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|
{-# LANGUAGE TemplateHaskell #-}
module Main where
import Control.Monad.Fix
import Language.Haskell.TH
import Control.Monad.State
-- Direct variant
$([d|
f1, f2 :: Integer -> [Integer]
f1 = \z -> z : f2 (succ z)
f2 = \z -> z : f1 (z * z)
|])
-- Using mfix.
-- This is a contrived example, but it fits into a single splice
$(fmap (\(x,x',y,y') ->
[ ValD (VarP x') (NormalB x) []
, ValD (VarP y') (NormalB y) []
]) $
mfix $ \ ~(_,x',_,y') -> do
x <- [| \z -> z : $(return $ VarE y') (succ z) |]
y <- [| \z -> z : $(return $ VarE x') (z * z) |]
x'' <- newName "g1"
y'' <- newName "g2"
return (x, x'', y, y'')
)
main :: IO ()
main = do
print $ take 11 $ f1 0
print $ take 11 $ g1 0
|
