_.statement (|> (_.var "error") (_.apply (list (_.string ////synthesis/when.pattern_matching_error)))))))))
 
 (def .public dependencies
-  (-> Path (List Var))
+  (-> Path
+      (List Var))
   (|>> ////synthesis/when.storage
        (the ////synthesis/when.#dependencies)
        set.list
@@ -288,21 +306,22 @@
                       {///////variable.#Foreign register}
                       (..capture register))))))
 
-(def .public (when! statement expression archive [valueS pathP])
-  (Translator! [Synthesis Path])
+(def .public (when! statement next archive [valueS pathP])
+  (Translator! [synthesis.Term Path])
   (do phase.monad
-    [stack_init (expression archive valueS)
-     pattern_matching! (pattern_matching statement expression archive pathP)]
+    [stack_init (next archive valueS)
+     pattern_matching! (pattern_matching statement next archive pathP)]
     (in (all _.then
              (_.local (list @temp))
              (_.local/1 @cursor (_.array (list stack_init)))
              (_.local/1 @savepoint (_.array (list)))
              pattern_matching!))))
 
-(def .public (when statement expression archive [valueS pathP])
-  (-> Phase! (Translator [Synthesis Path]))
+(def .public (when statement next archive [valueS pathP])
+  (-> Phase!
+      (Translator [synthesis.Term Path]))
   (|> [valueS pathP]
-      (..when! statement expression archive)
+      (..when! statement next archive)
       (of phase.monad each
           (|>> (_.closure (list))
                (_.apply (list))))))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/function.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/function.lux
index 959c8a6d2..a17372cfe 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/function.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/function.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Analysis Synthesis function)
+  [lux (.except function)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -24,8 +24,8 @@
   ["/[1]" //
    ["[1][0]" reference]
    ["//[1]" ///
-    [analysis (.only Environment Abstraction Reification Analysis)]
-    [synthesis (.only Synthesis)]
+    [analysis (.only Environment Abstraction Reification)]
+    ["[0]" synthesis]
     ["[0]" phase]
     ["[1][0]" translation]
     ["//[1]" ///
@@ -40,7 +40,7 @@
         ["[1]" artifact]]]]]]]])
 
 (def .public (apply expression archive [functionS argsS+])
-  (Translator (Reification Synthesis))
+  (Translator (Reification synthesis.Term))
   (do [! phase.monad]
     [functionO (expression archive functionS)
      argsO+ (monad.each ! (expression archive) argsS+)]
@@ -75,7 +75,7 @@
   (|>> ++ //when.register))
 
 (def .public (function statement expression archive [environment arity bodyS])
-  (-> Phase! (Translator (Abstraction Synthesis)))
+  (-> Phase! (Translator (Abstraction synthesis.Term)))
   (do [! phase.monad]
     [dependencies (cache.dependencies archive bodyS)
      [[function_module function_artifact] body!] (/////translation.with_new_context archive dependencies
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/loop.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/loop.lux
index a74692875..d7a494c1a 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/loop.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/loop.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Scope Synthesis)
+  [lux (.except Scope)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -30,7 +30,7 @@
      ["[0]" when]]
     ["/[1]" //
      ["[0]" phase]
-     ["[0]" synthesis (.only Scope Synthesis)]
+     ["[0]" synthesis (.only Scope)]
      ["[1][0]" translation]
      ["//[1]" ///
       [meta
@@ -56,7 +56,7 @@
            {.#None}))
 
 (def .public (scope! statement expression archive [start initsS+ bodyS])
-  (Translator! (Scope Synthesis))
+  (Translator! (Scope synthesis.Term))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -73,7 +73,7 @@
               body!)))))
 
 (def .public (scope statement expression archive [start initsS+ bodyS])
-  (-> Phase! (Translator (Scope Synthesis)))
+  (-> Phase! (Translator (Scope synthesis.Term)))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -116,7 +116,7 @@
       (in (_.apply initsO+ instantiation)))))
 
 (def .public (again! statement expression archive argsS+)
-  (Translator! (List Synthesis))
+  (Translator! (List synthesis.Term))
   (do [! phase.monad]
     [offset /////translation.anchor
      @temp (//when.symbol "lux_again_values")
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/structure.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/structure.lux
index 0fbf74011..8fd7bfc0a 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/structure.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/structure.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Variant Tuple Synthesis)
+  [lux (.except Variant Tuple)
    [abstract
     ["[0]" monad (.only do)]]
    [meta
@@ -15,15 +15,15 @@
   ["[1][0]" primitive]
   ["///[1]" ////
    ["[0]" phase (.use "[1]#[0]" monad)]
-   ["[1][0]" synthesis (.only Synthesis)]
+   ["[0]" synthesis]
    [analysis
     [complex (.only Variant Tuple)]]]])
 
 (def .public (tuple translate archive elemsS+)
-  (Translator (Tuple Synthesis))
+  (Translator (Tuple synthesis.Term))
   (when elemsS+
     {.#End}
-    (phase#in (//primitive.text /////synthesis.unit))
+    (phase#in (//primitive.text synthesis.unit))
 
     {.#Item singletonS {.#End}}
     (translate archive singletonS)
@@ -34,6 +34,6 @@
         (phase#each _.list))))
 
 (def .public (variant translate archive [lefts right? valueS])
-  (Translator (Variant Synthesis))
+  (Translator (Variant synthesis.Term))
   (phase#each (//runtime.variant lefts right?)
               (translate archive valueS)))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/when.lux
index 79b6e192d..b86f3c9c6 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/python/when.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Synthesis when exec let if symbol)
+  [lux (.except when exec let if symbol)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -34,7 +34,7 @@
     ["/[1]" //
      ["[0]" phase (.use "[1]#[0]" monad)]
      ["[1][0]" translation]
-     ["[1][0]" synthesis (.only Synthesis Path)
+     ["[0]" synthesis (.only Path)
       [access
        ["[0]" member (.only Member)]]]
      ["//[1]" ///
@@ -59,8 +59,8 @@
   (-> Register SVar)
   (|>> (///reference.foreign //reference.system) as_expected)) 
 
