Eq.hs

{-# LANGUAGE GADTs #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}

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-- | Implementation of Equality constructs

module Feldspar.Core.Constructs.Eq
where

import Language.Syntactic
import Language.Syntactic.Constructs.Binding

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

-- | Equality constructs
data EQ a
  where
    Equal    :: (Type a, Eq a) => EQ (a :-> a :-> Full Bool)
    NotEqual :: (Type a, Eq a) => EQ (a :-> a :-> Full Bool)

instance Semantic EQ
  where
    semantics Equal    = Sem "(==)" (==)
    semantics NotEqual = Sem "(/=)" (/=)

semanticInstances ''EQ

instance EvalBind EQ where evalBindSym = evalBindSymDefault

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

instance Sharable EQ

instance Monotonic EQ

instance SizeProp (EQ :|| Type)
  where sizeProp a@(C' _) = sizePropDefault a

instance ((EQ :|| Type) :<: dom, OptimizeSuper dom) => Optimize (EQ :|| Type) dom
  where
    constructFeatOpt _ (C' Equal) (a :* b :* Nil)
        | alphaEq a b
        = return $ literalDecor True

    constructFeatOpt _ (C' Equal) (a :* b :* Nil)
        | RangeSet ra <- infoRange (getInfo a)
        , RangeSet rb <- infoRange (getInfo b)
        , ra `disjoint` rb
        = return $ literalDecor False

    constructFeatOpt _ (C' NotEqual) (a :* b :* Nil)
        | alphaEq a b
        = return $ literalDecor False

    constructFeatOpt _ (C' NotEqual) (a :* b :* Nil)
        | RangeSet ra <- infoRange (getInfo a)
        , RangeSet rb <- infoRange (getInfo b)
        , ra `disjoint` rb
        = return $ literalDecor True

    constructFeatOpt opts a args = constructFeatUnOpt opts a args

    constructFeatUnOpt opts x@(C' _) = constructFeatUnOptDefault opts x