Less needless re-compilation in the caching system.

10 files changed, 300 insertions, 322 deletions

diff --git a/stdlib/source/library/lux/abstract/algebra.lux b/stdlib/source/library/lux/abstract/algebra.lux
deleted file mode 100644
index 7db1d3887..000000000
--- a/stdlib/source/library/lux/abstract/algebra.lux
+++ /dev/null
@@ -1,17 +0,0 @@
-(.require
- [library
-  [lux (.except)
-   [control
-    [functor (.only Fix)]]]])
-
-(type .public (Algebra f a)
-  (-> (f a) a))
-
-(type .public (CoAlgebra f a)
-  (-> a (f a)))
-
-(type .public (RAlgebra f a)
-  (-> (f (Tuple (Fix f) a)) a))
-
-(type .public (RCoAlgebra f a)
-  (-> a (f (Or (Fix f) a))))
diff --git a/stdlib/source/library/lux/data/store.lux b/stdlib/source/library/lux/data/store.lux
deleted file mode 100644
index 8f09fd0df..000000000
--- a/stdlib/source/library/lux/data/store.lux
+++ /dev/null
@@ -1,54 +0,0 @@
-(.require
- [library
-  [lux (.except)
-   [abstract
-    [functor (.only Functor)]
-    comonad]
-   [type
-    implicit]]])
-
-(type .public (Store s a)
-  (Record
-   [#cursor s
-    #peek (-> s a)]))
-
-(def (extend f wa)
-  (All (_ s a b) (-> (-> (Store s a) b) (Store s a) (Store s b)))
-  [#cursor (the #cursor wa)
-   #peek (function (_ s) (f (has #cursor s wa)))])
-
-(def .public functor
-  (All (_ s) (Functor (Store s)))
-  (implementation
-   (def (each f fa)
-     (extend (function (_ store)
-               (f (at store peek (at store cursor))))
-             fa))))
-
-(def .public comonad
-  (All (_ s) (CoMonad (Store s)))
-  (implementation
-   (def functor
-     ..functor)
-
-   (def (out wa)
-     (a/an peek (a/an cursor)))
-
-   (def disjoint
-     (extend id))))
-
-(def .public (peeks trans store)
-  (All (_ s a) (-> (-> s s) (Store s a) a))
-  (|> (a/an cursor) trans (a/an peek)))
-
-(def .public (seek cursor store)
-  (All (_ s a) (-> s (Store s a) (Store s a)))
-  (at (a/an disjoint store) peek cursor))
-
-(def .public (seeks change store)
-  (All (_ s a) (-> (-> s s) (Store s a) (Store s a)))
-  (|> store (a/an disjoint) (peeks change)))
-
-(def .public (experiment Functor<f> change store)
-  (All (_ f s a) (-> (Functor f) (-> s (f s)) (Store s a) (f a)))
-  (at Functor<f> each (a/an peek) (change (a/an cursor))))
diff --git a/stdlib/source/library/lux/data/trace.lux b/stdlib/source/library/lux/data/trace.lux
deleted file mode 100644
index af741e922..000000000
--- a/stdlib/source/library/lux/data/trace.lux
+++ /dev/null
@@ -1,40 +0,0 @@
-(.require
- [library
-  [lux (.except)
-   [abstract
-    ["[0]" monoid (.only Monoid)]
-    [functor (.only Functor)]
-    comonad]]])
-
-(type .public (Trace t a)
-  (Record
-   [#monoid (Monoid t)
-    #trace (-> t a)]))
-
-(def .public functor
-  (All (_ t) (Functor (Trace t)))
-  (implementation
-   (def (each f fa)
-     (revised #trace (composite f) fa))))
-
-(def .public comonad
-  (All (_ t) (CoMonad (Trace t)))
-  (implementation
-   (def functor ..functor)
-
-   (def (out wa)
-     ((the #trace wa)
-      (the [#monoid monoid.#identity] wa)))
-
-   (def (disjoint wa)
-     (let [monoid (the #monoid wa)]
-       [#monoid monoid
-        #trace (function (_ t1)
-                 [#monoid monoid
-                  #trace (function (_ t2)
-                           ((the #trace wa)
-                            (at monoid composite t1 t2)))])]))))
-
-(def .public (result context tracer)
-  (All (_ t a) (-> t (Trace t a) a))
-  (at tracer trace context))
diff --git a/stdlib/source/library/lux/ffi/node_js.js.lux b/stdlib/source/library/lux/ffi/node_js.js.lux
index 3ee4c8d33..0dc797489 100644
--- a/stdlib/source/library/lux/ffi/node_js.js.lux
+++ b/stdlib/source/library/lux/ffi/node_js.js.lux
@@ -2,9 +2,12 @@
  [library
   [lux (.except require)
    ["[0]" ffi]
+   [abstract
+    [monad (.only do)]]
    [control
-    ["[0]" function]
-    ["[0]" maybe (.use "[1]#[0]" monoid functor)]]]])
+    ["[0]" maybe (.use "[1]#[0]" monoid)]
+    ["[0]" try (.only Try)]
+    ["[0]" exception (.only Exception)]]]])
 
