Merge branch 'master' into haskell-assignment

HLint.hs

@@ -17,8 +17,8 @@ error "Avoid return" =
     return ==> pure
     where note = "return is obsolete as of GHC 7.10"
 
-error "use extract" = termAnnotation . unTerm ==> extract
+error "use termAnnotation" = termFAnnotation . unTerm ==> termAnnotation
-error "use unwrap" = termOut . unTerm ==> unwrap
+error "use termOut" = termFOut . unTerm ==> termOut
 
 error "avoid head" = head
   where note = "head is partial; consider using Data.Maybe.listToMaybe"
@@ -31,3 +31,5 @@ error "avoid init" = init
 
 error "avoid last" = last
   where note = "last is partial; consider pattern-matching"
+
+error "use maybeM" = maybe a pure ==> maybeM a

semantic.cabal

@@ -40,7 +40,6 @@ library
                      , Control.Abstract.Context
                      , Control.Abstract.Environment
                      , Control.Abstract.Evaluator
-                     , Control.Abstract.Exports
                      , Control.Abstract.Heap
                      , Control.Abstract.Hole
                      , Control.Abstract.Matching

src/Analysis/Abstract/Caching.hs

@@ -62,7 +62,7 @@ cachingTerms :: ( Cacheable term address (Cell address) value
                 , Member (Reader (Cache term address (Cell address) value)) effects
                 , Member (Reader (Live address)) effects
                 , Member (State (Cache term address (Cell address) value)) effects
-                , Member (State (Environment address)) effects
+                , Member (Env address) effects
                 , Member (State (Heap address (Cell address) value)) effects
                 )
              => SubtermAlgebra (Base term) term (TermEvaluator term address value effects (ValueRef value))
@@ -82,11 +82,10 @@ convergingModules :: ( AbstractValue address value effects
                      , Member Fresh effects
                      , Member NonDet effects
                      , Member (Reader (Cache term address (Cell address) value)) effects
-                     , Member (Reader (Environment address)) effects
                      , Member (Reader (Live address)) effects
                      , Member (Resumable (EnvironmentError address)) effects
                      , Member (State (Cache term address (Cell address) value)) effects
-                     , Member (State (Environment address)) effects
+                     , Member (Env address) effects
                      , Member (State (Heap address (Cell address) value)) effects
                      )
                   => SubtermAlgebra Module term (TermEvaluator term address value effects value)
@@ -94,8 +93,7 @@ convergingModules :: ( AbstractValue address value effects
 convergingModules recur m = do
   c <- getConfiguration (subterm (moduleBody m))
   -- Convergence here is predicated upon an Eq instance, not α-equivalence
-  cache <- converge lowerBound (\ prevCache -> isolateCache $ do
+  cache <- converge lowerBound (\ prevCache -> isolateCache $ raiseHandler locally $ do
-    TermEvaluator (putEnv  (configurationEnvironment c))
     TermEvaluator (putHeap (configurationHeap        c))
     -- We need to reset fresh generation so that this invocation converges.
     resetFresh 0 $

src/Analysis/Abstract/Evaluating.hs

@@ -5,14 +5,13 @@ module Analysis.Abstract.Evaluating
 ) where
 
 import Control.Abstract
+import Control.Monad.Effect.Fail
 import Data.Semilattice.Lower
 
 -- | An analysis evaluating @term@s to @value@s with a list of @effects@ using 'Evaluatable', and producing incremental results of type @a@.
 data EvaluatingState address value = EvaluatingState
-  { environment :: Environment address
+  { heap        :: Heap address (Cell address) value
-  , heap        :: Heap address (Cell address) value
   , modules     :: ModuleTable (Maybe (Environment address, value))
-  , exports     :: Exports address
   }
 
 deriving instance (Eq (Cell address value), Eq address, Eq value) => Eq (EvaluatingState address value)
@@ -23,19 +22,13 @@ deriving instance (Show (Cell address value), Show address, Show value) => Show
 evaluating :: Evaluator address value
                 (  Fail
                 ': Fresh
-                ': Reader (Environment address)
-                ': State (Environment address)
                 ': State (Heap address (Cell address) value)
                 ': State (ModuleTable (Maybe (Environment address, value)))
-                ': State (Exports address)
                 ': effects) result
            -> Evaluator address value effects (Either String result, EvaluatingState address value)
 evaluating
-  = fmap (\ ((((result, env), heap), modules), exports) -> (result, EvaluatingState env heap modules exports))
+  = fmap (\ ((result, heap), modules) -> (result, EvaluatingState heap modules))
-  . runState lowerBound -- State (Exports address)
   . runState lowerBound -- State (ModuleTable (Maybe (Environment address, value)))
   . runState lowerBound -- State (Heap address (Cell address) value)
-  . runState lowerBound -- State (Environment address)
-  . runReader lowerBound -- Reader (Environment address)
   . runFresh 0
   . runFail

src/Analysis/Abstract/Graph.hs

@@ -52,9 +52,8 @@ style = (defaultStyle (byteString . vertexName))
 
 -- | Add vertices to the graph for evaluated identifiers.
 graphingTerms :: ( Element Syntax.Identifier syntax
-                 , Member (Reader (Environment (Hole (Located address)))) effects
                  , Member (Reader ModuleInfo) effects
-                 , Member (State (Environment (Hole (Located address)))) effects
+                 , Member (Env (Hole (Located address))) effects
                  , Member (State (Graph Vertex)) effects
                  , term ~ Term (Sum syntax) ann
                  )
@@ -121,8 +120,7 @@ moduleInclusion v = do
   appendGraph (vertex (moduleVertex m) `connect` vertex v)
 
 -- | Add an edge from the passed variable name to the module it originated within.
-variableDefinition :: ( Member (Reader (Environment (Hole (Located address)))) effects
+variableDefinition :: ( Member (Env (Hole (Located address))) effects
-                      , Member (State (Environment (Hole (Located address)))) effects
                       , Member (State (Graph Vertex)) effects
                       )
                    => Name

src/Analysis/Abstract/Tracing.hs

@@ -14,7 +14,7 @@ import Prologue
 --   Instantiating @trace@ to @[]@ yields a linear trace analysis, while @Set@ yields a reachable state analysis.
 tracingTerms :: ( Corecursive term
                 , Member (Reader (Live address)) effects
-                , Member (State (Environment address)) effects
+                , Member (Env address) effects
                 , Member (State (Heap address (Cell address) value)) effects
                 , Member (Writer (trace (Configuration term address (Cell address) value))) effects
                 , Reducer (Configuration term address (Cell address) value) (trace (Configuration term address (Cell address) value))

src/Control/Abstract.hs

@@ -5,9 +5,8 @@ module Control.Abstract
 import Control.Abstract.Addressable as X
 import Control.Abstract.Configuration as X
 import Control.Abstract.Context as X
-import Control.Abstract.Environment as X
+import Control.Abstract.Environment as X hiding (Lookup)
 import Control.Abstract.Evaluator as X
-import Control.Abstract.Exports as X
 import Control.Abstract.Heap as X
 import Control.Abstract.Hole as X
 import Control.Abstract.Modules as X

src/Control/Abstract/Configuration.hs

@@ -12,5 +12,5 @@ import Control.Abstract.TermEvaluator
 import Data.Abstract.Configuration
 
 -- | Get the current 'Configuration' with a passed-in term.
-getConfiguration :: (Member (Reader (Live address)) effects, Member (State (Environment address)) effects, Member (State (Heap address (Cell address) value)) effects) => term -> TermEvaluator term address value effects (Configuration term address (Cell address) value)
+getConfiguration :: (Member (Reader (Live address)) effects, Member (Env address) effects, Member (State (Heap address (Cell address) value)) effects) => term -> TermEvaluator term address value effects (Configuration term address (Cell address) value)
 getConfiguration term = Configuration term <$> TermEvaluator askRoots <*> TermEvaluator getEnv <*> TermEvaluator getHeap

src/Control/Abstract/Environment.hs

@@ -1,14 +1,16 @@
-{-# LANGUAGE GADTs, RankNTypes, TypeOperators #-}
+{-# LANGUAGE GADTs, LambdaCase, RankNTypes, ScopedTypeVariables, TypeOperators #-}
 module Control.Abstract.Environment
 ( Environment
+, Exports
 , getEnv
-, putEnv
+, export
-, withEnv
-, withDefaultEnvironment
 , lookupEnv
 , bind
 , bindAll
 , locally
+, close
+, Env(..)
+, runEnv
 , EnvironmentError(..)
 , freeVariableError
 , runEnvironmentError
@@ -16,54 +18,78 @@ module Control.Abstract.Environment
 ) where
 
 import Control.Abstract.Evaluator
-import Data.Abstract.Environment as Env
+import Data.Abstract.Environment (Environment)
+import qualified Data.Abstract.Environment as Env
+import Data.Abstract.Exports as Exports
 import Data.Abstract.Name
+import Data.Semilattice.Lower
 import Prologue
 