-(def .public (let expression archive [valueS register bodyS])
-  (Translator [Synthesis Register Synthesis])
+(def .public (let expression archive [[register valueS] bodyS])
+  (Translator (synthesis.Let synthesis.Term))
   (do phase.monad
     [valueO (expression archive valueS)
      bodyO (expression archive bodyS)]
@@ -69,8 +69,8 @@
                  (_.lambda (list (..register register))
                            bodyO)))))
 
-(def .public (let! statement expression archive [valueS register bodyS])
-  (Translator! [Synthesis Register Synthesis])
+(def .public (let! statement expression archive [[register valueS] bodyS])
+  (Translator! (synthesis.Let synthesis.Term))
   (do phase.monad
     [valueO (expression archive valueS)
      bodyO (statement expression archive bodyS)]
@@ -78,15 +78,19 @@
              (_.set (list (..register register)) valueO)
              bodyO))))
 
-(def .public (exec expression archive [pre post])
-  (Translator [Synthesis Synthesis])
-  (do phase.monad
-    [pre (expression archive pre)
-     post (expression archive post)]
-    (in (_.item (_.int +1) (_.tuple (list pre post))))))
+(def .public (exec next archive it)
+  (Translator (synthesis.Exec synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail after] (synthesis.flat_exec (the synthesis.#after it))]
+     all_before (monad.each ! (next archive)
+                            (list.partial (the synthesis.#before it) tail))
+     after (next archive after)]
+    (in (_.item (_.int +1)
+                (_.tuple (list (_.tuple all_before)
+                               after))))))
 
 (def .public (exec! statement expression archive [pre post])
-  (Translator! [Synthesis Synthesis])
+  (Translator! (synthesis.Exec synthesis.Term))
   (do phase.monad
     [pre (expression archive pre)
      post (statement expression archive post)]
@@ -95,7 +99,7 @@
              post))))
 
 (def .public (if expression archive [testS thenS elseS])
-  (Translator [Synthesis Synthesis Synthesis])
+  (Translator [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
     [testO (expression archive testS)
      thenO (expression archive thenS)
@@ -103,7 +107,7 @@
     (in (_.? testO thenO elseO))))
 
 (def .public (if! statement expression archive [testS thenS elseS])
-  (Translator! [Synthesis Synthesis Synthesis])
+  (Translator! [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
     [test! (expression archive testS)
      then! (statement expression archive thenS)
@@ -113,7 +117,7 @@
           else!))))
 
 (def .public (get expression archive [pathP valueS])
-  (Translator [(List Member) Synthesis])
+  (Translator [(List Member) synthesis.Term])
   (do phase.monad
     [valueO (expression archive valueS)]
     (in (list#mix (function (_ side source)
@@ -206,7 +210,7 @@
   (-> (-> Path (Operation (Statement Any)))
       (-> Path (Operation (Maybe (Statement Any)))))
   (.when pathP
-    {/////synthesis.#Bit_Fork when thenP elseP}
+    {synthesis.#Bit_Fork when thenP elseP}
     (do [! phase.monad]
       [then! (again thenP)
        else! (.when elseP
@@ -236,9 +240,9 @@
                                  (_.if when then else))
                                ..fail_pm!
                                clauses)}))])
-    ([/////synthesis.#I64_Fork (<| //primitive.i64 .int)]
-     [/////synthesis.#F64_Fork (<| //primitive.f64)]
-     [/////synthesis.#Text_Fork (<| //primitive.text)])
+    ([synthesis.#I64_Fork (<| //primitive.i64 .int)]
+     [synthesis.#F64_Fork (<| //primitive.f64)]
+     [synthesis.#Text_Fork (<| //primitive.text)])
 
     _
     (of phase.monad in {.#None})))
@@ -254,13 +258,13 @@
 
         {.#None}
         (.when pathP
-          {/////synthesis.#Then bodyS}
+          {synthesis.#Then bodyS}
           (statement expression archive bodyS)
 
-          {/////synthesis.#Pop}
+          {synthesis.#Pop}
           (phase#in ..pop!)
 
-          {/////synthesis.#Bind register}
+          {synthesis.#Bind register}
           (phase#in (_.set (list (..register register)) ..peek))
 
           (^.with_template [<complex> <simple> <choice>]
@@ -271,26 +275,26 @@
              (|> nextP
                  again
                  (phase#each (_.then (<choice> true idx))))])
-          ([/////synthesis.side/left  /////synthesis.simple_left_side  ..left_choice]
-           [/////synthesis.side/right /////synthesis.simple_right_side ..right_choice])
+          ([synthesis.side/left  synthesis.simple_left_side  ..left_choice]
+           [synthesis.side/right synthesis.simple_right_side ..right_choice])
 
-          (/////synthesis.member/left 0)
+          (synthesis.member/left 0)
           (phase#in (|> ..peek (_.item (_.int +0)) ..push!))
           
           (^.with_template [<pm> <getter>]
             [(<pm> lefts)
              (phase#in (|> ..peek (<getter> (_.int (.int lefts))) ..push!))])
-          ([/////synthesis.member/left  //runtime.tuple::left]
-           [/////synthesis.member/right //runtime.tuple::right])
+          ([synthesis.member/left  //runtime.tuple::left]
+           [synthesis.member/right //runtime.tuple::right])
 
-          (/////synthesis.!bind_top register thenP)
+          (synthesis.!bind_top register thenP)
           (do !
             [then! (again thenP)]
             (phase#in (all _.then
                            (_.set (list (..register register)) ..peek_and_pop)
                            then!)))
 
-          (/////synthesis.!multi_pop nextP)
+          (synthesis.!multi_pop nextP)
           (.let [[extra_pops nextP'] (when.count_pops nextP)]
             (do !
               [next! (again nextP')]
@@ -298,13 +302,13 @@
                              (..multi_pop! (n.+ 2 extra_pops))
                              next!))))
 
-          (/////synthesis.path/seq preP postP)
+          (synthesis.path/seq preP postP)
           (do !
             [pre! (again preP)
              post! (again postP)]
             (in (_.then pre! post!)))
 
