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{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleContexts #-}

module Feldspar.Core.Frontend.Switch where

import Prelude (($),foldr)

import Language.Syntactic (resugar,Syntactic(..))

import Feldspar.Core.Frontend.Eq (Eq((==)))
import Feldspar.Core.Frontend.Condition ((?))
import Feldspar.Core.Constructs
import Feldspar.Core.Constructs.Switch

-- | Select between the cases based on the value of the scrutinee.
select :: (Eq a, Syntax b) => Data a -> [(Data a, b)] -> b -> b
select s cs def = foldr (\(c,a) b -> c == s ? a $ b) def cs

{-# DEPRECATED select "select will generate a tree of if-statements. Use switch instead" #-}

-- | Select between the cases based on the value of the scrutinee.
-- If no match is found return the first argument
switch :: (Eq (Internal a), Syntax a, Syntax b)
       => b -> [(a, b)] -> a -> b
switch def [] _ = def
switch def cs s = let s' = resugar s
                  in sugarSymF Switch (foldr (\(c,a) b -> resugar c == s' ? a $ b) def cs)