Elm step A: GC working

elm/Env.elm

@@ -11,7 +11,6 @@ module Env
         , push
         , pop
         , enter
-        , jump
         , leave
         , ref
         , pushRef
@@ -54,6 +53,7 @@ global =
     , gcInterval = defaultGcInterval
     , gcCounter = 0
     , stack = []
+    , keepFrames = []
     }
 
 
@@ -220,29 +220,6 @@ enter outerId binds env =
         }
 
 
-{-| Jump into a frame
--}
-jump : Int -> Env -> Env
-jump frameId env =
-    let
-        setExitId =
-            Maybe.map
-                (\frame ->
-                    { frame
-                        | exitId = Just env.currentFrameId
-                        , refCnt = frame.refCnt + 1
-                    }
-                )
-
-        bogus =
-            debug env "jump #" frameId
-    in
-        { env
-            | currentFrameId = frameId
-            , frames = Dict.update frameId setExitId env.frames
-        }
-
-
 leave : Env -> Env
 leave env =
     let
@@ -332,8 +309,6 @@ Return a new Env with the unreachable frames removed.
 gc : MalExpr -> Env -> Env
 gc expr env =
     let
-        -- bogus =
-        --     Debug.log "GC stack = " env.stack
         countList acc =
             List.foldl countExpr acc
 
@@ -387,7 +362,10 @@ gc expr env =
                     acc
 
         initSet =
-            Set.fromList [ globalFrameId, env.currentFrameId ]
+            Set.fromList
+                ([ globalFrameId, env.currentFrameId ]
+                    ++ env.keepFrames
+                )
 
         countFrames frames acc =
             Set.toList frames
@@ -437,16 +415,10 @@ gc expr env =
 
         filterFrames frames keep =
             Dict.filter (keepFilter keep) frames
-
-        reportUnused frames keep =
-            Set.diff (Set.fromList (Dict.keys frames)) keep
-                |> Debug.log "\n\nUNUSED FRAMES\n\n"
-                |> always keep
     in
         countFrames initSet initSet
             |> countExpr expr
             |> (flip countList) env.stack
             |> loop
-            --            |> reportUnused env.frames
             |> filterFrames env.frames
             |> makeNewEnv

elm/Eval.elm

@@ -3,7 +3,6 @@ module Eval exposing (..)
 import Types exposing (..)
 import IO exposing (IO)
 import Env
-import Printer exposing (printEnv)
 
 
 apply : Eval a -> Env -> EvalContext a
@@ -197,3 +196,30 @@ pushRef : MalExpr -> Eval a -> Eval a
 pushRef ref e =
     modifyEnv (Env.pushRef ref)
         |> andThen (always e)
+
+
+inGlobal : Eval a -> Eval a
+inGlobal body =
+    let
+        enter env =
+            setEnv
+                { env
+                    | keepFrames = env.currentFrameId :: env.keepFrames
+                    , currentFrameId = Env.globalFrameId
+                }
+
+        leave oldEnv newEnv =
+            { newEnv
+                | keepFrames = oldEnv.keepFrames
+                , currentFrameId = oldEnv.currentFrameId
+            }
+    in
+        withEnv
+            (\env ->
+                if env.currentFrameId /= Env.globalFrameId then
+                    enter env
+                        |> andThen (always body)
+                        |> finally (leave env)
+                else
+                    body
+            )

elm/Types.elm

@@ -32,6 +32,7 @@ type alias Env =
     , gcInterval : Int
     , gcCounter : Int
     , stack : List MalExpr
+    , keepFrames : List Int
     }
 
 

elm/stepA_mal.elm

@@ -273,12 +273,7 @@ malEval : List MalExpr -> Eval MalExpr
 malEval args =
     case args of
         [ expr ] ->
-            Eval.withEnv
-                (\env ->
-                    Eval.modifyEnv (Env.jump Env.globalFrameId)
-                        |> Eval.andThen (\_ -> eval expr)
-                        |> Eval.finally Env.leave
-                )
+            Eval.inGlobal (eval expr)
 
         _ ->
             Eval.fail "unsupported arguments"