 -- | Retrieve the environment.
-getEnv :: Member (State (Environment address)) effects => Evaluator address value effects (Environment address)
+getEnv :: Member (Env address) effects => Evaluator address value effects (Environment address)
-getEnv = get
+getEnv = send GetEnv
 
--- | Set the environment.
+-- | Add an export to the global export state.
-putEnv :: Member (State (Environment address)) effects => Environment address -> Evaluator address value effects ()
+export :: Member (Env address) effects => Name -> Name -> Maybe address -> Evaluator address value effects ()
-putEnv = put
+export name alias addr = send (Export name alias addr)
 
--- | Update the global environment.
-modifyEnv :: Member (State (Environment address)) effects => (Environment address -> Environment address) -> Evaluator address value effects ()
-modifyEnv = modify'
-
--- | Sets the environment for the lifetime of the given action.
-withEnv :: Member (State (Environment address)) effects => Environment address -> Evaluator address value effects a -> Evaluator address value effects a
-withEnv = localState . const
-
-
--- | Retrieve the default environment.
-defaultEnvironment :: Member (Reader (Environment address)) effects => Evaluator address value effects (Environment address)
-defaultEnvironment = ask
-
--- | Set the default environment for the lifetime of an action.
---   Usually only invoked in a top-level evaluation function.
-withDefaultEnvironment :: Member (Reader (Environment address)) effects => Environment address -> Evaluator address value effects a -> Evaluator address value effects a
-withDefaultEnvironment e = local (const e)
 
 -- | Look a 'Name' up in the current environment, trying the default environment if no value is found.
-lookupEnv :: (Member (Reader (Environment address)) effects, Member (State (Environment address)) effects) => Name -> Evaluator address value effects (Maybe address)
+lookupEnv :: Member (Env address) effects => Name -> Evaluator address value effects (Maybe address)
-lookupEnv name = (<|>) <$> (Env.lookup name <$> getEnv) <*> (Env.lookup name <$> defaultEnvironment)
+lookupEnv name = send (Lookup name)
 
--- | Bind a 'Name' to an 'Address' in the current scope.
+-- | Bind a 'Name' to an address in the current scope.
-bind :: Member (State (Environment address)) effects => Name -> address -> Evaluator address value effects ()
+bind :: Member (Env address) effects => Name -> address -> Evaluator address value effects ()
-bind name = modifyEnv . Env.insert name
+bind name addr = send (Bind name addr)
 
 -- | Bind all of the names from an 'Environment' in the current scope.
-bindAll :: Member (State (Environment address)) effects => Environment address -> Evaluator address value effects ()
+bindAll :: Member (Env address) effects => Environment address -> Evaluator address value effects ()
-bindAll = foldr ((>>) . uncurry bind) (pure ()) . pairs
+bindAll = foldr ((>>) . uncurry bind) (pure ()) . Env.pairs
 
--- | Run an action in a new local environment.
+-- | Run an action in a new local scope.
-locally :: Member (State (Environment address)) effects => Evaluator address value effects a -> Evaluator address value effects a
+locally :: forall address value effects a . Member (Env address) effects => Evaluator address value effects a -> Evaluator address value effects a
 locally a = do
-  modifyEnv Env.push
+  send (Push @address)
   a' <- a
-  a' <$ modifyEnv Env.pop
+  a' <$ send (Pop @address)
+
+close :: Member (Env address) effects => Set Name -> Evaluator address value effects (Environment address)
+close = send . Close
+
+data Env address return where
+  Lookup :: Name            -> Env address (Maybe address)
+  Bind   :: Name -> address -> Env address ()
+  Close  :: Set Name        -> Env address (Environment address)
+  Push   ::                    Env address ()
+  Pop    ::                    Env address ()
+  GetEnv ::                    Env address (Environment address)
+  Export :: Name -> Name -> Maybe address -> Env address ()
+
+handleEnv :: forall address effects value result
+          .  ( Member (State (Environment address)) effects
+             , Member (State (Exports address)) effects
+             )
+          => Env address result
+          -> Evaluator address value effects result
+handleEnv = \case
+  Lookup name -> Env.lookup name <$> get
+  Bind name addr -> modify (Env.insert name addr)
+  Close names -> Env.intersect names <$> get
+  Push -> modify (Env.push @address)
+  Pop -> modify (Env.pop @address)
+  GetEnv -> get
+  Export name alias addr -> modify (Exports.insert name alias addr)
+
+runEnv :: Environment address
+       -> Evaluator address value (Env address ': effects) a
+       -> Evaluator address value effects (a, Environment address)
+runEnv initial = fmap (uncurry filterEnv . first (fmap Env.head)) . runState lowerBound . runState (Env.push initial) . reinterpret2 handleEnv
+  where -- TODO: If the set of exports is empty because no exports have been
+        -- defined, do we export all terms, or no terms? This behavior varies across
+        -- languages. We need better semantics rather than doing it ad-hoc.
+        filterEnv (a, env) ports
+          | Exports.null ports = (a, env)
+          | otherwise          = (a, Exports.toEnvironment ports `Env.mergeEnvs` Env.overwrite (Exports.aliases ports) env)
 
 
 -- | Errors involving the environment.

src/Control/Abstract/Exports.hs

@@ -1,32 +0,0 @@
-module Control.Abstract.Exports
-( Exports
-, getExports
-, putExports
-, modifyExports
-, addExport
-, withExports
-) where
-
-import Control.Abstract.Evaluator
-import Data.Abstract.Exports
-import Data.Abstract.Name
-
--- | Get the global export state.
-getExports :: Member (State (Exports address)) effects => Evaluator address value effects (Exports address)
-getExports = get
-
--- | Set the global export state.
-putExports :: Member (State (Exports address)) effects => Exports address -> Evaluator address value effects ()
-putExports = put
-
--- | Update the global export state.
-modifyExports :: Member (State (Exports address)) effects => (Exports address -> Exports address) -> Evaluator address value effects ()
-modifyExports = modify'
-
--- | Add an export to the global export state.
-addExport :: Member (State (Exports address)) effects => Name -> Name -> Maybe address -> Evaluator address value effects ()
-addExport name alias = modifyExports . insert name alias
-
--- | Sets the global export state for the lifetime of the given action.
-withExports :: Member (State (Exports address)) effects => Exports address -> Evaluator address value effects a -> Evaluator address value effects a
-withExports = localState . const

src/Control/Abstract/Heap.hs

@@ -62,17 +62,15 @@ assign address = modifyHeap . heapInsert address
 
 -- | Look up or allocate an address for a 'Name'.
 lookupOrAlloc :: ( Member (Allocator address value) effects
-                 , Member (Reader (Environment address)) effects
+                 , Member (Env address) effects
-                 , Member (State (Environment address)) effects
                  )
               => Name
               -> Evaluator address value effects address
-lookupOrAlloc name = lookupEnv name >>= maybe (alloc name) pure
+lookupOrAlloc name = lookupEnv name >>= maybeM (alloc name)
 
 
 letrec :: ( Member (Allocator address value) effects
-          , Member (Reader (Environment address)) effects
+          , Member (Env address) effects
-          , Member (State (Environment address)) effects
           , Member (State (Heap address (Cell address) value)) effects
           , Ord address
           , Reducer value (Cell address value)
@@ -88,8 +86,7 @@ letrec name body = do
 
 -- Lookup/alloc a name passing the address to a body evaluated in a new local environment.
 letrec' :: ( Member (Allocator address value) effects
-           , Member (Reader (Environment address)) effects
+           , Member (Env address) effects
-           , Member (State (Environment address)) effects
            )
         => Name
         -> (address -> Evaluator address value effects value)
@@ -102,9 +99,8 @@ letrec' name body = do
 
 -- | Look up and dereference the given 'Name', throwing an exception for free variables.
 variable :: ( Member (Allocator address value) effects
-            , Member (Reader (Environment address)) effects
+            , Member (Env address) effects
             , Member (Resumable (EnvironmentError address)) effects
-            , Member (State (Environment address)) effects
             )
          => Name
          -> Evaluator address value effects value

src/Control/Abstract/Modules.hs

@@ -23,6 +23,7 @@ import Data.Abstract.Environment
 import Data.Abstract.Module
 import Data.Abstract.ModuleTable as ModuleTable
 import Data.Language
+import Data.Tuple (swap)
 import Prologue
 