-          (/////synthesis.path/alt preP postP)
+          (synthesis.path/alt preP postP)
           (do !
             [pre! (again preP)
              post! (again postP)
@@ -338,7 +342,7 @@
                       (..capture register))))))
 
 (def .public (when! in_closure? statement expression archive [valueS pathP])
-  (-> Bit (Translator! [Synthesis Path]))
+  (-> Bit (Translator! [synthesis.Term Path]))
   (do phase.monad
     [stack_init (expression archive valueS)
      pattern_matching! (pattern_matching in_closure? statement expression archive pathP)]
@@ -349,7 +353,7 @@
              ))))
 
 (def .public (when statement expression archive [valueS pathP])
-  (-> Phase! (Translator [Synthesis Path]))
+  (-> Phase! (Translator [synthesis.Term Path]))
   (do phase.monad
     [dependencies (cache.path_dependencies archive pathP)
      [[when_module when_artifact] pattern_matching!] (/////translation.with_new_context
@@ -357,8 +361,8 @@
                                                        dependencies
                                                        (when! true statement expression archive [valueS pathP]))
      .let [@when (_.var (///reference.artifact [when_module when_artifact]))
-           @dependencies+ (..dependencies (/////synthesis.path/seq (/////synthesis.path/then valueS)
-                                                                   pathP))
+           @dependencies+ (..dependencies (synthesis.path/seq (synthesis.path/then valueS)
+                                                              pathP))
            declaration (_.def @when @dependencies+
                          pattern_matching!)]
      _ (/////translation.execute! declaration)
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby.lux
index 75e1a3957..4e5581db5 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby.lux
@@ -11,8 +11,9 @@
    [meta
     [macro
      ["^" pattern]]
-    [target
-     ["_" ruby]]]]]
+    [compiler
+     [target
+      ["_" ruby]]]]]]
  ["[0]" /
   [runtime (.only Phase Phase!)]
   ["[1][0]" primitive]
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/function.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/function.lux
index 237fa01b5..873c10419 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/function.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/function.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Analysis Synthesis function)
+  [lux (.except function)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -24,9 +24,9 @@
   ["/[1]" //
    ["[1][0]" reference]
    ["//[1]" ///
-    [synthesis (.only Synthesis)]
-    [analysis (.only Environment Abstraction Reification Analysis)]
+    [analysis (.only Environment Abstraction Reification)]
     ["[0]" phase]
+    ["[0]" synthesis]
     ["[1][0]" translation]
     ["//[1]" ///
      [arity (.only Arity)]
@@ -38,7 +38,7 @@
         ["[1]/[0]" artifact]]]]]]]])
 
 (def .public (apply expression archive [functionS argsS+])
-  (Translator (Reification Synthesis))
+  (Translator (Reification synthesis.Term))
   (do [! phase.monad]
     [functionO (expression archive functionS)
      argsO+ (monad.each ! (expression archive) argsS+)]
@@ -70,7 +70,7 @@
   (|>> ++ //when.register))
 
 (def .public (function statement expression archive [environment arity bodyS])
-  (-> Phase! (Translator (Abstraction Synthesis)))
+  (-> Phase! (Translator (Abstraction synthesis.Term)))
   (do [! phase.monad]
     [dependencies (cache/artifact.dependencies archive bodyS)
      [[function_module function_artifact] body!] (/////translation.with_new_context archive dependencies
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/loop.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/loop.lux
index dcb5d7ff6..4cff08fc6 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/loop.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/loop.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Scope Synthesis symbol)
+  [lux (.except Scope symbol)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -30,7 +30,7 @@
      ["[0]" when]]
     ["/[1]" //
      ["[0]" phase]
-     ["[0]" synthesis (.only Scope Synthesis)]
+     ["[0]" synthesis (.only Scope)]
      ["[1][0]" translation]
      ["//[1]" ///
       [reference
@@ -53,7 +53,7 @@
   (_.while (_.bool true)))
 
 (def .public (scope! statement expression archive [start initsS+ bodyS])
-  (Translator! (Scope Synthesis))
+  (Translator! (Scope synthesis.Term))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -70,7 +70,7 @@
               body!)))))
 
 (def .public (scope statement expression archive [start initsS+ bodyS])
-  (-> Phase! (Translator (Scope Synthesis)))
+  (-> Phase! (Translator (Scope synthesis.Term)))
   (when initsS+
     ... function/false/non-independent loop
     {.#End}
@@ -85,7 +85,7 @@
               (_.apply_lambda (list)))))))
 
 (def .public (again! statement expression archive argsS+)
-  (Translator! (List Synthesis))
+  (Translator! (List synthesis.Term))
   (do [! phase.monad]
     [offset /////translation.anchor
      @temp (//when.symbol "lux_again_values")
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/structure.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/structure.lux
index 72d870f54..e072193e6 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/structure.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/structure.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Variant Tuple Synthesis)
+  [lux (.except Variant Tuple)
    [abstract
     ["[0]" monad (.only do)]]
    [meta
@@ -15,15 +15,15 @@
   ["[1][0]" primitive]
   ["///[1]" ////
    ["[0]" phase (.use "[1]#[0]" monad)]
-   ["[1][0]" synthesis (.only Synthesis)]
+   ["[0]" synthesis]
    [analysis
     [complex (.only Variant Tuple)]]]])
 
 (def .public (tuple translate archive elemsS+)
-  (Translator (Tuple Synthesis))
+  (Translator (Tuple synthesis.Term))
   (when elemsS+
     {.#End}
-    (phase#in (//primitive.text /////synthesis.unit))
+    (phase#in (//primitive.text synthesis.unit))
 
     {.#Item singletonS {.#End}}
     (translate archive singletonS)
@@ -34,6 +34,6 @@
         (phase#each _.array))))
 
 (def .public (variant translate archive [lefts right? valueS])
-  (Translator (Variant Synthesis))
+  (Translator (Variant synthesis.Term))
   (phase#each (//runtime.variant lefts right?)
               (translate archive valueS)))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/when.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/when.lux
index cb897c7ff..add3c973a 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/when.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/translation/ruby/when.lux
@@ -3,7 +3,7 @@
 
 (.require
  [library
-  [lux (.except Synthesis when exec let if symbol)
+  [lux (.except when exec let if symbol)
    [abstract
     ["[0]" monad (.only do)]]
    [data
@@ -34,7 +34,7 @@
     ["/[1]" //
      ["[0]" phase (.use "[1]#[0]" monad)]
      ["[1][0]" translation]
-     ["[1][0]" synthesis (.only Synthesis Path)
+     ["[0]" synthesis (.only Path)
       [access
        ["[0]" member (.only Member)]]]
      ["//[1]" ///
@@ -55,16 +55,19 @@
   (-> Register LVar)
   (|>> (///reference.foreign //reference.system) as_expected))
 