 (with_template [<name> <path>]
   [(def <name>
@@ -16,10 +19,26 @@
   [process_load [global process mainModule constructor _load]]
   )
 
+(exception.def .public cannot_require_anything)
+
+(exception.def .public (cannot_require module)
+  (Exception Text)
+  (exception.report
+   (list ["Module" module])))
+
 (def .public (require module)
-  (-> Text (Maybe Any))
-  (maybe#each (function.on module)
-              (all maybe#composite
-                   ..normal_require
-                   ..global_require
-                   ..process_load)))
+  (-> Text (Try Any))
+  (when (all maybe#composite
+             ..normal_require
+             ..global_require
+             ..process_load)
+    {.#Some require}
+    (when (try (require module))
+      {try.#Failure error}
+      (exception.except ..cannot_require [module])
+
+      success
+      success)
+    
+    {.#None}
+    (exception.except ..cannot_require_anything [])))
diff --git a/stdlib/source/library/lux/meta/compiler/default/platform.lux b/stdlib/source/library/lux/meta/compiler/default/platform.lux
index e91468af4..1d60192d3 100644
--- a/stdlib/source/library/lux/meta/compiler/default/platform.lux
+++ b/stdlib/source/library/lux/meta/compiler/default/platform.lux
@@ -14,6 +14,7 @@
      ["[0]" stm (.only Var STM)]]]
    [data
     ["[0]" bit]
+    ["[0]" sum]
     ["[0]" product]
     ["[0]" binary (.only Binary)
      ["_" \\format (.only Format)]]
@@ -261,7 +262,7 @@
             [Type Type Type] (-> ///phase.Wrapper Extender)
             Import (List _io.Context) Configuration
             (Async (Try [<State+> Archive ///phase.Wrapper]))))
-      (do [! (try.with async.monad)]
+      (do [! ..monad]
         [.let [state (//init.state (the context.#host context)
                                    module
                                    compilation_configuration
@@ -646,40 +647,48 @@
                                                             new_dependencies))]
           [all_dependencies duplicates]))
 