 -- | Retrieve an evaluated module, if any. The outer 'Maybe' indicates whether we’ve begun loading the module or not, while the inner 'Maybe' indicates whether we’ve completed loading it or not. Thus, @Nothing@ means we’ve never tried to load it, @Just Nothing@ means we’ve started but haven’t yet finished loading it, and @Just (Just (env, value))@ indicates the result of a completed load.
@@ -47,11 +48,11 @@ require path = lookupModule path >>= maybeM (load path)
 --
 -- Always loads/evaluates.
 load :: Member (Modules address value) effects => ModulePath -> Evaluator address value effects (Maybe (Environment address, value))
-load = send . Load
+load path = fmap swap <$> send (Load path)
 
 
 data Modules address value return where
-  Load    :: ModulePath -> Modules address value (Maybe (Environment address, value))
+  Load    :: ModulePath -> Modules address value (Maybe (value, Environment address))
   Lookup  :: ModulePath -> Modules address value (Maybe (Maybe (Environment address, value)))
   Resolve :: [FilePath] -> Modules address value (Maybe ModulePath)
   List    :: FilePath   -> Modules address value [ModulePath]
@@ -64,7 +65,7 @@ runModules :: forall term address value effects a
               , Member (State (ModuleTable (Maybe (Environment address, value)))) effects
               , Member Trace effects
               )
-           => (Module term -> Evaluator address value (Modules address value ': effects) (Environment address, value))
+           => (Module term -> Evaluator address value (Modules address value ': effects) (value, Environment address))
            -> Evaluator address value (Modules address value ': effects) a
            -> Evaluator address value (Reader (ModuleTable [Module term]) ': effects) a
 runModules evaluateModule = go
@@ -92,19 +93,19 @@ runModules evaluateModule = go
 getModuleTable :: Member (State (ModuleTable (Maybe (Environment address, value)))) effects => Evaluator address value effects (ModuleTable (Maybe (Environment address, value)))
 getModuleTable = get
 
-cacheModule :: Member (State (ModuleTable (Maybe (Environment address, value)))) effects => ModulePath -> Maybe (Environment address, value) -> Evaluator address value effects (Maybe (Environment address, value))
+cacheModule :: Member (State (ModuleTable (Maybe (Environment address, value)))) effects => ModulePath -> Maybe (value, Environment address) -> Evaluator address value effects (Maybe (value, Environment address))
-cacheModule path result = modify' (ModuleTable.insert path result) $> result
+cacheModule path result = modify' (ModuleTable.insert path (swap <$> result)) $> result
 
 askModuleTable :: Member (Reader (ModuleTable [Module term])) effects => Evaluator address value effects (ModuleTable [Module term])
 askModuleTable = ask
 
 
-newtype Merging m address value = Merging { runMerging :: m (Maybe (Environment address, value)) }
+newtype Merging m address value = Merging { runMerging :: m (Maybe (value, Environment address)) }
 
 instance Applicative m => Semigroup (Merging m address value) where
   Merging a <> Merging b = Merging (merge <$> a <*> b)
     where merge a b = mergeJusts <$> a <*> b <|> a <|> b
-          mergeJusts (env1, _) (env2, v) = (mergeEnvs env1 env2, v)
+          mergeJusts (_, env1) (v, env2) = (v, mergeEnvs env1 env2)
 
 instance Applicative m => Monoid (Merging m address value) where
   mappend = (<>)
@@ -113,7 +114,7 @@ instance Applicative m => Monoid (Merging m address value) where
 
 -- | An error thrown when loading a module from the list of provided modules. Indicates we weren't able to find a module with the given name.
 data LoadError address value resume where
-  ModuleNotFound :: ModulePath -> LoadError address value (Maybe (Environment address, value))
+  ModuleNotFound :: ModulePath -> LoadError address value (Maybe (value, Environment address))
 
 deriving instance Eq (LoadError address value resume)
 deriving instance Show (LoadError address value resume)
@@ -122,7 +123,7 @@ instance Show1 (LoadError address value) where
 instance Eq1 (LoadError address value) where
   liftEq _ (ModuleNotFound a) (ModuleNotFound b) = a == b
 
-moduleNotFound :: Member (Resumable (LoadError address value)) effects => ModulePath -> Evaluator address value effects (Maybe (Environment address, value))
+moduleNotFound :: Member (Resumable (LoadError address value)) effects => ModulePath -> Evaluator address value effects (Maybe (value, Environment address))
 moduleNotFound = throwResumable . ModuleNotFound
 
 resumeLoadError :: Member (Resumable (LoadError address value)) effects => Evaluator address value effects a -> (forall resume . LoadError address value resume -> Evaluator address value effects resume) -> Evaluator address value effects a

src/Control/Abstract/Primitive.hs

@@ -14,9 +14,9 @@ import Prologue
 
 builtin :: ( HasCallStack
            , Member (Allocator address value) effects
+           , Member (Env address) effects
            , Member (Reader ModuleInfo) effects
            , Member (Reader Span) effects
-           , Member (State (Environment address)) effects
            , Member (State (Heap address (Cell address) value)) effects
            , Ord address
            , Reducer value (Cell address value)
@@ -40,12 +40,11 @@ lambda body = do
 defineBuiltins :: ( AbstractValue address value effects
                   , HasCallStack
                   , Member (Allocator address value) effects
+                  , Member (Env address) effects
                   , Member Fresh effects
-                  , Member (Reader (Environment address)) effects
                   , Member (Reader ModuleInfo) effects
                   , Member (Reader Span) effects
                   , Member (Resumable (EnvironmentError address)) effects
-                  , Member (State (Environment address)) effects
                   , Member (State (Heap address (Cell address) value)) effects
                   , Member Trace effects
                   , Ord address

src/Control/Abstract/TermEvaluator.hs

@@ -7,7 +7,6 @@ module Control.Abstract.TermEvaluator
 
 import Control.Abstract.Evaluator
 import Control.Monad.Effect           as X
-import Control.Monad.Effect.Fail      as X
 import Control.Monad.Effect.Fresh     as X
 import Control.Monad.Effect.NonDet    as X
 import Control.Monad.Effect.Reader    as X

src/Control/Abstract/Value.hs

@@ -158,7 +158,7 @@ asBool value = ifthenelse value (pure True) (pure False)
 
 -- | C-style for loops.
 forLoop :: ( AbstractValue address value effects
-           , Member (State (Environment address)) effects
+           , Member (Env address) effects
            )
         => Evaluator address value effects value -- ^ Initial statement
         -> Evaluator address value effects value -- ^ Condition
@@ -187,7 +187,7 @@ doWhile body cond = loop $ \ continue -> body *> do
   ifthenelse this continue (pure unit)
 
 makeNamespace :: ( AbstractValue address value effects
-                 , Member (State (Environment address)) effects
+                 , Member (Env address) effects
                  , Member (State (Heap address (Cell address) value)) effects
                  , Ord address
                  , Reducer value (Cell address value)
@@ -206,7 +206,7 @@ makeNamespace name addr super = do
 
 -- | Evaluate a term within the context of the scoped environment of 'scopedEnvTerm'.
 evaluateInScopedEnv :: ( AbstractValue address value effects
-                       , Member (State (Environment address)) effects
+                       , Member (Env address) effects
                        )
                     => Evaluator address value effects value
                     -> Evaluator address value effects value
@@ -219,9 +219,8 @@ evaluateInScopedEnv scopedEnvTerm term = do
 -- | Evaluates a 'Value' returning the referenced value
 value :: ( AbstractValue address value effects
          , Member (Allocator address value) effects
-         , Member (Reader (Environment address)) effects
+         , Member (Env address) effects
          , Member (Resumable (EnvironmentError address)) effects
-         , Member (State (Environment address)) effects
          )
       => ValueRef value
       -> Evaluator address value effects value
@@ -232,9 +231,8 @@ value (Rval val) = pure val
 -- | Evaluates a 'Subterm' to its rval
 subtermValue :: ( AbstractValue address value effects
                 , Member (Allocator address value) effects
-                , Member (Reader (Environment address)) effects
+                , Member (Env address) effects
                 , Member (Resumable (EnvironmentError address)) effects
-                , Member (State (Environment address)) effects
                 )
              => Subterm term (Evaluator address value effects (ValueRef value))
              -> Evaluator address value effects value

src/Data/Abstract/Environment.hs

@@ -1,7 +1,6 @@
 module Data.Abstract.Environment
   ( Environment(..)
   , addresses
-  , intersect
   , delete
   , head
   , emptyEnv
@@ -10,6 +9,7 @@ module Data.Abstract.Environment
   , insert
   , lookup
   , names
+  , intersect
   , overwrite
   , pairs
   , unpairs

