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{-# LANGUAGE UndecidableInstances #-}

module Feldspar.Core.Constructs.Fractional
    ( FRACTIONAL (..)
    ) where



import Language.Syntactic
import Language.Syntactic.Interpretation.Semantics
import Language.Syntactic.Constructs.Binding

import Feldspar.Core.Types
import Feldspar.Core.Interpretation

data FRACTIONAL a
  where
    DivFrac :: (Type a, Fractional a) => FRACTIONAL (a :-> a :-> Full a)

instance WitnessCons FRACTIONAL
  where
    witnessCons DivFrac = ConsWit

instance WitnessSat FRACTIONAL
  where
    type SatContext FRACTIONAL = TypeCtx
    witnessSat DivFrac = SatWit

instance MaybeWitnessSat TypeCtx FRACTIONAL
  where
    maybeWitnessSat = maybeWitnessSatDefault

instance Semantic FRACTIONAL
  where
    semantics DivFrac = Sem "(/)" (/)

instance ExprEq   FRACTIONAL where exprEq = exprEqSem; exprHash = exprHashSem
instance Render   FRACTIONAL where renderPart = renderPartSem
instance ToTree   FRACTIONAL
instance Eval     FRACTIONAL where evaluate = evaluateSem
instance EvalBind FRACTIONAL where evalBindSym = evalBindSymDefault
instance SizeProp FRACTIONAL where sizeProp = sizePropDefault
instance Sharable FRACTIONAL

instance AlphaEq dom dom dom env => AlphaEq FRACTIONAL FRACTIONAL dom env
  where
    alphaEqSym = alphaEqSymDefault

instance (FRACTIONAL :<: dom, Optimize dom dom) => Optimize FRACTIONAL dom
  where
    constructFeatOpt DivFrac (a :* b :* Nil)
        | Just 1 <- viewLiteral b = return a

    constructFeatOpt a args = constructFeatUnOpt a args

    constructFeatUnOpt = constructFeatUnOptDefault