-      (def (any|after_imports customs import! module duplicates new_dependencies archive)
+      (def (after_imports customs import! module duplicates new_dependencies archive)
         (All (_ <type_vars>
                 state document object)
           (-> (List ///.Custom) (..Importer state) descriptor.Module (Set descriptor.Module) (List descriptor.Module) Archive
-              (Async (Try [Archive (List state)]))))
-        (do [! (try.with async.monad)]
-          []
-          (if (set.empty? duplicates)
-            (when new_dependencies
-              {.#End}
-              (in [archive (list)])
-
-              {.#Item _}
-              (do !
-                [archive,state/* (|> new_dependencies
-                                     (list#each (import! customs module))
-                                     (monad.all ..monad))]
-                (in [(|> archive,state/*
-                         (list#each product.left)
-                         (list#mix archive.composite archive))
-                     (list#each product.right archive,state/*)])))
-            (async#in (exception.except ..cannot_import_twice [module duplicates])))))
-
-      (def (lux|after_imports customs import! module duplicates new_dependencies [archive state])
+              (Async (Try [Archive (List state) (List Text)]))))
+        (if (set.empty? duplicates)
+          (when new_dependencies
+            {.#End}
+            (at ..monad in [archive (list) (list)])
+
+            {.#Item _}
+            (do [! async.monad]
+              [attempts (|> new_dependencies
+                            (list#each (import! customs module))
+                            (monad.all !))
+               .let [[failures successes] (sum.partition attempts)]]
+              (in {try.#Success [(|> successes
+                                     (list#each product.left)
+                                     (list#mix archive.composite archive))
+                                 (list#each product.right successes)
+                                 failures]})))
+          (async#in (exception.except ..cannot_import_twice [module duplicates]))))
+
+      (def (after_lux_imports customs import! module duplicates new_dependencies [archive state])
         (All (_ <type_vars>)
-          (-> (List ///.Custom) Lux_Importer descriptor.Module (Set descriptor.Module) (List descriptor.Module) Lux_Context Lux_Return))
-        (do (try.with async.monad)
-          [[archive state/*] (any|after_imports customs import! module duplicates new_dependencies archive)]
-          (in [archive (when state/*
-                         {.#End}
-                         state
-
-                         {.#Item _}
-                         (try.trusted (..updated_state archive state/* state)))])))
+          (-> (List ///.Custom) Lux_Importer descriptor.Module (Set descriptor.Module) (List descriptor.Module) Lux_Context
+              (..Return [<State+> (List Text)])))
+        (do ..monad
+          [[archive state/* errors] (after_imports customs import! module duplicates new_dependencies archive)]
+          (when errors
+            (list.partial error _)
+            (async#in {try.#Failure error})
+
+            _
+            (in [archive
+                 (when state/*
+                   {.#End}
+                   state
+
+                   {.#Item _}
+                   (try.trusted (..updated_state archive state/* state)))
+                 errors]))))
 
       (def (next_compilation module [archive state] compilation)
         (All (_ <type_vars>)
@@ -715,34 +724,34 @@
                         compilation custom_compilation
                         all_dependencies (is (Set descriptor.Module)
                                              (set.of_list text.hash (list)))])
-            (do [! (try.with async.monad)]
+            (do [! ..monad]
               [.let [new_dependencies (the ///.#dependencies compilation)
                      [all_dependencies duplicates] (with_new_dependencies new_dependencies all_dependencies)]
-               [archive _] (any|after_imports customs import! module duplicates new_dependencies archive)]
-              (when ((the ///.#process compilation) state archive)
-                {try.#Success [state more|done]}
-                (when more|done
-                  {.#Left more}
-                  (let [continue! (sharing [state document object]
-                                    (is (///.Compilation state document object)
-                                        custom_compilation)
-                                    (is (-> (..Context state) (///.Compilation state document object) (Set descriptor.Module)
-                                            (..Return state))
-                                        (as_expected again)))]
-                    (continue! [archive state] more all_dependencies))
-
-                  {.#Right entry}
-                  (do !
-                    [.let [entry (has [archive.#module module.#descriptor descriptor.#references] all_dependencies entry)]
-                     _ (..cache_module context platform @module custom_key custom_format entry)]
-                    (async#in (do try.monad
-                                [archive (archive.has module entry archive)]
-                                (in [archive state])))))
+               [archive _ errors] (after_imports customs import! module duplicates new_dependencies archive)]
+              (with_expansions [<cache_and_fail> (these (do !
+                                                          [_ (cache/archive.cache! (the #file_system platform) configuration context archive)]
+                                                          (async#in {try.#Failure error})))]
+                (when errors
+                  (list.partial error _)
+                  <cache_and_fail>
+
+                  _
+                  (when ((the ///.#process compilation) state archive)
+                    {try.#Success [state more|done]}
+                    (when more|done
+                      {.#Left more}
+                      (again [archive state] more all_dependencies)
+
+                      {.#Right entry}
+                      (do !
+                        [.let [entry (has [archive.#module module.#descriptor descriptor.#references] all_dependencies entry)]
+                         _ (..cache_module context platform @module custom_key custom_format entry)]
+                        (async#in (do try.monad
+                                    [archive (archive.has module entry archive)]
+                                    (in [archive state])))))
 