src/Data/Abstract/Evaluatable.hs

@@ -3,7 +3,6 @@ module Data.Abstract.Evaluatable
 ( module X
 , Evaluatable(..)
 , evaluatePackageWith
-, isolate
 , traceResolve
 -- | Effects
 , EvalError(..)
@@ -20,13 +19,11 @@ import Control.Abstract
 import Control.Abstract.Context as X
 import Control.Abstract.Environment as X hiding (runEnvironmentError, runEnvironmentErrorWith)
 import Control.Abstract.Evaluator as X hiding (LoopControl(..), Return(..), catchLoopControl, runLoopControl, catchReturn, runReturn)
-import Control.Abstract.Exports as X
 import Control.Abstract.Heap as X hiding (AddressError(..), runAddressError, runAddressErrorWith)
 import Control.Abstract.Modules as X (Modules, ResolutionError(..), load, lookupModule, listModulesInDir, require, resolve)
 import Control.Abstract.Value as X
 import Data.Abstract.Declarations as X
 import Data.Abstract.Environment as X
-import Data.Abstract.Exports as Exports
 import Data.Abstract.FreeVariables as X
 import Data.Abstract.Module
 import Data.Abstract.ModuleTable as ModuleTable
@@ -56,9 +53,9 @@ type EvaluatableConstraints address term value effects =
   , Declarations term
   , FreeVariables term
   , Member (Allocator address value) effects
+  , Member (Env address) effects
   , Member (LoopControl value) effects
   , Member (Modules address value) effects
-  , Member (Reader (Environment address)) effects
   , Member (Reader ModuleInfo) effects
   , Member (Reader PackageInfo) effects
   , Member (Reader Span) effects
@@ -67,8 +64,6 @@ type EvaluatableConstraints address term value effects =
   , Member (Resumable ResolutionError) effects
   , Member (Resumable (Unspecialized value)) effects
   , Member (Return value) effects
-  , Member (State (Environment address)) effects
-  , Member (State (Exports address)) effects
   , Member (State (Heap address (Cell address) value)) effects
   , Member Trace effects
   , Ord address
@@ -77,75 +72,65 @@ type EvaluatableConstraints address term value effects =
 
 
 -- | Evaluate a given package.
-evaluatePackageWith :: forall address term value inner outer
+evaluatePackageWith :: forall address term value inner inner' inner'' outer
-                    -- FIXME: It’d be nice if we didn’t have to mention 'Addressable' here at all, but 'Located' addresses require knowledge of 'currentModule' to run. Can we fix that? If not, can we factor this effect list out?
+                    -- FIXME: It’d be nice if we didn’t have to mention 'Addressable' here at all, but 'Located' locations require knowledge of 'currentModule' to run. Can we fix that?
-                    .  ( Addressable address (Reader ModuleInfo ': Modules address value ': Reader Span ': Reader PackageInfo ': outer)
+                    .  ( Addressable address inner'
                        , Evaluatable (Base term)
                        , EvaluatableConstraints address term value inner
                        , Member Fail outer
                        , Member Fresh outer
-                       , Member (Reader (Environment address)) outer
                        , Member (Resumable (AddressError address value)) outer
                        , Member (Resumable (LoadError address value)) outer
-                       , Member (State (Environment address)) outer
-                       , Member (State (Exports address)) outer
                        , Member (State (Heap address (Cell address) value)) outer
                        , Member (State (ModuleTable (Maybe (Environment address, value)))) outer
                        , Member Trace outer
                        , Recursive term
-                       , inner ~ (LoopControl value ': Return value ': Allocator address value ': Reader ModuleInfo ': Modules address value ': Reader Span ': Reader PackageInfo ': outer)
+                       , inner ~ (LoopControl value ': Return value ': Env address ': Allocator address value ': inner')
+                       , inner' ~ (Reader ModuleInfo ': inner'')
+                       , inner'' ~ (Modules address value ': Reader Span ': Reader PackageInfo ': outer)
                        )
                     => (SubtermAlgebra Module      term (TermEvaluator term address value inner value)            -> SubtermAlgebra Module      term (TermEvaluator term address value inner value))
                     -> (SubtermAlgebra (Base term) term (TermEvaluator term address value inner (ValueRef value)) -> SubtermAlgebra (Base term) term (TermEvaluator term address value inner (ValueRef value)))
                     -> Package term
-                    -> TermEvaluator term address value outer [value]
+                    -> TermEvaluator term address value outer [(value, Environment address)]
 evaluatePackageWith analyzeModule analyzeTerm package
   = runReader (packageInfo package)
   . runReader lowerBound
   . runReader (packageModules (packageBody package))
   . withPrelude (packagePrelude (packageBody package))
-  . raiseHandler (runModules (runTermEvaluator . evalModule))
+  $ \ preludeEnv
-  $ traverse (uncurry evaluateEntryPoint) (ModuleTable.toPairs (packageEntryPoints (packageBody package)))
+  ->  raiseHandler (runModules (runTermEvaluator . evalModule preludeEnv))
+    . traverse (uncurry (evaluateEntryPoint preludeEnv))
+    $ ModuleTable.toPairs (packageEntryPoints (packageBody package))
   where
-        evalModule m
+        evalModule preludeEnv m
-          = pairValueWithEnv
+          = runInModule preludeEnv (moduleInfo m)
-          . runInModule (moduleInfo m)
           . analyzeModule (subtermRef . moduleBody)
           $ evalTerm <$> m
         evalTerm term = Subterm term (TermEvaluator (value =<< runTermEvaluator (foldSubterms (analyzeTerm (TermEvaluator . eval . fmap (second runTermEvaluator))) term)))
 
-        runInModule info
+        runInModule preludeEnv info
           = runReader info
           . raiseHandler runAllocator
+          . raiseHandler (runEnv preludeEnv)
           . raiseHandler runReturn
           . raiseHandler runLoopControl
 
-        evaluateEntryPoint :: ModulePath -> Maybe Name -> TermEvaluator term address value (Modules address value ': Reader Span ': Reader PackageInfo ': outer) value
+        evaluateEntryPoint :: Environment address -> ModulePath -> Maybe Name -> TermEvaluator term address value inner'' (value, Environment address)
-        evaluateEntryPoint m sym = runInModule (ModuleInfo m) . TermEvaluator $ do
+        evaluateEntryPoint preludeEnv m sym = runInModule preludeEnv (ModuleInfo m) . TermEvaluator $ do
-          v <- maybe unit snd <$> require m
+          (env, value) <- fromMaybe (emptyEnv, unit) <$> require m
-          maybe (pure v) ((`call` []) <=< variable) sym
+          bindAll env
+          maybe (pure value) ((`call` []) <=< variable) sym
 
-        evalPrelude prelude = raiseHandler (runModules (runTermEvaluator . evalModule)) $ do
+        evalPrelude prelude = raiseHandler (runModules (runTermEvaluator . evalModule emptyEnv)) $ do
-          _ <- runInModule moduleInfoFromCallStack (TermEvaluator (defineBuiltins $> unit))
+          (_, builtinsEnv) <- runInModule emptyEnv moduleInfoFromCallStack (TermEvaluator (defineBuiltins $> unit))
-          fst <$> evalModule prelude
+          second (mergeEnvs builtinsEnv) <$> evalModule builtinsEnv prelude
 
-        withPrelude Nothing a = a
+        withPrelude Nothing f = f emptyEnv
-        withPrelude (Just prelude) a = do
+        withPrelude (Just prelude) f = do
-          preludeEnv <- evalPrelude prelude
+          (_, preludeEnv) <- evalPrelude prelude
-          raiseHandler (withDefaultEnvironment preludeEnv) a
+          f preludeEnv
 
