Future.hs

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

module Feldspar.Compiler.Imperative.FromCore.Future where

import Language.Syntactic

import Feldspar.Core.Types (Type)
import Feldspar.Core.Constructs.Future

import Feldspar.Compiler.Imperative.Frontend hiding (Type)
import qualified Feldspar.Compiler.Imperative.Frontend as Front
import Feldspar.Compiler.Imperative.FromCore.Interpretation
import Feldspar.Compiler.Imperative.Plugin.CollectFreeVars
import Feldspar.Transformation (transform, Result(..))

import Data.Map (elems)

instance Compile dom dom => Compile (FUTURE :|| Type) dom
  where
    compileExprSym = compileProgFresh

    compileProgSym (C' MkFuture) _ loc (p :* Nil) = do
        -- Task core:
        (_, Bl ds t)  <- confiscateBlock $ do
            p' <- compileExprVar p
            tellProg [iVarPut loc p']
        let b = Block ds t
        let vs = elems $ up $ transform Collect () () $ Front.fromInterface b
        funId  <- freshId
        let coreName = "task_core" ++ show funId
        tellDef [ProcDf coreName vs [] b]
        -- Task:
        let taskName = "task" ++ show funId
        let runTask = run coreName vs
        tellDef [ProcDf taskName [] [Front.Variable Void "params"] runTask]
        -- Spawn:
        tellProg [iVarInit loc]
        tellProg [spawn taskName vs]

    compileProgSym (C' Await) _ loc (a :* Nil) = do
        fut <- compileExprVar a -- compileExpr a
        tellProg [iVarGet loc fut]