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Merged
merged 4 commits into from
Nov 2, 2014
Merged

Avoid ffi #16

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119d5c4
Implement `go` directly
garyb Nov 2, 2014
ef06b4d
Implement `resume` directly
garyb Nov 2, 2014
08112da
Implement `goEff` directly
garyb Nov 2, 2014
f2cbbe5
Revert "Implement `goEff` directly"
garyb Nov 2, 2014
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6 changes: 3 additions & 3 deletions MODULE.md
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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

Expand Down Expand Up @@ -181,7 +181,7 @@

### Types

type Trampoline = Free Lazy
type Trampoline = Free Lazy


### Values
Expand Down
52 changes: 9 additions & 43 deletions src/Control/Monad/Free.purs
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Expand Up @@ -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) {\
Expand Down