-(def .public (exec expression archive [this that])
-  (Translator [Synthesis Synthesis])
-  (do phase.monad
-    [this (expression archive this)
-     that (expression archive that)]
-    (in (|> (_.array (list this that))
+(def .public (exec next archive it)
+  (Translator (synthesis.Exec synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail after] (synthesis.flat_exec (the synthesis.#after it))]
+     all_before (monad.each ! (next archive)
+                            (list.partial (the synthesis.#before it) tail))
+     after (next archive after)]
+    (in (|> (_.array (list (_.array all_before)
+                           after))
             (_.item (_.int +1))))))
 
 (def .public (exec! statement expression archive [this that])
-  (Translator! [Synthesis Synthesis])
+  (Translator! (synthesis.Exec synthesis.Term))
   (do phase.monad
     [this (expression archive this)
      that (statement expression archive that)]
@@ -73,19 +76,27 @@
              that
              ))))
 
-(def .public (let expression archive [valueS register bodyS])
-  (Translator [Synthesis Register Synthesis])
-  (do phase.monad
-    [valueO (expression archive valueS)
-     bodyO (expression archive bodyS)]
+(def .public (let next archive it)
+  (Translator (synthesis.Let synthesis.Term))
+  (do [! phase.monad]
+    [.let [[tail body] (synthesis.flat_let (the synthesis.#expression it))
+           context (the synthesis.#context it)]
+     bindings (monad.each ! (function (_ [binding value])
+                              (phase#each (_.set (list (..register binding)))
+                                          (next archive value)))
+                          (list.partial context
+                                        tail))
+     body (next archive body)]
     ... TODO: Find some way to do 'let' without paying the price of the closure.
-    (in (|> bodyO
-            _.return
-            [(list (..register register))] (_.lambda {.#None})
-            (_.apply_lambda (list valueO))))))
-
-(def .public (let! statement expression archive [valueS register bodyS])
-  (Translator! [Synthesis Register Synthesis])
+    (in (<| (_.apply_lambda (list))
+            (_.lambda {.#None})
+            [(list)
+             (list#mix _.then
+                       (_.return body)
+                       (list.reversed bindings))]))))
+
+(def .public (let! statement expression archive [[register valueS] bodyS])
+  (Translator! (synthesis.Let synthesis.Term))
   (do phase.monad
     [valueO (expression archive valueS)
      bodyO (statement expression archive bodyS)]
@@ -94,7 +105,7 @@
              bodyO))))
 
 (def .public (if expression archive [testS thenS elseS])
-  (Translator [Synthesis Synthesis Synthesis])
+  (Translator [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
     [testO (expression archive testS)
      thenO (expression archive thenS)
@@ -102,7 +113,7 @@
     (in (_.? testO thenO elseO))))
 
 (def .public (if! statement expression archive [testS thenS elseS])
-  (Translator! [Synthesis Synthesis Synthesis])
+  (Translator! [synthesis.Term synthesis.Term synthesis.Term])
   (do phase.monad
     [test! (expression archive testS)
      then! (statement expression archive thenS)
@@ -112,7 +123,7 @@
           else!))))
 
 (def .public (get expression archive [pathP valueS])
-  (Translator [(List Member) Synthesis])
+  (Translator [(List Member) synthesis.Term])
   (do phase.monad
     [valueO (expression archive valueS)]
     (in (list#mix (function (_ side source)
@@ -213,7 +224,7 @@
   (-> (-> Path (Operation Statement))
       (-> Path (Operation (Maybe Statement))))
   (.when pathP
-    {/////synthesis.#Bit_Fork when thenP elseP}
+    {synthesis.#Bit_Fork when thenP elseP}
     (do [! phase.monad]
       [then! (again thenP)
        else! (.when elseP
@@ -243,9 +254,9 @@
                                  (_.if when then else))
                                ..fail!
                                clauses)}))])
-    ([/////synthesis.#I64_Fork (<| //primitive.i64 .int)]
-     [/////synthesis.#F64_Fork (<| //primitive.f64)]
-     [/////synthesis.#Text_Fork (<| //primitive.text)])
+    ([synthesis.#I64_Fork (<| //primitive.i64 .int)]
+     [synthesis.#F64_Fork (<| //primitive.f64)]
+     [synthesis.#Text_Fork (<| //primitive.text)])
 
     _
     (of phase.monad in {.#None})))
@@ -261,16 +272,16 @@
         
         {.#None}
         (.when pathP
-          {/////synthesis.#Then bodyS}
+          {synthesis.#Then bodyS}
           (statement expression archive bodyS)
 
-          {/////synthesis.#Pop}
+          {synthesis.#Pop}
           (phase#in ..pop!)
 
-          {/////synthesis.#Bind register}
+          {synthesis.#Bind register}
           (phase#in (_.set (list (..register register)) ..peek))
 
-          {/////synthesis.#Bit_Fork when thenP elseP}
+          {synthesis.#Bit_Fork when thenP elseP}
           (do [! phase.monad]
             [then! (again thenP)
              else! (.when elseP
@@ -300,9 +311,9 @@
                                (_.if when then else))
                              ..fail!
                              clauses)))])
-          ([/////synthesis.#I64_Fork (<| //primitive.i64 .int)]
-           [/////synthesis.#F64_Fork (<| //primitive.f64)]
-           [/////synthesis.#Text_Fork (<| //primitive.text)])
+          ([synthesis.#I64_Fork (<| //primitive.i64 .int)]
+           [synthesis.#F64_Fork (<| //primitive.f64)]
+           [synthesis.#Text_Fork (<| //primitive.text)])
 
           (^.with_template [<complex> <simple> <choice>]
             [(<complex> idx)
@@ -312,26 +323,26 @@
              (|> nextP
                  again
                  (phase#each (_.then (<choice> true idx))))])
-          ([/////synthesis.side/left  /////synthesis.simple_left_side  ..left_choice]
-           [/////synthesis.side/right /////synthesis.simple_right_side ..right_choice])
+          ([synthesis.side/left  synthesis.simple_left_side  ..left_choice]
+           [synthesis.side/right synthesis.simple_right_side ..right_choice])
 
-          (/////synthesis.member/left 0)
+          (synthesis.member/left 0)
           (phase#in (|> ..peek (_.item (_.int +0)) ..push!))
           
