Merge pull request #16 from purescript-contrib/avoid-ffi

Avoid ffi

Author: paf31

MODULE.md

@@ -50,7 +50,7 @@
 ### Types
 
     newtype Yoneda f a where
-      Yoneda :: forall b. (a -> b) -> f b -> Yoneda f a
+      Yoneda :: (forall b. (a -> b) -> f b) -> Yoneda f a
 
 
 ### Type Class Instances
@@ -126,7 +126,7 @@
     data Free f a where
       Pure :: a -> Free f a
       Free :: f (Free f a) -> Free f a
-      Gosub :: forall s. (forall r. (Unit -> Free f r) -> (r -> Free f a) -> s) -> s -> Free f a
+      Gosub :: (forall s. (forall r. (Unit -> Free f r) -> (r -> Free f a) -> s) -> s) -> Free f a
 
     type FreeC f a = Free (Coyoneda f) a
 
@@ -181,7 +181,7 @@
 
 ### Types
 
-    type Trampoline  = Free Lazy
+    type Trampoline = Free Lazy
 
 
 ### Values

src/Control/Monad/Free.purs

@@ -81,58 +81,24 @@ resumeGosub (Gosub f) = f (\a g ->
     Gosub h -> Right (h (\b i -> b unit >>= (\x -> i x >>= g)))
   )
 
-isGosub :: forall f a. Free f a -> Boolean
-isGosub (Gosub _) = true
-isGosub _ = false
-
-unsafeFreeToEither :: forall f a. Free f a -> Either (f (Free f a)) a
-unsafeFreeToEither (Pure x) = Right x
-unsafeFreeToEither (Free x) = Left x
-
 unsafeLeft :: forall a b. Either a b -> a
 unsafeLeft (Left x) = x
 
 unsafeRight :: forall a b. Either a b -> b
 unsafeRight (Right x) = x
 
-foreign import resumeImpl
-  "function resumeImpl(isGosub, isLeft, toEither, fromRight, resumeGosub, value) {\
-  \  while (true) {\
-  \    if (!isGosub(value)) return toEither(value);\
-  \    var x = resumeGosub(value);\
-  \    if (isLeft(x)) return x;\
-  \    else value = fromRight(x);\
-  \  }\
-  \}" :: forall f a. Fn6
-         (Free f a -> Boolean)
-         (Either (f (Free f a)) a -> Boolean)
-         (Free f a -> Either (f (Free f a)) a)
-         (Either (f (Free f a)) a -> a)
-         (Free f a -> Either (f (Free f a)) (Free f a))
-         (Free f a)
-         (Either (f (Free f a)) a)
-
 resume :: forall f a. (Functor f) => Free f a -> Either (f (Free f a)) a
-resume f = runFn6 resumeImpl isGosub isLeft unsafeFreeToEither unsafeRight resumeGosub f
-
-foreign import goImpl
-  "function goImpl(resume, isRight, fromLeft, fromRight, fn, value) {\
-  \  while (true) {\
-  \    var r = resume(value);\
-  \    if (isRight(r)) return fromRight(r);\
-  \    value = fn(fromLeft(r));\
-  \  }\
-  \}" :: forall f a. Fn6
-         (Free f a -> Either (f (Free f a)) a)
-         (Either (f (Free f a)) a -> Boolean)
-         (Either (f (Free f a)) a -> (f (Free f a)))
-         (Either (f (Free f a)) a -> a)
-         (f (Free f a) -> Free f a)
-         (Free f a)
-         a
+resume f = case f of
+  Pure x -> Right x
+  Free x -> Left x
+  g -> case resumeGosub g of
+    Left l -> Left l
+    Right r -> resume r
 
 go :: forall f a. (Functor f) => (f (Free f a) -> Free f a) -> Free f a -> a
-go fn f = runFn6 goImpl resume isRight unsafeLeft unsafeRight fn f
+go fn f = case resume f of
+  Left l -> go fn (fn l)
+  Right r -> r
 
 foreign import goEffImpl
   "function goEffImpl(resume, isRight, fromLeft, fromRight, fn, value) {\