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 qualified Data.Set as Set

7import SourceSyntax.Annotation

8import SourceSyntax.Expression

9import qualified SourceSyntax.Pattern as Pattern

10import qualified SourceSyntax.Variable as V

12subst :: String -> Expr' -> Expr' -> Expr'

13subst old new expr =

14 let f (A a e) = A a (subst old new e) in

15 case expr of

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

17 ExplicitList es -> ExplicitList (map f es)

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

19 Lambda p e

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

21 | otherwise -> Lambda p (f e)

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

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

25 Let defs body

26 | anyShadow -> expr

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

28 where

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

30 anyShadow =

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

33 Var (V.Raw x) -> if x == old then new else expr

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

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

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

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

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

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

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

41 Literal _ -> expr

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

43 PortIn name st -> PortIn name st

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