           (^.with_template [<pm> <getter>]
             [(<pm> lefts)
              (phase#in (|> ..peek (<getter> (_.int (.int lefts))) ..push!))])
-          ([/////synthesis.member/left  //runtime.tuple//left]
-           [/////synthesis.member/right //runtime.tuple//right])
+          ([synthesis.member/left  //runtime.tuple//left]
+           [synthesis.member/right //runtime.tuple//right])
 
-          (/////synthesis.!bind_top register thenP)
+          (synthesis.!bind_top register thenP)
           (do phase.monad
             [then! (again thenP)]
             (phase#in (all _.then
                            (_.set (list (..register register)) ..peek_and_pop)
                            then!)))
 
-          (/////synthesis.!multi_pop nextP)
+          (synthesis.!multi_pop nextP)
           (.let [[extra_pops nextP'] (when.count_pops nextP)]
             (do phase.monad
               [next! (again nextP')]
@@ -339,7 +350,7 @@
                              (..multi_pop! (n.+ 2 extra_pops))
                              next!))))
 
-          (/////synthesis.path/seq preP postP)
+          (synthesis.path/seq preP postP)
           (do phase.monad
             [pre! (again preP)
              post! (again postP)]
@@ -347,7 +358,7 @@
                      pre!
                      post!)))
 
-          (/////synthesis.path/alt preP postP)
+          (synthesis.path/alt preP postP)
           (do phase.monad
             [pre! (again preP)
              post! (again postP)
@@ -367,7 +378,7 @@
              (_.statement (_.raise (_.string when.pattern_matching_error)))))))
 
 (def .public (when! in_closure? statement expression archive [valueS pathP])
-  (-> Bit (Translator! [Synthesis Path]))
+  (-> Bit (Translator! [synthesis.Term Path]))
   (do phase.monad
     [stack_init (expression archive valueS)
      pattern_matching! (pattern_matching in_closure? statement expression archive pathP)]
@@ -378,7 +389,7 @@
              ))))
 
 (def .public (when statement expression archive when)
-  (-> Phase! (Translator [Synthesis Path]))
+  (-> Phase! (Translator [synthesis.Term Path]))
   (|> when
       (when! true statement expression archive)
       (of phase.monad each
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/synthesis.lux b/stdlib/source/library/lux/meta/compiler/language/lux/synthesis.lux
index 2006f836f..d10fdd654 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/synthesis.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/synthesis.lux
@@ -94,13 +94,29 @@
    [#function s
     #arguments (List s)]))
 
-(type .public (Branch s)
+(type .public (Exec of)
+  (Record
+   [#before of
+    #after of]))
+
+(type .public (Let of)
+  (Record
+   [#context [Register of]
+    #expression of]))
+
+(type .public (If of)
+  (Record
+   [##if_when of
+    #if_then of
+    ##if_else of]))
+
+(type .public (Branch of)
   (Variant
-   {#Exec s s}
-   {#Let s Register s}
-   {#If s s s}
-   {#Get (List Member) s}
-   {#When s (Path' s)}))
+   {#Exec (Exec of)}
+   {#Let (Let of)}
+   {#If (If of)}
+   {#Get (List Member) of}
+   {#When of (Path' of)}))
 
 (type .public (Scope s)
   (Record
@@ -398,7 +414,7 @@
         (|> (format (%synthesis this) " " (%synthesis that))
             (text.enclosed ["{#exec " "}"]))
         
-        {#Let input register body}
+        {#Let [register input] body}
         (|> (format (%.nat register) " " (%synthesis input) " " (%synthesis body))
             (text.enclosed ["{#let " "}"]))
         
@@ -535,34 +551,34 @@
        (n.* 29 (of super hash body))
        ))))
 
-(def (branch_equivalence (open "#[0]"))
+(def (branch_equivalence (open "/#[0]"))
   (All (_ of)
     (-> (Equivalence of)
         (Equivalence (Branch of))))
   (implementation
    (def (= reference sample)
      (when [reference sample]
-       [{#Let [reference_input reference_register reference_body]}
-        {#Let [sample_input sample_register sample_body]}]
-       (and (#= reference_input sample_input)
+       [{#Let [[reference_register reference_input] reference_body]}
+        {#Let [[sample_register sample_input] sample_body]}]
+       (and (/#= reference_input sample_input)
             (n.= reference_register sample_register)
-            (#= reference_body sample_body))
+            (/#= reference_body sample_body))
 
        [{#If [reference_test reference_then reference_else]}
         {#If [sample_test sample_then sample_else]}]
-       (and (#= reference_test sample_test)
-            (#= reference_then sample_then)
-            (#= reference_else sample_else))
+       (and (/#= reference_test sample_test)
+            (/#= reference_then sample_then)
+            (/#= reference_else sample_else))
        
        [{#Get [reference_path reference_record]}
         {#Get [sample_path sample_record]}]
        (and (of (list.equivalence /member.equivalence) = reference_path sample_path)
-            (#= reference_record sample_record))
+            (/#= reference_record sample_record))
        
        [{#When [reference_input reference_path]}
         {#When [sample_input sample_path]}]
-       (and (#= reference_input sample_input)
-            (of (path'_equivalence #=) = reference_path sample_path))
+       (and (/#= reference_input sample_input)
+            (of (path'_equivalence /#=) = reference_path sample_path))
        
        _
        false))))
@@ -582,7 +598,7 @@
             (of super hash this)
             (of super hash that))
        
-       {#Let [input register body]}
+       {#Let [[register input] body]}
        (all n.* 3
             (of super hash input)
             (of n.hash hash register)
@@ -793,3 +809,25 @@
   [simple_left_side ..side/left]
   [simple_right_side ..side/right]
   )
+
+(def .public (flat_exec after)
+  (-> Term
+      [(List Term) Term])
+  (.when after
+    (branch/exec @ [before after])
+    (let [[tail after] (flat_exec after)]
+      [(list.partial before tail) after])
+
+    _
+    [(list) after]))
+
+(def .public (flat_let body)
+  (-> Term
+      [(List [Register Term]) Term])
+  (.when body
+    (branch/let @ [context body])
+    (let [[tail body] (flat_let body)]
+      [(list.partial context tail) body])
+
+    _
+    [(list) body]))
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/translation.lux b/stdlib/source/library/lux/meta/compiler/language/lux/translation.lux
index 0bf955402..9e14a005b 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/translation.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/translation.lux
@@ -61,7 +61,7 @@
 
