38 lines
991 B
Haskell
38 lines
991 B
Haskell
{-# LANGUAGE BlockArguments #-}
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{-# LANGUAGE TypeFamilies #-}
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module Gyehoek.GenSym where
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import Numeric.Natural
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import Effectful.State.Dynamic
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import Effectful.Dispatch.Dynamic
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import Effectful
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import Data.String (IsString(fromString))
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import Data.Text (Text)
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import qualified Data.Text.Short as ST
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class Gen a where
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gen :: Natural -> a
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gen' :: Text -> Natural -> a
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data GenSym :: Effect where
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GenSym :: Gen a => GenSym m a
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GenSym' :: Gen a => Text -> GenSym m a
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type instance DispatchOf GenSym = Dynamic
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gensym :: forall a es. (Gen a, GenSym :> es) => Eff es a
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gensym = send GenSym
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gensym' :: forall a es. (Gen a, GenSym :> es) => Text -> Eff es a
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gensym' = send . GenSym'
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runGenSym :: Eff (GenSym : es) a -> Eff es a
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runGenSym = reinterpret (evalStateLocal (0 :: Natural)) \cases
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_ GenSym -> state \n -> (gen n, succ n)
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_ (GenSym' s) -> state \n -> (gen' s n, succ n)
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instance Gen Text where
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gen = fromString . ('x':) . show
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gen' s = (s <>) . fromString . show
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