-        -- TODO: If the set of exports is empty because no exports have been
-        -- defined, do we export all terms, or no terms? This behavior varies across
-        -- languages. We need better semantics rather than doing it ad-hoc.
-        filterEnv ports env
-          | Exports.null ports = env
-          | otherwise          = Exports.toEnvironment ports `mergeEnvs` overwrite (Exports.aliases ports) env
-        pairValueWithEnv action = flip (,) <$> action <*> (filterEnv <$> TermEvaluator getExports <*> TermEvaluator getEnv)
-
-
--- | Isolate the given action with an empty global environment and exports.
-isolate :: (Member (State (Environment address)) effects, Member (State (Exports address)) effects) => Evaluator address value effects a -> Evaluator address value effects a
-isolate = withEnv lowerBound . withExports lowerBound
 
 traceResolve :: (Show a, Show b, Member Trace effects) => a -> b -> Evaluator address value effects ()
 traceResolve name path = trace ("resolved " <> show name <> " -> " <> show path)

src/Data/Abstract/Ref.hs

@@ -12,3 +12,6 @@ data ValueRef value where
   -- | An object member.
   LvalMember :: value -> Name -> ValueRef value
   deriving (Eq, Ord, Show)
+
+
+newtype Ref address value = Ref address

src/Data/Abstract/Type.hs

@@ -117,21 +117,21 @@ instance AbstractIntro Type where
 
 
 instance ( Member (Allocator address Type) effects
+         , Member (Env address) effects
          , Member Fresh effects
          , Member (Resumable TypeError) effects
          , Member (Return Type) effects
-         , Member (State (Environment address)) effects
+         , Member (State (Heap address (Cell address) Type)) effects
-         , Member (State (Heap address (Cell address) Type)) effects
          , Ord address
          , Reducer Type (Cell address Type)
          )
       => AbstractFunction address Type effects where
   closure names _ body = do
     (env, tvars) <- foldr (\ name rest -> do
-      a <- alloc name
+      addr <- alloc name
       tvar <- Var <$> fresh
-      assign a tvar
+      assign addr tvar
-      bimap (Env.insert name a) (tvar :) <$> rest) (pure (emptyEnv, [])) names
+      bimap (Env.insert name addr) (tvar :) <$> rest) (pure (emptyEnv, [])) names
     (zeroOrMoreProduct tvars :->) <$> locally (bindAll env *> body `catchReturn` \ (Return value) -> pure value)
 
   call op params = do
@@ -146,12 +146,12 @@ instance ( Member (Allocator address Type) effects
 
 -- | Discard the value arguments (if any), constructing a 'Type' instead.
 instance ( Member (Allocator address Type) effects
+         , Member (Env address) effects
          , Member Fresh effects
          , Member NonDet effects
          , Member (Resumable TypeError) effects
          , Member (Return Type) effects
-         , Member (State (Environment address)) effects
+         , Member (State (Heap address (Cell address) Type)) effects
-         , Member (State (Heap address (Cell address) Type)) effects
          , Ord address
          , Reducer Type (Cell address Type)
          )

src/Data/Abstract/Value.hs

@@ -42,7 +42,7 @@ instance Ord  (ClosureBody address body) where
   compare = compare `on` closureBodyId
 
 instance Show (ClosureBody address body) where
-  showsPrec d (ClosureBody i _) = showsBinaryWith showsPrec (const showChar) "ClosureBody" d i '_'
+  showsPrec d (ClosureBody i _) = showsUnaryWith showsPrec "ClosureBody" d i
 
 
 instance Ord address => ValueRoots address (Value address body) where
@@ -56,12 +56,12 @@ instance AbstractHole (Value address body) where
 
 instance ( Coercible body (Eff effects)
          , Member (Allocator address (Value address body)) effects
+         , Member (Env address) effects
          , Member Fresh effects
          , Member (Reader ModuleInfo) effects
          , Member (Reader PackageInfo) effects
          , Member (Resumable (ValueError address body)) effects
          , Member (Return (Value address body)) effects
-         , Member (State (Environment address)) effects
          , Member (State (Heap address (Cell address) (Value address body))) effects
          , Ord address
          , Reducer (Value address body) (Cell address (Value address body))
@@ -72,7 +72,7 @@ instance ( Coercible body (Eff effects)
     packageInfo <- currentPackage
     moduleInfo <- currentModule
     i <- fresh
-    Closure packageInfo moduleInfo parameters (ClosureBody i (coerce (lowerEff body))) . Env.intersect (foldr Set.delete freeVariables parameters) <$> getEnv
+    Closure packageInfo moduleInfo parameters (ClosureBody i (coerce (lowerEff body))) <$> close (foldr Set.delete freeVariables parameters)
 
   call op params = do
     case op of
@@ -81,10 +81,10 @@ instance ( Coercible body (Eff effects)
         -- charge them to the closure's origin.
         withCurrentPackage packageInfo . withCurrentModule moduleInfo $ do
           bindings <- foldr (\ (name, param) rest -> do
-            v <- param
+            value <- param
-            a <- alloc name
+            addr <- alloc name
-            assign a v
+            assign addr value
-            Env.insert name a <$> rest) (pure env) (zip names params)
+            Env.insert name addr <$> rest) (pure env) (zip names params)
           locally (bindAll bindings *> raiseEff (coerce body) `catchReturn` \ (Return value) -> pure value)
       _ -> throwValueError (CallError op)
 
@@ -109,14 +109,13 @@ instance Show address => AbstractIntro (Value address body) where
 -- | Construct a 'Value' wrapping the value arguments (if any).
 instance ( Coercible body (Eff effects)
          , Member (Allocator address (Value address body)) effects
+         , Member (Env address) effects
          , Member Fresh effects
          , Member (LoopControl (Value address body)) effects
-         , Member (Reader (Environment address)) effects
          , Member (Reader ModuleInfo) effects
          , Member (Reader PackageInfo) effects
          , Member (Resumable (ValueError address body)) effects
          , Member (Return (Value address body)) effects
-         , Member (State (Environment address)) effects
          , Member (State (Heap address (Cell address) (Value address body))) effects
          , Ord address
          , Reducer (Value address body) (Cell address (Value address body))

src/Data/Syntax/Declaration.hs

@@ -27,8 +27,7 @@ instance Evaluatable Function where
   eval Function{..} = do
     name <- either (throwEvalError . FreeVariablesError) pure (freeVariable $ subterm functionName)
     (v, addr) <- letrec name (closure (paramNames functionParameters) (Set.fromList (freeVariables functionBody)) (subtermValue functionBody))
-    bind name addr
+    Rval v <$ bind name addr
-    pure (Rval v)
     where paramNames = foldMap (freeVariables . subterm)
 
 instance Declarations a => Declarations (Function a) where
@@ -53,8 +52,7 @@ instance Evaluatable Method where
   eval Method{..} = do
     name <- either (throwEvalError . FreeVariablesError) pure (freeVariable $ subterm methodName)
     (v, addr) <- letrec name (closure (paramNames methodParameters) (Set.fromList (freeVariables methodBody)) (subtermValue methodBody))
-    bind name addr
+    Rval v <$ bind name addr
-    pure (Rval v)
     where paramNames = foldMap (freeVariables . subterm)
 
 

src/Diffing/Algorithm.hs

@@ -221,7 +221,7 @@ instance Diffable [] where
 
 -- | Diff two non-empty lists using RWS.
 instance Diffable NonEmpty where
-  algorithmFor (a1:|as1) (a2:|as2) = nonEmpty <$> byRWS (a1:as1) (a2:as2) >>= maybe empty pure
+  algorithmFor (a1:|as1) (a2:|as2) = nonEmpty <$> byRWS (a1:as1) (a2:as2) >>= maybeM empty
 
   tryAlignWith f (a1:|as1) (a2:|as2) = (:|) <$> f (These a1 a2) <*> tryAlignWith f as1 as2
 

src/Language/Go/Syntax.hs

@@ -70,7 +70,7 @@ instance Evaluatable Import where
     paths <- resolveGoImport importPath
     for_ paths $ \path -> do
       traceResolve (unPath importPath) path
-      importedEnv <- maybe emptyEnv fst <$> isolate (require path)
+      importedEnv <- maybe emptyEnv fst <$> require path
       bindAll importedEnv
     pure (Rval unit)
 
@@ -94,7 +94,7 @@ instance Evaluatable QualifiedImport where
     void $ letrec' alias $ \addr -> do
       for_ paths $ \p -> do
         traceResolve (unPath importPath) p
-        importedEnv <- maybe emptyEnv fst <$> isolate (require p)
+        importedEnv <- maybe emptyEnv fst <$> require p
         bindAll importedEnv
       makeNamespace alias addr Nothing
     pure (Rval unit)
@@ -113,7 +113,7 @@ instance Evaluatable SideEffectImport where
   eval (SideEffectImport importPath _) = do
     paths <- resolveGoImport importPath
     traceResolve (unPath importPath) paths
-    for_ paths $ \path -> isolate (require path)
+    for_ paths require
     pure (Rval unit)
 
