-- GeNeRaTeD fOr: ../../CBS/Funcons/Computations/Control flow/Normal/Choosing/if-then-else.aterm
{-# LANGUAGE OverloadedStrings #-}

module Funcons.Core.Computations.ControlFlow.Normal.Choosing.IfThenElse where

import Funcons.EDSL

entities = []

types = typeEnvFromList
    []

funcons = libFromList
    [("if-then-else",PartiallyStrictFuncon [Strict,NonStrict,NonStrict] stepIf_then_else)]

-- |
-- /if-then-else(B,X,Y)/ first evaluates /B/ .
--   Depending on whether the computed value is /true/ or /false/ ,
--   it then evaluates /X/ or /Y/ .
if_then_else_ fargs = FApp "if-then-else" (FTuple fargs)
stepIf_then_else fargs@[arg1,arg2,arg3] =
    evalRules [rewrite1,rewrite2] []
    where rewrite1 = do
            let env = emptyEnv
            env <- fsMatch fargs [PValue (PADT "true" []),PMetaVar "X",PWildCard] env
            rewriteTermTo (TVar "X") env
          rewrite2 = do
            let env = emptyEnv
            env <- fsMatch fargs [PValue (PADT "false" []),PWildCard,PMetaVar "Y"] env
            rewriteTermTo (TVar "Y") env
stepIf_then_else fargs = sortErr (FApp "if-then-else" (FTuple fargs)) "invalid number of arguments"