elm/compiler/Transform/Substitute.hs
2013-10-25 17:36:30 +02:00

43 lines
No EOL
1.5 KiB
Haskell

{-# OPTIONS_GHC -Wall #-}
module Transform.Substitute (subst) where
import Control.Arrow (second, (***))
import SourceSyntax.Expression
import SourceSyntax.Location
import qualified Data.Set as Set
import qualified Transform.SortDefinitions as SD
subst :: String -> Expr t v -> Expr t v -> Expr t v
subst old new expr =
let f (L s e) = L s (subst old new e) in
case expr of
Range e1 e2 -> Range (f e1) (f e2)
ExplicitList es -> ExplicitList (map f es)
Binop op e1 e2 -> Binop op (f e1) (f e2)
Lambda p e
| Set.member old (SD.boundVars p) -> expr
| otherwise -> Lambda p (f e)
App e1 e2 -> App (f e1) (f e2)
MultiIf ps -> MultiIf (map (f *** f) ps)
Let defs body
| anyShadow -> expr
| otherwise -> Let (map substDef defs) (f body)
where
anyShadow =
any (Set.member old . SD.boundVars) [ p | Def p _ <- defs ]
substDef def =
case def of
TypeAnnotation _ _ -> def
Def p e -> Def p (f e)
Var x -> if x == old then new else expr
Case e cases -> Case (f e) $ map (second f) cases
Data name es -> Data name (map f es)
Access e x -> Access (f e) x
Remove e x -> Remove (f e) x
Insert e x v -> Insert (f e) x (f v)
Modify r fs -> Modify (f r) (map (second f) fs)
Record fs -> Record (map (second f) fs)
Literal _ -> expr
Markdown uid md es -> Markdown uid md (map f es)