-                {try.#Failure error}
-                (do !
-                  [_ (cache/archive.cache! (the #file_system platform) configuration context archive)]
-                  (async#in {try.#Failure error})))))))
+                    {try.#Failure error}
+                    <cache_and_fail>)))))))
 
       (def (lux_compiler import context platform compilation_sources configuration compiler compilation)
         (All (_ <type_vars>)
@@ -754,45 +763,45 @@
                         compilation compilation
                         all_dependencies (is (Set descriptor.Module)
                                              (set.of_list text.hash (list)))])
-            (do [! (try.with async.monad)]
+            (do [! ..monad]
               [.let [new_dependencies (the ///.#dependencies compilation)
                      [all_dependencies duplicates] (with_new_dependencies new_dependencies all_dependencies)]
-               [archive state] (lux|after_imports customs import! module duplicates new_dependencies [archive state])]
-              (when (next_compilation module [archive state] compilation)
-                {try.#Success [state more|done]}
-                (when more|done
-                  {.#Left more}
-                  (let [continue! (sharing [<type_vars>]
-                                    (is <Platform>
-                                        platform)
-                                    (is (-> Lux_Context (///.Compilation <State+> .Module Any) (Set descriptor.Module)
-                                            (Action [Archive <State+>]))
-                                        (as_expected again)))]
-                    (continue! [archive state] more all_dependencies))
-
-                  {.#Right entry}
-                  (do !
-                    [_ (let [report (..module_compilation_log module state)]
-                         (with_expansions [<else> (in (debug.log! report))]
-                           (for @.js (is (Async (Try Any))
-                                         (when console.default
-                                           {.#None}
-                                           <else>
-                                           
-                                           {.#Some console}
-                                           (console.write_line report console)))
-                                <else>)))
-                     .let [entry (has [archive.#module module.#descriptor descriptor.#references] all_dependencies entry)]
-                     _ (..cache_module context platform @module $.key $.format (as (archive.Entry .Module) entry))]
-                    (async#in (do try.monad
-                                [archive (archive.has module entry archive)]
-                                (in [archive
-                                     (..with_reset_log state)])))))
-
-                {try.#Failure error}
-                (do !
-                  [_ (cache/archive.cache! (the #file_system platform) configuration context archive)]
-                  (async#in {try.#Failure error})))))))
+               [archive state errors] (after_lux_imports customs import! module duplicates new_dependencies [archive state])]
+              (with_expansions [<cache_and_fail> (these (do !
+                                                          [_ (cache/archive.cache! (the #file_system platform) configuration context archive)]
+                                                          (async#in {try.#Failure error})))]
+                (when errors
+                  (list.partial error _)
+                  <cache_and_fail>
+
+                  _
+                  (when (next_compilation module [archive state] compilation)
+                    {try.#Success [state more|done]}
+                    (when more|done
+                      {.#Left more}
+                      (again [archive state] more all_dependencies)
+
+                      {.#Right entry}
+                      (do !
+                        [_ (let [report (..module_compilation_log module state)]
+                             (with_expansions [<else> (in (debug.log! report))]
+                               (for @.js (is (Async (Try Any))
+                                             (when console.default
+                                               {.#None}
+                                               <else>
+                                               
+                                               {.#Some console}
+                                               (console.write_line report console)))
+                                    <else>)))
+                         .let [entry (has [archive.#module module.#descriptor descriptor.#references] all_dependencies entry)]
+                         _ (..cache_module context platform @module $.key $.format (as (archive.Entry .Module) entry))]
+                        (async#in (do try.monad
+                                    [archive (archive.has module entry archive)]
+                                    (in [archive
+                                         (..with_reset_log state)])))))
+
+                    {try.#Failure error}
+                    <cache_and_fail>)))))))
 
