Created
April 6, 2014 18:45
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Self optimizing Par Arrow
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{-# LANGUAGE Arrows, GADTs #-} | |
data Par a b where | |
Pure :: (a -> b) -> Par a b | |
Seq :: Par a b -> Par b c -> Par a c | |
Par :: (a -> (a1, a2)) -> Par a1 b1 -> Par a2 b2 -> ((b1, b2) -> b) -> Par a b | |
instance Category Par where | |
id = Pure id | |
Pure p . Pure q = Pure (p . q) | |
Pure p . Seq f g = Seq f (Pure p . g) | |
Pure p . Par l h k r = Par l h k (p . r) | |
Seq f g . Pure h = Seq (f . Pure h) g | |
Seq f g . Seq h k = Seq (k . h) (g . f) | |
Seq f g . Par l h k r = Seq (Par l h k r) (g . f) | |
Par l h k r . Pure p = Par (l . p) h k r | |
Par l h k r . Seq f g = Seq (g . f) (Par l h k r) | |
Par l h k r . Par s f g t = | |
let p1f x = fst . l $ t (x, undefined) | |
p2f x = snd . l $ t (undefined, x) | |
pp1 = h . arr p1f . f | |
pp2 = k . arr p2f . g | |
in Par s pp1 pp2 r | |
data Trace | |
= TPure | |
| Trace :>: Trace | |
| Trace :|: Trace | |
deriving Show | |
trace :: Par a b -> Trace | |
trace (Pure _) = TPure | |
trace (Seq f g) = trace f :>: trace g | |
trace (Par _ f g _) = trace f :|: trace g | |
a1 :: (Arrow arr, Num a) => arr a a | |
a1 = proc x -> do | |
a <- arr (*2) -< x | |
b <- arr (+3) -< x | |
c <- arr (^2) -< a | |
returnA -< a * b + c | |
main = print $ trace a1 |
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