 (type .public (Host expression declaration)
   (Interface
-   (is (-> unit.ID [(Maybe unit.ID) expression]
+   (is (-> [(Maybe unit.ID) expression]
            (Try Any))
        evaluate)
    (is (-> declaration
@@ -219,12 +219,12 @@
     (Operation anchor expression declaration descriptor.Module))
   (phase.read (the #module)))
 
-(def .public (evaluate! label code)
+(def .public (evaluate! code)
   (All (_ anchor expression declaration)
-    (-> unit.ID [(Maybe unit.ID) expression]
+    (-> [(Maybe unit.ID) expression]
         (Operation anchor expression declaration Any)))
   (function (_ state)
-    (when (of (the #host state) evaluate label code)
+    (when (of (the #host state) evaluate code)
       {try.#Success output}
       {try.#Success [state output]}
 
diff --git a/stdlib/source/library/lux/meta/compiler/meta/cache/dependency/artifact.lux b/stdlib/source/library/lux/meta/compiler/meta/cache/dependency/artifact.lux
index d6b3e055e..22a0bbf8a 100644
--- a/stdlib/source/library/lux/meta/compiler/meta/cache/dependency/artifact.lux
+++ b/stdlib/source/library/lux/meta/compiler/meta/cache/dependency/artifact.lux
@@ -113,7 +113,7 @@
               (references this)
               (references that))
         
-        {synthesis.#Let input _ body}
+        {synthesis.#Let [_ input] body}
         (.all list#composite
               (references input)
               (references body))
diff --git a/stdlib/source/library/lux/test/property.lux b/stdlib/source/library/lux/test/property.lux
index a8a1fe1d5..4744d780b 100644
--- a/stdlib/source/library/lux/test/property.lux
+++ b/stdlib/source/library/lux/test/property.lux
@@ -60,8 +60,7 @@
 
 (def .public context
   (-> Text Test Test)
-  (|>> %.text
-       //.context
+  (|>> //.context
        random#each))
 
 (def .public failure
diff --git a/stdlib/source/test/lux/math/number/i64.lux b/stdlib/source/test/lux/math/number/i64.lux
index 32c5a1717..d03f3c6b3 100644
--- a/stdlib/source/test/lux/math/number/i64.lux
+++ b/stdlib/source/test/lux/math/number/i64.lux
@@ -171,7 +171,10 @@
       (_.for [.I64])
       (do [! random.monad]
         [pattern random.nat
-         idx (of ! each (n.% /.width) random.nat)]
+         idx (of ! each (n.% /.width) random.nat)
+
+         left random.nat
+         right random.nat]
         (all _.and
              (_.coverage [/.width /.bits_per_byte /.bytes_per_i64]
                (and (n.= /.bytes_per_i64
@@ -201,7 +204,10 @@
                                 (/.not pattern)))
                     (/#= /.false
                          (/.xor pattern
-                                pattern))))
+                                pattern))
+                    (/#= (/.xor left right)
+                         (/.and (/.or left right)
+                                (/.not (/.and left right))))))
              (_.coverage [/.ones]
                (let [zero&one!
                      (if (/.one? idx pattern)
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/complex.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/complex.lux
index bf08c727a..66e5421b0 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/complex.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/complex.lux
@@ -77,8 +77,7 @@
          .let [extender (is extension.Extender
                             (function (_ _)
                               (undefined)))
-               phase (//.translate extender ..lux)
-               $unit [0 0]]])
+               phase (//.translate extender ..lux)]])
       (all _.and
            (_.coverage [/.variant]
              (`` (and (,, (with_template [<lefts> <right?> <synthesis> <expected> <=>]
@@ -91,7 +90,7 @@
                                          [_ (translation.set_buffer translation.empty_buffer)
                                           it (/.variant phase archive.empty
                                                         [<lefts> <right?> (<synthesis> location.dummy <expected>)])]
-                                         (in (when (of host evaluate $unit [{.#None} it])
+                                         (in (when (of host evaluate [{.#None} it])
                                                {try.#Success actual}
                                                (when (as Variant/3 actual)
                                                  {<lefts> <right?> actual}
@@ -120,7 +119,7 @@
                                       (list (synthesis.bit location.dummy expected_bit)
                                             (synthesis.i64 location.dummy expected_i64)
                                             (synthesis.text location.dummy expected_text)))]
-                         (in (when (of host evaluate $unit [{.#None} it])
+                         (in (when (of host evaluate [{.#None} it])
                                {try.#Success actual}
                                (let [[actual_bit actual_i64 actual_text] (as Tuple/3 actual)]
                                  (and (bit#= expected_bit actual_bit)
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function.lux
index 81cfb675e..906c23a71 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function.lux
@@ -28,6 +28,9 @@
     ["_" property (.only Test)]]]]
  [\\library
   ["[0]" / (.only)
+   [field
+    [constant
+     ["[0]" arity]]]
    ["[0]" // (.only)
     ["[0]" host]
     ["[0]" runtime]
@@ -58,11 +61,10 @@
          .let [extender (is extension.Extender
                             (function (_ _)
                               (undefined)))
-               phase (//.translate extender complexT.lux)
-               @ [module 0 0]
-               $unit [(-- 0) (-- 0)]]
+               next (//.translate extender complexT.lux)
+               @ [module 0 0]]
 