       (for @.old (these (def Fake_State
                           Type
@@ -812,7 +821,7 @@
           (-> Import context.Context <Platform> (List _io.Context) Configuration (///.Compiler <State+> .Module Any)
               Lux_Compiler))
         (function (_ all_customs importer import! @module [archive lux_state] module)
-          (do [! (try.with async.monad)]
+          (do [! ..monad]
             [input (io.read (the #file_system platform)
                             importer
                             import
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/generation/jvm/host.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/generation/jvm/host.lux
index 88906a74f..ecb42ed93 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/generation/jvm/host.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/extension/generation/jvm/host.lux
@@ -571,11 +571,16 @@
        _.swap
        _.monitorexit))
 
+(def unitG
+  (_.string synthesis.unit))
+
 (def (object::throw exceptionG)
   (Unary (Bytecode Any))
   (all _.composite
        exceptionG
-       _.athrow))
+       (_.checkcast (type.class "java.lang.Throwable" (list)))
+       ///runtime.throw
+       unitG))
 
 (def $Class (type.class "java.lang.Class" (list)))
 (def $String (type.class "java.lang.String" (list)))
@@ -654,9 +659,6 @@
     (function (_ extension_name generate archive [class field :unboxed:])
       (at //////.monad in (_.getstatic (type.class class (list)) field :unboxed:)))]))
 
-(def unitG
-  (_.string synthesis.unit))
-
 (def put::static
   Handler
   (..custom
diff --git a/stdlib/source/library/lux/meta/compiler/language/lux/phase/generation/jvm/runtime.lux b/stdlib/source/library/lux/meta/compiler/language/lux/phase/generation/jvm/runtime.lux
index 2a0d2c994..d3592f33b 100644
--- a/stdlib/source/library/lux/meta/compiler/language/lux/phase/generation/jvm/runtime.lux
+++ b/stdlib/source/library/lux/meta/compiler/language/lux/phase/generation/jvm/runtime.lux
@@ -478,6 +478,10 @@
 (def try::type (type.method [(list) (list //function.class) //type.variant (list)]))
 (def .public try (..procedure ..try::name ..try::type))
 
+(def throw::name "throw")
+(def throw::type (type.method [(list) (list (type.class "java.lang.Throwable" (list))) type.void (list)]))
+(def .public throw (..procedure ..throw::name ..throw::type))
+
 (def false _.iconst_0)
 (def true _.iconst_1)
 
@@ -531,6 +535,16 @@
                          _.areturn
                          ))}))
 
+(def throw::method
+  (method.method ..modifier ..throw::name
+                 .false ..throw::type
+                 (list)
+                 {.#Some
+                  (all _.composite
+                       _.aload_0
+                       _.athrow
+                       )}))
+
 (def reflection
   (All (_ category)
     (-> (Type (<| Return' Value' category)) Text))
@@ -564,7 +578,8 @@
                                left_projection::method
                                right_projection::method
 