 -- A composite literal in Go

src/Language/PHP/Syntax.hs

@@ -48,18 +48,16 @@ resolvePHPName :: ( Member (Modules address value) effects
                -> Evaluator address value effects ModulePath
 resolvePHPName n = do
   modulePath <- resolve [name]
-  maybe (throwResumable $ NotFoundError name [name] Language.PHP) pure modulePath
+  maybeM (throwResumable $ NotFoundError name [name] Language.PHP) modulePath
   where name = toName n
         toName = BC.unpack . dropRelativePrefix . stripQuotes
 
 include :: ( AbstractValue address value effects
            , Member (Allocator address value) effects
+           , Member (Env address) effects
            , Member (Modules address value) effects
-           , Member (Reader (Environment address)) effects
            , Member (Resumable ResolutionError) effects
            , Member (Resumable (EnvironmentError address)) effects
-           , Member (State (Environment address)) effects
-           , Member (State (Exports address)) effects
            , Member Trace effects
            )
         => Subterm term (Evaluator address value effects (ValueRef value))
@@ -69,7 +67,7 @@ include pathTerm f = do
   name <- subtermValue pathTerm >>= asString
   path <- resolvePHPName name
   traceResolve name path
-  (importedEnv, v) <- isolate (f path) >>= maybeM (pure (emptyEnv, unit))
+  (importedEnv, v) <- fromMaybe (emptyEnv, unit) <$> f path
   bindAll importedEnv
   pure (Rval v)
 

src/Language/Python/Syntax.hs

@@ -82,7 +82,7 @@ resolvePythonModules q = do
                         , path <.> ".py"
                         ]
       modulePath <- resolve searchPaths
-      maybe (throwResumable $ NotFoundError path searchPaths Language.Python) pure modulePath
+      maybeM (throwResumable $ NotFoundError path searchPaths Language.Python) modulePath
 
 
 -- | Import declarations (symbols are added directly to the calling environment).
@@ -113,11 +113,11 @@ instance Evaluatable Import where
     modulePaths <- resolvePythonModules name
 
     -- Eval parent modules first
-    for_ (NonEmpty.init modulePaths) (isolate . require)
+    for_ (NonEmpty.init modulePaths) require
 
     -- Last module path is the one we want to import
     let path = NonEmpty.last modulePaths
-    importedEnv <- maybe emptyEnv fst <$> isolate (require path)
+    importedEnv <- maybe emptyEnv fst <$> require path
     bindAll (select importedEnv)
     pure (Rval unit)
     where
@@ -129,17 +129,15 @@ instance Evaluatable Import where
 -- Evaluate a qualified import
 evalQualifiedImport :: ( AbstractValue address value effects
                        , Member (Allocator address value) effects
+                       , Member (Env address) effects
                        , Member (Modules address value) effects
-                       , Member (Reader (Environment address)) effects
-                       , Member (State (Environment address)) effects
-                       , Member (State (Exports address)) effects
                        , Member (State (Heap address (Cell address) value)) effects
                        , Ord address
                        , Reducer.Reducer value (Cell address value)
                        )
                     => Name -> ModulePath -> Evaluator address value effects value
 evalQualifiedImport name path = letrec' name $ \addr -> do
-  importedEnv <- maybe emptyEnv fst <$> isolate (require path)
+  importedEnv <- maybe emptyEnv fst <$> require path
   bindAll importedEnv
   unit <$ makeNamespace name addr Nothing
 
@@ -163,7 +161,7 @@ instance Evaluatable QualifiedImport where
       go ((name, path) :| []) = evalQualifiedImport name path
       -- Evaluate each parent module, just creating a namespace
       go ((name, path) :| xs) = letrec' name $ \addr -> do
-        void $ isolate (require path)
+        void $ require path
         void $ go (NonEmpty.fromList xs)
         makeNamespace name addr Nothing
 
@@ -182,13 +180,13 @@ instance Evaluatable QualifiedAliasedImport where
     modulePaths <- resolvePythonModules name
 
     -- Evaluate each parent module
-    for_ (NonEmpty.init modulePaths) (isolate . require)
+    for_ (NonEmpty.init modulePaths) require
 
     -- Evaluate and import the last module, aliasing and updating the environment
     alias <- either (throwEvalError . FreeVariablesError) pure (freeVariable $ subterm aliasTerm)
     Rval <$> letrec' alias (\addr -> do
       let path = NonEmpty.last modulePaths
-      importedEnv <- maybe emptyEnv fst <$> isolate (require path)
+      importedEnv <- maybe emptyEnv fst <$> require path
       bindAll importedEnv
       unit <$ makeNamespace alias addr Nothing)
 

src/Language/Ruby/Syntax.hs

@@ -26,7 +26,7 @@ resolveRubyName name = do
   let name' = cleanNameOrPath name
   let paths = [name' <.> "rb"]
   modulePath <- resolve paths
-  maybe (throwResumable $ NotFoundError name' paths Language.Ruby) pure modulePath
+  maybeM (throwResumable $ NotFoundError name' paths Language.Ruby) modulePath
 
 -- load "/root/src/file.rb"
 resolveRubyPath :: ( Member (Modules address value) effects
@@ -37,7 +37,7 @@ resolveRubyPath :: ( Member (Modules address value) effects
 resolveRubyPath path = do
   let name' = cleanNameOrPath path
   modulePath <- resolve [name']
-  maybe (throwResumable $ NotFoundError name' [name'] Language.Ruby) pure modulePath
+  maybeM (throwResumable $ NotFoundError name' [name'] Language.Ruby) modulePath
 
 cleanNameOrPath :: ByteString -> String
 cleanNameOrPath = BC.unpack . dropRelativePrefix . stripQuotes
@@ -73,7 +73,7 @@ instance Evaluatable Require where
     name <- subtermValue x >>= asString
     path <- resolveRubyName name
     traceResolve name path
-    (importedEnv, v) <- isolate (doRequire path)
+    (importedEnv, v) <- doRequire path
     bindAll importedEnv
     pure (Rval v) -- Returns True if the file was loaded, False if it was already loaded. http://ruby-doc.org/core-2.5.0/Kernel.html#method-i-require
 
@@ -109,10 +109,9 @@ instance Evaluatable Load where
   eval (Load _) = raiseEff (fail "invalid argument supplied to load, path is required")
 
 doLoad :: ( AbstractValue address value effects
+          , Member (Env address) effects
           , Member (Modules address value) effects
           , Member (Resumable ResolutionError) effects
-          , Member (State (Environment address)) effects
-          , Member (State (Exports address)) effects
           , Member Trace effects
           )
        => ByteString
@@ -121,7 +120,7 @@ doLoad :: ( AbstractValue address value effects
 doLoad path shouldWrap = do
   path' <- resolveRubyPath path
   traceResolve path path'
-  importedEnv <- maybe emptyEnv fst <$> isolate (load path')
+  importedEnv <- maybe emptyEnv fst <$> load path'
   unless shouldWrap $ bindAll importedEnv
   pure (boolean Prelude.True) -- load always returns true. http://ruby-doc.org/core-2.5.0/Kernel.html#method-i-load
 

src/Language/TypeScript/Syntax.hs

@@ -135,10 +135,8 @@ javascriptExtensions = ["js"]
 
 evalRequire :: ( AbstractValue address value effects
                , Member (Allocator address value) effects
+               , Member (Env address) effects
                , Member (Modules address value) effects
-               , Member (Reader (Environment address)) effects
-               , Member (State (Environment address)) effects
-               , Member (State (Exports address)) effects
                , Member (State (Heap address (Cell address) value)) effects
                , Ord address
                , Reducer value (Cell address value)
@@ -147,7 +145,7 @@ evalRequire :: ( AbstractValue address value effects
             -> Name
             -> Evaluator address value effects value
 evalRequire modulePath alias = letrec' alias $ \addr -> do
-  importedEnv <- maybe emptyEnv fst <$> isolate (require modulePath)
+  importedEnv <- maybe emptyEnv fst <$> require modulePath
   bindAll importedEnv
   unit <$ makeNamespace alias addr Nothing
 
@@ -164,7 +162,7 @@ instance Show1 Import where liftShowsPrec = genericLiftShowsPrec
 instance Evaluatable Import where
   eval (Import symbols importPath) = do
     modulePath <- resolveWithNodejsStrategy importPath typescriptExtensions
-    importedEnv <- maybe emptyEnv fst <$> isolate (require modulePath)
+    importedEnv <- maybe emptyEnv fst <$> require modulePath
     bindAll (renamed importedEnv) $> Rval unit
     where
       renamed importedEnv
@@ -214,7 +212,7 @@ instance ToJSONFields1 SideEffectImport
 instance Evaluatable SideEffectImport where
   eval (SideEffectImport importPath) = do
     modulePath <- resolveWithNodejsStrategy importPath typescriptExtensions
-    void $ isolate (require modulePath)
+    void $ require modulePath
     pure (Rval unit)
 
 
@@ -232,7 +230,7 @@ instance Evaluatable QualifiedExport where
   eval (QualifiedExport exportSymbols) = do
     -- Insert the aliases with no addresses.
     for_ exportSymbols $ \(name, alias) ->
-      addExport name alias Nothing
+      export name alias Nothing
     pure (Rval unit)
 