-         arity (of ! each (|>> (n.% 16) (n.+ 2)) random.nat)
+         arity (of ! each (|>> (n.% (-- arity.maximum)) (n.+ 2)) random.nat)
          inner_arity (of ! each (|>> (n.% arity) (n.+ 1)) random.nat)])
       (all _.and
            (_.coverage [/.abstraction]
@@ -75,11 +77,11 @@
                    (<| (phase.result state)
                        (do phase.monad
                          [_ (translation.set_buffer translation.empty_buffer)
-                          it (/.abstraction phase archive
+                          it (/.abstraction next archive
                                             [(list) 1 (synthesis.i64 @ expected_i64)])]
                          (in (|> it
                                  [{.#None}]
-                                 (of host evaluate $unit)
+                                 (of host evaluate)
                                  (try#each (|>> (as (-> [] I64))
                                                 (function.on [])
                                                 (i64#= expected_i64)))
@@ -96,12 +98,12 @@
                          (<| (phase.result state)
                              (do phase.monad
                                [_ (translation.set_buffer translation.empty_buffer)
-                                it (/.apply phase archive
+                                it (/.apply next archive
                                             [(synthesis.function/abstraction @ [(list) arity (synthesis.i64 @ expected_i64)])
                                              (list.repeated arity (synthesis.bit @ expected_bit))])]
                                (in (|> it
                                        [{.#None}]
-                                       (of host evaluate $unit)
+                                       (of host evaluate)
                                        (try#each (|>> (as I64)
                                                       (i64#= expected_i64)))
                                        (try.else false))))))
@@ -130,13 +132,15 @@
                                       outer_application (is synthesis.Term
                                                             (<| (synthesis.function/apply @)
                                                                 [outer_abstraction
-                                                                 (list.repeated outer_arity (synthesis.bit @ expected_bit))]))]
-                                it (/.apply phase archive
-                                            [outer_application
-                                             (list.repeated inner_arity (synthesis.bit @ expected_bit))])]
+                                                                 (list.repeated outer_arity (synthesis.bit @ expected_bit))]))
+                                      inner_application (is synthesis.Term
+                                                            (<| (synthesis.function/apply @)
+                                                                [outer_application
+                                                                 (list.repeated inner_arity (synthesis.bit @ expected_bit))]))]
+                                it (next archive inner_application)]
                                (in (|> it
                                        [{.#None}]
-                                       (of host evaluate $unit)
+                                       (of host evaluate)
                                        (try#each (|>> (as I64)
                                                       (i64#= expected_i64)))
                                        (try.else false))))))
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function/field/variable/count.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function/field/variable/count.lux
index 974851bfd..a370740d7 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function/field/variable/count.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/function/field/variable/count.lux
@@ -63,8 +63,7 @@
                             (function (_ _)
                               (undefined)))
                next (jvm.translate extender complexT.lux)
-               @ [module 0 0]
-               $unit [(-- 0) (-- 0)]]
+               @ [module 0 0]]
 
          arity (of ! each (|>> (n.% arity.maximum) (n.max arity.minimum)) random.nat)
          partial_application (of ! each (n.% arity) random.nat)])
@@ -82,7 +81,7 @@
                         !.i2l
                         (value.boxed type.long))
                    [{.#None}]
-                   (of host evaluate $unit)
+                   (of host evaluate)
                    (try#each (|>> (as Nat) (n#= 0)))
                    (try.else false))))
            (_.coverage [/.value]
@@ -104,7 +103,7 @@
                                             !.i2l
                                             (value.boxed type.long))
                                        [{.#None}]
-                                       (of host evaluate $unit)
+                                       (of host evaluate)
                                        (try#each (|>> (as Nat) (n#= 0)))
                                        (try.else false))))))
                        (try.else false))
@@ -130,7 +129,7 @@
                                             !.i2l
                                             (value.boxed type.long))
                                        [{.#None}]
-                                       (of host evaluate $unit)
+                                       (of host evaluate)
                                        (try#each (|>> (as Nat) (n#= partial_application)))
                                        (try.else false))))))
                        (try.else false))]
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux
index e175d3202..8272618f6 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/host.lux
@@ -28,13 +28,12 @@
   Test
   (<| (_.covering /._)
       (do [! random.monad]
-        [.let [$unit [0 0]]
-         expected (random.upper_cased 1)])
+        [expected (random.upper_cased 1)])
       (all _.and
            (_.coverage [/.host]
              (io.run! (do io.monad
                         [[class_loader host] /.host]
-                        (in (when (of host evaluate $unit [{.#None} (bytecode.string expected)])
+                        (in (when (of host evaluate [{.#None} (bytecode.string expected)])
                               {try.#Success actual}
                               (text#= expected (as Text actual))
                               
@@ -43,7 +42,7 @@
            (_.coverage [/.invalid_value]
              (io.run! (do io.monad
                         [[class_loader host] /.host]
-                        (in (when (of host evaluate $unit [{.#None} bytecode.aconst_null])
+                        (in (when (of host evaluate [{.#None} bytecode.aconst_null])
                               {try.#Success _}
                               false
                               
@@ -52,13 +51,13 @@
            (_.coverage [/.cannot_load]
              (io.run! (do io.monad
                         [[class_loader host] /.host]
-                        (in (when (of host evaluate $unit [{.#None} (all bytecode.composite
-                                                                         bytecode.lconst_0
-                                                                         bytecode.lconst_0
-                                                                         bytecode.ldiv
-                                                                         bytecode.pop2
-                                                                         (bytecode.string expected)
-                                                                         )])
+                        (in (when (of host evaluate [{.#None} (all bytecode.composite
+                                                                   bytecode.lconst_0
+                                                                   bytecode.lconst_0
+                                                                   bytecode.ldiv
+                                                                   bytecode.pop2
+                                                                   (bytecode.string expected)
+                                                                   )])
                               {try.#Success _}
                               false
                               
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/primitive.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/primitive.lux
index 60088f11f..565903706 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/primitive.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/primitive.lux
@@ -31,15 +31,13 @@
         [expected_bit random.bit
          expected_i64 random.i64
          expected_f64 random.frac
-         expected_text (random.lower_cased 1)
-
-         .let [$unit [0 0]]])
+         expected_text (random.lower_cased 1)])
       (`` (all _.and
                (,, (with_template [<constructor> <expected> <type> <=>]
                      [(_.coverage [<constructor>]
                         (io.run! (do io.monad
                                    [[class_loader host] host.host]
-                                   (in (when (of host evaluate $unit [{.#None} (<constructor> <expected>)])
+                                   (in (when (of host evaluate [{.#None} (<constructor> <expected>)])
                                          {try.#Success actual}
                                          (<=> <expected> (as <type> actual))
                                          
