compiler/Transform/Substitute.hs · elk

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elk/compiler/Transform/Substitute.hs

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1{-# OPTIONS_GHC -Wall #-}

2module Transform.Substitute (subst) where

4import Control.Arrow (second, (***))

5import SourceSyntax.Expression

6import SourceSyntax.Location

7import qualified SourceSyntax.Pattern as Pattern

8import qualified Data.Set as Set

10subst :: String -> Expr -> Expr -> Expr

11subst old new expr =

12 let f (L s e) = L s (subst old new e) in

13 case expr of

14 Range e1 e2 -> Range (f e1) (f e2)

15 ExplicitList es -> ExplicitList (map f es)

16 Binop op e1 e2 -> Binop op (f e1) (f e2)

17 Lambda p e

18 | Set.member old (Pattern.boundVars p) -> expr

19 | otherwise -> Lambda p (f e)

20 App e1 e2 -> App (f e1) (f e2)

21 MultiIf ps -> MultiIf (map (f *** f) ps)

23 Let defs body

24 | anyShadow -> expr

25 | otherwise -> Let (map substDef defs) (f body)

26 where

27 substDef (Definition p e t) = Definition p (f e) t

28 anyShadow =

29 any (Set.member old . Pattern.boundVars) [ p | Definition p _ _ <- defs ]

31 Var x -> if x == old then new else expr

32 Case e cases -> Case (f e) $ map (second f) cases

33 Data name es -> Data name (map f es)

34 Access e x -> Access (f e) x

35 Remove e x -> Remove (f e) x

36 Insert e x v -> Insert (f e) x (f v)

37 Modify r fs -> Modify (f r) (map (second f) fs)

38 Record fs -> Record (map (second f) fs)

39 Literal _ -> expr

40 Markdown uid md es -> Markdown uid md (map f es)

41 PortIn name st -> PortIn name st

42 PortOut name st signal -> PortOut name st (f signal)