import HsSyn
import TcHsSyn ( TypecheckedPat )
import DsHsSyn ( outPatType )
-import DsUtils ( EquationInfo(..), MatchResult(..), EqnSet, CanItFail(..),
- tidyLitPat
+import DsUtils ( EquationInfo(..), MatchResult(..), EqnSet,
+ CanItFail(..), tidyLitPat, tidyNPat,
)
import Id ( idType )
import DataCon ( DataCon, dataConTyCon, dataConArgTys,
dataConSourceArity, dataConFieldLabels )
import Name ( Name, mkLocalName, getOccName, isDataSymOcc, getName, mkVarOcc )
import Type ( splitAlgTyConApp, mkTyVarTys, splitTyConApp_maybe )
-import TysWiredIn ( nilDataCon, consDataCon,
- mkListTy, mkTupleTy, tupleCon
- )
+import TysPrim ( charPrimTy )
+import TysWiredIn
import PrelNames ( unboundKey )
import TyCon ( tyConDataCons, tupleTyConBoxity, isTupleTyCon )
import BasicTypes ( Boxity(..) )
| otherwise = x : insertNm nm p xs
simplify_pat pat@(LitPat lit lit_ty) = tidyLitPat lit pat
-simplify_pat pat@(NPat lit lit_ty hsexpr) = tidyLitPat lit pat
+
+-- unpack string patterns fully, so we can see when they overlap with
+-- each other, or even explicit lists of Chars.
+simplify_pat pat@(NPat (HsString s) _ _) =
+ foldr (\c pat -> ConPat consDataCon stringTy [] [] [mk_char_lit c,pat])
+ (ConPat nilDataCon stringTy [] [] []) (_UNPK_INT_ s)
+ where
+ mk_char_lit c = ConPat charDataCon charTy [] []
+ [LitPat (HsCharPrim c) charPrimTy]
+
+simplify_pat pat@(NPat lit lit_ty hsexpr) = tidyNPat lit lit_ty pat
simplify_pat (NPlusKPat id hslit ty hsexpr1 hsexpr2) =
WildPat ty