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/reference.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/reference.lux
index a8d780b3e..1c039fe6b 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/reference.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/reference.lux
@@ -52,8 +52,7 @@
                             (function (_ _)
                               (undefined)))
                next (//.translate extender complexT.lux)
-               @ [module 0 0]
-               $unit [(-- 0) (-- 0)]]
+               @ [module 0 0]]
 
          before (of ! each (n.% 8) random.nat)
          after (of ! each (n.% 8) random.nat)
@@ -79,7 +78,7 @@
                                                      (list.repeated after (synthesis.i64 @ dummy)))]))]
                          (in (|> it
                                  [{.#None}]
-                                 (of host evaluate $unit)
+                                 (of host evaluate)
                                  (try#each (|>> (as I64)
                                                 (i64#= expected)))
                                  (try.else false))))))
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/value.lux b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/value.lux
index 1190b7eac..b01c2e334 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/value.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/phase/translation/jvm/value.lux
@@ -38,9 +38,7 @@
         [expected_bit random.bit
          expected_i64 random.i64
          expected_f64 random.frac
-         expected_text (random.lower_cased 1)
-
-         .let [$unit [0 0]]])
+         expected_text (random.lower_cased 1)])
       (`` (all _.and
                (_.coverage [/.field]
                  (not (text.empty? /.field)))
@@ -48,12 +46,12 @@
                  (and (,, (with_template [<constructor> <expected> <lux_type> <=> <jvm_type>]
                             [(io.run! (do io.monad
                                         [[class_loader host] host.host]
-                                        (in (when (of host evaluate $unit [{.#None}
-                                                                           (all //.composite
-                                                                                (<constructor> <expected>)
-                                                                                (/.primitive <jvm_type>)
-                                                                                (/.boxed <jvm_type>)
-                                                                                )])
+                                        (in (when (of host evaluate [{.#None}
+                                                                     (all //.composite
+                                                                          (<constructor> <expected>)
+                                                                          (/.primitive <jvm_type>)
+                                                                          (/.boxed <jvm_type>)
+                                                                          )])
                                               {try.#Success actual}
                                               (<=> <expected> (as <lux_type> actual))
                                               
diff --git a/stdlib/source/test/lux/meta/compiler/language/lux/translation.lux b/stdlib/source/test/lux/meta/compiler/language/lux/translation.lux
index 3a29d167a..babc74324 100644
--- a/stdlib/source/test/lux/meta/compiler/language/lux/translation.lux
+++ b/stdlib/source/test/lux/meta/compiler/language/lux/translation.lux
@@ -31,7 +31,7 @@
 (def dummy_host
   (/.Host Any Any)
   (implementation
-   (def (evaluate _ _)
+   (def (evaluate _)
      {try.#Failure ""})
    (def (execute _)
      {try.#Failure ""})
diff --git a/stdlib/source/test/lux/meta/compiler/meta/context.lux b/stdlib/source/test/lux/meta/compiler/meta/context.lux
index f310fc9d0..7229c3804 100644
--- a/stdlib/source/test/lux/meta/compiler/meta/context.lux
+++ b/stdlib/source/test/lux/meta/compiler/meta/context.lux
@@ -34,16 +34,20 @@
 (def .public test
   Test
   (<| (_.covering /._)
-      (_.for [/.Context /.Extension])
+      (_.for [/.Extension
+
+              /.Context
+              /.#host /.#host_module_extension /.#target /.#artifact_extension])
       (do [! random.monad]
         [target (random.lower_cased 1)]
         (all _.and
-             (_.coverage [/.js /.jvm /.lua /.python /.ruby]
+             (_.coverage [/.js /.jvm /.lua /.python /.ruby /.c++]
                (let [contexts (list (/.js target)
                                     (/.jvm target)
                                     (/.lua target)
                                     (/.python target)
-                                    (/.ruby target))
+                                    (/.ruby target)
+                                    (/.c++ target))
                      maximum (list.size contexts)]
                  (`` (and (,, (with_template [<amount> <slot>]
                                 [(|> contexts
diff --git a/stdlib/source/test/lux/meta/compiler/target/jvm.lux b/stdlib/source/test/lux/meta/compiler/target/jvm.lux
index 3abe5e315..7d1033a6a 100644
--- a/stdlib/source/test/lux/meta/compiler/target/jvm.lux
+++ b/stdlib/source/test/lux/meta/compiler/target/jvm.lux
@@ -1753,7 +1753,7 @@
 
 (def .public test
   Test
-  (<| (_.context (%.symbol (symbol .._)))
+  (<| (_.covering .._)
       (all _.and
            (<| (_.context "instruction")
                ..instruction)
diff --git a/stdlib/source/test/lux/world/time/series/average.lux b/stdlib/source/test/lux/world/time/series/average.lux
index d4c6df8e7..fc5843ca6 100644
--- a/stdlib/source/test/lux/world/time/series/average.lux
+++ b/stdlib/source/test/lux/world/time/series/average.lux
@@ -57,7 +57,7 @@
   Test
   (<| (_.covering /._)
       (do [! random.monad]
-        [expected_events (of ! each (|>> (n.% 10) ++) random.nat)
+        [expected_events (of ! each (|>> (n.% 9) (n.+ 2)) random.nat)
          input (series expected_events)
          additional (of ! each (n.% expected_events) random.nat)])
       (all _.and
@@ -102,13 +102,18 @@
                              weighted (/.moving /.weighted
                                                 additional
                                                 input)
-                             .let [(open "//#[0]") (//.equivalence f.equivalence)]]
-                            (in (and (and (well_windowed? input additional exponential)
-                                          (well_windowed? input additional simple)
-                                          (well_windowed? input additional weighted))
-                                     (and (not (//#= exponential simple))
-                                          (not (//#= exponential weighted))
-                                          (not (//#= simple weighted)))
-                                     )))))
+                             .let [(open "//#[0]") (//.equivalence f.equivalence)
+
+                                   all_are_well_windowed!
+                                   (and (well_windowed? input additional exponential)
+                                        (well_windowed? input additional simple)
+                                        (well_windowed? input additional weighted))
+
+                                   all_are_different!
+                                   (and (not (//#= exponential simple))
+                                        (not (//#= exponential weighted))
+                                        (not (//#= simple weighted)))]]
+                            (in (and all_are_well_windowed!
+                                     all_are_different!)))))
                     ))
            )))