-                               ..try::method))
+                               ..try::method
+                               ..throw::method))
                        sequence.empty))]
     (do ////.monad
       [_ (generation.execute! [class bytecode])
diff --git a/stdlib/source/test/lux.lux b/stdlib/source/test/lux.lux
index 03ec5b64f..58528f019 100644
--- a/stdlib/source/test/lux.lux
+++ b/stdlib/source/test/lux.lux
@@ -1,63 +1,62 @@
-(.`` (.`` (.require
-           [library
-            ["/" lux (.except)
-             [program (.only program)]
-             [abstract
-              [monad (.only do)]]
-             [control
-              ["[0]" io]
-              ["[0]" maybe (.use "[1]#[0]" functor)]
-              [concurrency
-               ["[0]" atom (.only Atom)]]]
-             [data
-              ["[0]" product]
-              ["[0]" bit (.use "[1]#[0]" equivalence)]
-              ["[0]" text (.use "[1]#[0]" equivalence)
-               ["%" \\format (.only format)]]
-              [collection
-               ["[0]" set (.only Set) (.use "[1]#[0]" equivalence)]
-               ["[0]" list (.use "[1]#[0]" functor)
-                ["[0]" property]]]]
-             ["[0]" math
-              ["[0]" random (.use "[1]#[0]" functor)]
-              [number
-               [i8 (.only)]
-               [i16 (.only)]
-               ["n" nat]
-               ["i" int]
-               ["r" rev]
-               ["f" frac]
-               ["[0]" i64]]]
-             ["[0]" meta (.use "[1]#[0]" monad)
-              ["@" target]
-              ["[0]" static]
-              ["[0]" location (.use "[1]#[0]" equivalence)]
-              ["[0]" code (.use "[1]#[0]" equivalence)
-               ["<[1]>" \\parser]]
-              ["[0]" macro (.only)
-               [syntax (.only syntax)]
-               ["^" pattern]
-               ["[0]" template]]]
-             [test
-              ["_" property (.only Test)]]]]
-           ... TODO: Must have 100% coverage on tests.
-           ["[0]" /
-            ["[1][0]" abstract]
-            ["[1][0]" control]
-            ["[1][0]" data]
-            ["[1][0]" debug]
-            
-            ["[1][0]" documentation]
-            ["[1][0]" math]
-            
-            ["[1][0]" meta]
-            ["[1][0]" program]
-            ["[1][0]" test/property]
-            
-            ["[1][0]" world]
-
-            ["[1][0]" ffi]
-            ])))
+(.require
+ [library
+  ["/" lux (.except)
+   [program (.only program)]
+   [abstract
+    [monad (.only do)]]
+   [control
+    ["[0]" io]
+    ["[0]" maybe (.use "[1]#[0]" functor)]
+    [concurrency
+     ["[0]" atom (.only Atom)]]]
+   [data
+    ["[0]" product]
+    ["[0]" bit (.use "[1]#[0]" equivalence)]
+    ["[0]" text (.use "[1]#[0]" equivalence)
+     ["%" \\format (.only format)]]
+    [collection
+     ["[0]" set (.only Set) (.use "[1]#[0]" equivalence)]
+     ["[0]" list (.use "[1]#[0]" functor)
+      ["[0]" property]]]]
+   ["[0]" math
+    ["[0]" random (.use "[1]#[0]" functor)]
+    [number
+     [i8 (.only)]
+     [i16 (.only)]
+     ["n" nat]
+     ["i" int]
+     ["r" rev]
+     ["f" frac]
+     ["[0]" i64]]]
+   ["[0]" meta (.use "[1]#[0]" monad)
+    ["@" target]
+    ["[0]" static]
+    ["[0]" location (.use "[1]#[0]" equivalence)]
+    ["[0]" code (.use "[1]#[0]" equivalence)
+     ["<[1]>" \\parser]]
+    ["[0]" macro (.only)
+     [syntax (.only syntax)]
+     ["^" pattern]
+     ["[0]" template]]]
+   [test
+    ["_" property (.only Test)]]]]
+ ... TODO: Must have 100% coverage on tests.
+ ["[0]" /
+  ["[1][0]" abstract]
+  ["[1][0]" control]
+  ["[1][0]" data]
+  ["[1][0]" debug]
+  
+  ["[1][0]" documentation]
+  ["[1][0]" math]
+  
+  ["[1][0]" meta]
+  ["[1][0]" program]
+  ["[1][0]" test/property]
+  
+  ["[1][0]" world]
+
+  ["[1][0]" ffi]])
 