 
@@ -249,11 +247,11 @@ instance ToJSONFields1 QualifiedExportFrom
 instance Evaluatable QualifiedExportFrom where
   eval (QualifiedExportFrom importPath exportSymbols) = do
     modulePath <- resolveWithNodejsStrategy importPath typescriptExtensions
-    importedEnv <- maybe emptyEnv fst <$> isolate (require modulePath)
+    importedEnv <- maybe emptyEnv fst <$> require modulePath
     -- Look up addresses in importedEnv and insert the aliases with addresses into the exports.
     for_ exportSymbols $ \(name, alias) -> do
       let address = Env.lookup name importedEnv
-      maybe (throwEvalError $ ExportError modulePath name) (addExport name alias . Just) address
+      maybe (throwEvalError $ ExportError modulePath name) (export name alias . Just) address
     pure (Rval unit)
 
 newtype DefaultExport a = DefaultExport { defaultExport :: a }
@@ -272,8 +270,8 @@ instance Evaluatable DefaultExport where
       Just name -> do
         addr <- lookupOrAlloc name
         assign addr v
-        addExport name name Nothing
+        export name name Nothing
-        void $ bind name addr
+        bind name addr
       Nothing -> throwEvalError DefaultExportError
     pure (Rval unit)
 

src/Semantic/Graph.hs

@@ -129,7 +129,7 @@ resumingAddressError = runAddressErrorWith (\ err -> trace ("AddressError:" <> s
   UnallocatedAddress _   -> pure lowerBound
   UninitializedAddress _ -> pure hole)
 
-resumingValueError :: (Member (State (Environment address)) effects, Member Trace effects, Show address) => Evaluator address (Value address body) (Resumable (ValueError address body) ': effects) a -> Evaluator address (Value address body) effects a
+resumingValueError :: (Member Trace effects, Show address) => Evaluator address (Value address body) (Resumable (ValueError address body) ': effects) a -> Evaluator address (Value address body) effects a
 resumingValueError = runValueErrorWith (\ err -> trace ("ValueError" <> show err) *> case err of
   CallError val     -> pure val
   StringError val   -> pure (pack (show val))
@@ -139,7 +139,7 @@ resumingValueError = runValueErrorWith (\ err -> trace ("ValueError" <> show err
   NumericError{}    -> pure hole
   Numeric2Error{}   -> pure hole
   ComparisonError{} -> pure hole
-  NamespaceError{}  -> getEnv
+  NamespaceError{}  -> pure emptyEnv
   BitwiseError{}    -> pure hole
   Bitwise2Error{}   -> pure hole
   KeyValueError{}   -> pure (hole, hole)

src/Semantic/IO.hs

@@ -96,7 +96,7 @@ readBlobsFromHandle = fmap toBlobs . readFromHandle
 readBlobFromPath :: MonadIO m => File -> m Blob.Blob
 readBlobFromPath file = do
   maybeFile <- readFile file
-  maybe (fail ("cannot read '" <> show file <> "', file not found or language not supported.")) pure maybeFile
+  maybeM (fail ("cannot read '" <> show file <> "', file not found or language not supported.")) maybeFile
 
 readProjectFromPaths :: MonadIO m => Maybe FilePath -> FilePath -> Language -> [FilePath] -> m Project
 readProjectFromPaths maybeRoot path lang excludeDirs = do

test/Analysis/Go/Spec.hs

@@ -11,16 +11,16 @@ spec :: Spec
 spec = parallel $ do
   describe "evaluates Go" $ do
     it "imports and wildcard imports" $ do
-      ((_, state), _) <- evaluate "main.go"
+      ((Right [(_, env)], state), _) <- evaluate "main.go"
-      Env.names (environment state) `shouldBe` [ "Bar", "Rab", "foo", "main" ]
+      Env.names env `shouldBe` [ "Bar", "Rab", "foo", "main" ]
 
-      (derefQName (heap state) ("foo" :| []) (environment state) >>= deNamespace) `shouldBe` Just ("foo",  ["New"])
+      (derefQName (heap state) ("foo" :| []) env >>= deNamespace) `shouldBe` Just ("foo",  ["New"])
 
     it "imports with aliases (and side effects only)" $ do
-      ((_, state), _) <- evaluate "main1.go"
+      ((Right [(_, env)], state), _) <- evaluate "main1.go"
-      Env.names (environment state) `shouldBe` [ "f", "main" ]
+      Env.names env `shouldBe` [ "f", "main" ]
 
-      (derefQName (heap state) ("f" :| []) (environment state) >>= deNamespace) `shouldBe` Just ("f",  ["New"])
+      (derefQName (heap state) ("f" :| []) env >>= deNamespace) `shouldBe` Just ("f",  ["New"])
 
   where
     fixtures = "test/fixtures/go/analysis/"

test/Analysis/PHP/Spec.hs

@@ -12,22 +12,22 @@ spec :: Spec
 spec = parallel $ do
   describe "PHP" $ do
     it "evaluates include and require" $ do
-      ((res, state), _) <- evaluate "main.php"
+      ((Right [(res, env)], state), _) <- evaluate "main.php"
-      res `shouldBe` Right [unit]
+      res `shouldBe` unit
-      Env.names (environment state) `shouldBe` [ "bar", "foo" ]
+      Env.names env `shouldBe` [ "bar", "foo" ]
 
     it "evaluates include_once and require_once" $ do
-      ((res, state), _) <- evaluate "main_once.php"
+      ((Right [(res, env)], state), _) <- evaluate "main_once.php"
-      res `shouldBe` Right [unit]
+      res `shouldBe` unit
-      Env.names (environment state) `shouldBe` [ "bar", "foo" ]
+      Env.names env `shouldBe` [ "bar", "foo" ]
 
     it "evaluates namespaces" $ do
-      ((_, state), _) <- evaluate "namespaces.php"
+      ((Right [(_, env)], state), _) <- evaluate "namespaces.php"
-      Env.names (environment state) `shouldBe` [ "Foo", "NS1" ]
+      Env.names env `shouldBe` [ "Foo", "NS1" ]
 
-      (derefQName (heap state) ("NS1" :| [])               (environment state) >>= deNamespace) `shouldBe` Just ("NS1",  ["Sub1", "b", "c"])
+      (derefQName (heap state) ("NS1" :| [])               env >>= deNamespace) `shouldBe` Just ("NS1",  ["Sub1", "b", "c"])
-      (derefQName (heap state) ("NS1" :| ["Sub1"])         (environment state) >>= deNamespace) `shouldBe` Just ("Sub1", ["Sub2"])
+      (derefQName (heap state) ("NS1" :| ["Sub1"])         env >>= deNamespace) `shouldBe` Just ("Sub1", ["Sub2"])
-      (derefQName (heap state) ("NS1" :| ["Sub1", "Sub2"]) (environment state) >>= deNamespace) `shouldBe` Just ("Sub2", ["f"])
+      (derefQName (heap state) ("NS1" :| ["Sub1", "Sub2"]) env >>= deNamespace) `shouldBe` Just ("Sub2", ["f"])
 
   where
     fixtures = "test/fixtures/php/analysis/"

test/Analysis/Python/Spec.hs

@@ -14,33 +14,33 @@ spec :: Spec
 spec = parallel $ do
   describe "evaluates Python" $ do
     it "imports" $ do
-      ((_, state), _) <- evaluate "main.py"
+      ((Right [(_, env)], state), _) <- evaluate "main.py"
-      Env.names (environment state) `shouldContain` [ "a", "b" ]
+      Env.names env `shouldContain` [ "a", "b" ]
 
-      (derefQName (heap state) ("a" :| [])    (environment state) >>= deNamespace) `shouldBe` Just ("a", ["foo"])
+      (derefQName (heap state) ("a" :| [])    env >>= deNamespace) `shouldBe` Just ("a", ["foo"])
-      (derefQName (heap state) ("b" :| [])    (environment state) >>= deNamespace) `shouldBe` Just ("b", ["c"])
+      (derefQName (heap state) ("b" :| [])    env >>= deNamespace) `shouldBe` Just ("b", ["c"])
-      (derefQName (heap state) ("b" :| ["c"]) (environment state) >>= deNamespace) `shouldBe` Just ("c", ["baz"])
+      (derefQName (heap state) ("b" :| ["c"]) env >>= deNamespace) `shouldBe` Just ("c", ["baz"])
 
     it "imports with aliases" $ do
-      env <- environment . snd . fst <$> evaluate "main1.py"
+      ((Right [(_, env)], _), _) <- evaluate "main1.py"
       Env.names env `shouldContain` [ "b", "e" ]
 
     it "imports using 'from' syntax" $ do
-      env <- environment . snd . fst <$> evaluate "main2.py"
+      ((Right [(_, env)], _), _) <- evaluate "main2.py"
       Env.names env `shouldContain` [ "bar", "foo" ]
 
