Binding.hs

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{-# LANGUAGE UndecidableInstances #-}

module Feldspar.Compiler.Imperative.FromCore.Binding where

import Control.Monad.RWS

import Language.Syntactic

import Feldspar.Core.Types
import Feldspar.Core.Interpretation
import Feldspar.Core.Constructs.Binding
import qualified Feldspar.Core.Constructs.Binding as Core

import Feldspar.Compiler.Imperative.Frontend
import Feldspar.Compiler.Imperative.FromCore.Interpretation



instance Compile (Core.Variable TypeCtx) dom
  where
    compileExprSym (Core.Variable v) info Nil = do
        env <- ask
        case lookup v (alias env) of
          Nothing -> return $ Var (compileTypeRep (infoType info) (infoSize info)) ("v" ++ show v)
          Just e  -> return e

instance Compile (Lambda TypeCtx) dom
  where
    compileProgSym = error "Can only compile top-level Lambda"

instance (Compile dom dom, Lambda TypeCtx :<: dom) => Compile (Let TypeCtx TypeCtx) dom
  where
    compileProgSym Let _ loc (a :* (lam :$ body) :* Nil)
        | Just (info, Lambda v) <- prjDecorCtx typeCtx lam
        = do
            let ta = argType $ infoType info
            let sa = defaultSize ta
            let var = mkVar (compileTypeRep ta sa) v
            compileProg var a
            withDecl var $ compileProg loc body

    compileExprSym Let _ (a :* (lam :$ body) :* Nil)
        | Just (info, Lambda v) <- prjDecorCtx typeCtx lam
        = do
            let ta = argType $ infoType info
            let sa = defaultSize ta
            let var = mkVar (compileTypeRep ta sa) v
            compileProg var a
            withDecl var $ compileExpr body