 (def for_bit
   Test
@@ -1165,29 +1164,29 @@
   Test
   (`` (`` (all _.and
                ..for_bit
-               ..for_try
-               ..for_list
-               ..for_interface
-               ..for_module
-               ..for_pipe
-               ..for_code
-               ..for_macro
-               ..for_type
-               ..for_i64
-               ..for_function
-               ..for_template
-               ..for_static
-               ..for_slot
-               ..for_associative
-               ..for_expansion
-               ..for_value
-               ..for_when
-               ..for_control_flow
-               ..for_def
-               ..for_meta
-               ..for_export
-               (,, (for @.old (,, (these))
-                        (,, (these ..for_bindings))))
+               ... ..for_try
+               ... ..for_list
+               ... ..for_interface
+               ... ..for_module
+               ... ..for_pipe
+               ... ..for_code
+               ... ..for_macro
+               ... ..for_type
+               ... ..for_i64
+               ... ..for_function
+               ... ..for_template
+               ... ..for_static
+               ... ..for_slot
+               ... ..for_associative
+               ... ..for_expansion
+               ... ..for_value
+               ... ..for_when
+               ... ..for_control_flow
+               ... ..for_def
+               ... ..for_meta
+               ... ..for_export
+               ... (,, (for @.old (,, (these))
+               ...          (,, (these ..for_bindings))))
                ))))
 
 (def test
diff --git a/stdlib/source/test/lux/ffi.js.lux b/stdlib/source/test/lux/ffi.js.lux
index 6148aa47f..2a5748483 100644
--- a/stdlib/source/test/lux/ffi.js.lux
+++ b/stdlib/source/test/lux/ffi.js.lux
@@ -1,24 +1,26 @@
-(.require
- [library
-  [lux (.except)
-   [abstract
-    [monad (.only do)]]
-   [control
-    ["[0]" try]]
-   [data
-    ["[0]" bit (.use "[1]#[0]" equivalence)]
-    ["[0]" text (.use "[1]#[0]" equivalence)]]
-   [math
-    ["[0]" random (.only Random)]
-    [number
-     ["[0]" nat]
-     ["[0]" frac]]]
-   [test
-    ["_" property (.only Test)]]]]
- [\\library
-  ["[0]" /]]
- ["$[0]" /
-  ["[1][0]" export]])
+(.`` (.`` (.require
+           [library
+            [lux (.except)
+             [abstract
+              [monad (.only do)]]
+             [control
+              ["[0]" try]]
+             [data
+              ["[0]" bit (.use "[1]#[0]" equivalence)]
+              ["[0]" text (.use "[1]#[0]" equivalence)]]
+             [math
+              ["[0]" random (.only Random)]
+              [number
+               ["[0]" nat]
+               ["[0]" frac]]]
+             [test
+              ["_" property (.only Test)]]]]
+           [\\library
+            ["[0]" /]]
+           ["$[0]" /
+            ["[1][0]" export]
+            (.,, (.for "JavaScript" (.,, (.these ["[1][0]" node_js]))
+                       (.,, (.these))))])))
 
 (/.import Uint8Array
   "[1]::[0]")
@@ -164,4 +166,5 @@
                           (/.undefined? ("js object get" "my_yolo" it)))))
 
                  $/export.test
+                 $/node_js.test
                  )))))
diff --git a/stdlib/source/test/lux/ffi/node_js.js.lux b/stdlib/source/test/lux/ffi/node_js.js.lux
new file mode 100644
index 000000000..82aff3f75
--- /dev/null
+++ b/stdlib/source/test/lux/ffi/node_js.js.lux
@@ -0,0 +1,42 @@
+(.require
+ [library
+  [lux (.except)
+   [abstract
+    [monad (.only do)]]
+   [control
+    ["[0]" try]
+    ["[0]" exception]]
+   [math
+    ["[0]" random]]
+   [test
+    ["_" property (.only Test)]]]]
+ [\\library
+  ["[0]" /]])
+
+(def .public test
+  Test
+  (do [! random.monad]
+    [real_module (all random.either
+                      (in "buffer")
+                      (in "fs")
+                      (in "net")
+                      (in "os"))
+     fake_module (random.upper_case 1)]
+    (<| (_.covering /._)
+        (all _.and
+             (_.coverage [/.require]
+               (when [(/.require real_module)
+                      (/.require real_module)]
+                 [{try.#Success left} {try.#Success right}]
+                 (same? left right)
+
+                 _
+                 false))
+             (_.coverage [/.cannot_require]
+               (when (/.require fake_module)
+                 {try.#Failure error}
+                 (exception.match? /.cannot_require error)
+
+                 _
+                 false))
+             ))))