     it "imports with relative syntax" $ do
-      ((_, state), _) <- evaluate "main3.py"
+      ((Right [(_, env)], state), _) <- evaluate "main3.py"
-      Env.names (environment state) `shouldContain` [ "utils" ]
+      Env.names env `shouldContain` [ "utils" ]
-      (derefQName (heap state) ("utils" :| []) (environment state) >>= deNamespace) `shouldBe` Just ("utils", ["to_s"])
+      (derefQName (heap state) ("utils" :| []) env >>= deNamespace) `shouldBe` Just ("utils", ["to_s"])
 
     it "subclasses" $ do
       ((res, _), _) <- evaluate "subclass.py"
-      res `shouldBe` Right [String "\"bar\""]
+      fmap fst <$> res `shouldBe` Right [String "\"bar\""]
 
     it "handles multiple inheritance left-to-right" $ do
       ((res, _), _) <- evaluate "multiple_inheritance.py"
-      res `shouldBe` Right [String "\"foo!\""]
+      fmap fst <$> res `shouldBe` Right [String "\"foo!\""]
 
   where
     ns n = Just . Latest . Last . Just . Namespace n

test/Analysis/Ruby/Spec.hs

@@ -20,58 +20,57 @@ spec :: Spec
 spec = parallel $ do
   describe "Ruby" $ do
     it "evaluates require_relative" $ do
-      ((res, state), _) <- evaluate "main.rb"
+      ((Right [(res, env)], state), _) <- evaluate "main.rb"
-      res `shouldBe` Right [Value.Integer (Number.Integer 1)]
+      res `shouldBe` Value.Integer (Number.Integer 1)
-      Env.names (environment state) `shouldContain` ["foo"]
+      Env.names env `shouldContain` ["foo"]
 
     it "evaluates load" $ do
-      env <- environment . snd . fst <$> evaluate "load.rb"
+      ((Right [(_, env)], _), _) <- evaluate "load.rb"
       Env.names env `shouldContain` ["foo"]
 
     it "evaluates load with wrapper" $ do
       ((res, state), _) <- evaluate "load-wrap.rb"
       res `shouldBe` Left (SomeExc (inject @(EnvironmentError Precise) (FreeVariable "foo")))
-      Env.names (environment state) `shouldContain` [ "Object" ]
 
     it "evaluates subclass" $ do
-      ((res, state), _) <- evaluate "subclass.rb"
+      ((Right [(res, env)], state), _) <- evaluate "subclass.rb"
-      res `shouldBe` Right [String "\"<bar>\""]
+      res `shouldBe` String "\"<bar>\""
-      Env.names (environment state) `shouldContain` [ "Bar", "Foo" ]
+      Env.names env `shouldContain` [ "Bar", "Foo" ]
 
-      (derefQName (heap state) ("Bar" :| []) (environment state) >>= deNamespace) `shouldBe` Just ("Bar",  ["baz", "foo", "inspect"])
+      (derefQName (heap state) ("Bar" :| []) env >>= deNamespace) `shouldBe` Just ("Bar",  ["baz", "foo", "inspect"])
 
     it "evaluates modules" $ do
-      ((res, state), _) <- evaluate "modules.rb"
+      ((Right [(res, env)], state), _) <- evaluate "modules.rb"
-      res `shouldBe` Right [String "\"<hello>\""]
+      res `shouldBe` String "\"<hello>\""
-      Env.names (environment state) `shouldContain` [ "Bar" ]
+      Env.names env `shouldContain` [ "Bar" ]
 
     it "handles break correctly" $ do
       ((res, _), _) <- evaluate "break.rb"
-      res `shouldBe` Right [Value.Integer (Number.Integer 3)]
+      fmap fst <$> res `shouldBe` Right [Value.Integer (Number.Integer 3)]
 
     it "handles break correctly" $ do
       ((res, _), _) <- evaluate "next.rb"
-      res `shouldBe` Right [Value.Integer (Number.Integer 8)]
+      fmap fst <$> res `shouldBe` Right [Value.Integer (Number.Integer 8)]
 
     it "calls functions with arguments" $ do
       ((res, _), _) <- evaluate "call.rb"
-      res `shouldBe` Right [Value.Integer (Number.Integer 579)]
+      fmap fst <$> res `shouldBe` Right [Value.Integer (Number.Integer 579)]
 
     it "evaluates early return statements" $ do
       ((res, _), _) <- evaluate "early-return.rb"
-      res `shouldBe` Right [Value.Integer (Number.Integer 123)]
+      fmap fst <$> res `shouldBe` Right [Value.Integer (Number.Integer 123)]
 
     it "has prelude" $ do
       ((res, _), _) <- evaluate "preluded.rb"
-      res `shouldBe` Right [String "\"<foo>\""]
+      fmap fst <$> res `shouldBe` Right [String "\"<foo>\""]
 
     it "evaluates __LINE__" $ do
       ((res, _), _) <- evaluate "line.rb"
-      res `shouldBe` Right [Value.Integer (Number.Integer 4)]
+      fmap fst <$> res `shouldBe` Right [Value.Integer (Number.Integer 4)]
 
     it "resolves builtins used in the prelude" $ do
       ((res, _), traces) <- evaluate "puts.rb"
-      res `shouldBe` Right [Unit]
+      fmap fst <$> res `shouldBe` Right [Unit]
       traces `shouldContain` [ "\"hello\"" ]
 
   where

test/Analysis/TypeScript/Spec.hs

@@ -15,19 +15,19 @@ spec :: Spec
 spec = parallel $ do
   describe "evaluates TypeScript" $ do
     it "imports with aliased symbols" $ do
-      env <- environment . snd . fst <$> evaluate "main.ts"
+      ((Right [(_, env)], _), _) <- evaluate "main.ts"
       Env.names env `shouldBe` [ "bar", "quz" ]
 
     it "imports with qualified names" $ do
-      ((_, state), _) <- evaluate "main1.ts"
+      ((Right [(_, env)], state), _) <- evaluate "main1.ts"
-      Env.names (environment state) `shouldBe` [ "b", "z" ]
+      Env.names env `shouldBe` [ "b", "z" ]
 
-      (derefQName (heap state) ("b" :| []) (environment state) >>= deNamespace) `shouldBe` Just ("b", [ "baz", "foo" ])
+      (derefQName (heap state) ("b" :| []) env >>= deNamespace) `shouldBe` Just ("b", [ "baz", "foo" ])
-      (derefQName (heap state) ("z" :| []) (environment state) >>= deNamespace) `shouldBe` Just ("z", [ "baz", "foo" ])
+      (derefQName (heap state) ("z" :| []) env >>= deNamespace) `shouldBe` Just ("z", [ "baz", "foo" ])
 
     it "side effect only imports" $ do
-      env <- environment . snd . fst <$> evaluate "main2.ts"
+      ((res, _), _) <- evaluate "main2.ts"
-      env `shouldBe` emptyEnv
+      fmap snd <$> res `shouldBe` Right [emptyEnv]
 
     it "fails exporting symbols not defined in the module" $ do
       ((res, _), _) <- evaluate "bad-export.ts"
@@ -35,7 +35,7 @@ spec = parallel $ do
 
     it "evaluates early return statements" $ do
       ((res, _), _) <- evaluate "early-return.ts"
-      res `shouldBe` Right [Value.Float (Number.Decimal 123.0)]
+      fmap fst <$> res `shouldBe` Right [Value.Float (Number.Decimal 123.0)]
 
   where
     fixtures = "test/fixtures/typescript/analysis/"

test/Control/Abstract/Evaluator/Spec.hs

@@ -20,13 +20,13 @@ spec :: Spec
 spec = parallel $ do
   it "constructs integers" $ do
     (expected, _) <- evaluate (pure (integer 123))
-    expected `shouldBe` Right (Value.Integer (Number.Integer 123))
+    fst <$> expected `shouldBe` Right (Value.Integer (Number.Integer 123))
 
   it "calls functions" $ do
     (expected, _) <- evaluate $ do
       identity <- closure [name "x"] lowerBound (variable (name "x"))
       call identity [pure (integer 123)]
-    expected `shouldBe` Right (Value.Integer (Number.Integer 123))
+    fst <$> expected `shouldBe` Right (Value.Integer (Number.Integer 123))
 
 evaluate
   = runM
@@ -38,6 +38,7 @@ evaluate
   . runEnvironmentError
   . runAddressError
   . runAllocator
+  . runEnv lowerBound
   . runReturn
   . runLoopControl
 

test/SpecHelpers.hs

@@ -34,7 +34,6 @@ import Data.Project as X
 import Data.Functor.Listable as X
 import Data.Language as X
 import Data.List.NonEmpty as X (NonEmpty(..))
-import Data.Monoid as X (Last(..))
 import Data.Range as X
 import Data.Record as X
 import Data.Source as X