44 lines
713 B
Haskell
44 lines
713 B
Haskell
{-# LANGUAGE DeriveFunctor #-}
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module Langdsl where
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import Control.Monad
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import Parser
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data Toy a next = Output a next | Bell next | Done
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deriving Functor
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newtype Fix f = Fix (f (Fix f))
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type Toy2 a = Fix (Toy a)
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data Free f r = Free (f (Free f r)) | Pure r
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deriving Functor
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instance Functor f => Monad (Free f) where
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return = Pure
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(Pure r) >>= f = f r
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(Free a) >>= f = Free $ (fmap (>>= f) a)
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instance Functor f => Applicative (Free f) where
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pure = Pure
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(<*>) = ap
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liftF x = Free (fmap Pure x)
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output x = liftF (Output x ())
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bell = liftF (Bell ())
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done = liftF Done
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sub :: Free (Toy Char) ()
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sub = do
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output 'x'
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bell
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prog = do
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sub
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output 'A'
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done
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toyParser :: Parser (Toy c)
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