%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[DsGRHSs]{Matching guarded right-hand-sides (GRHSs)}
+
+Matching guarded right-hand-sides (GRHSs)
\begin{code}
module DsGRHSs ( dsGuarded, dsGRHSs ) where
import {-# SOURCE #-} DsExpr ( dsLExpr, dsLocalBinds )
import {-# SOURCE #-} Match ( matchSinglePat )
-import HsSyn ( Stmt(..), HsExpr(..), GRHSs(..), GRHS(..),
- LHsExpr, HsMatchContext(..), Pat(..) )
-import CoreSyn ( CoreExpr )
-import Var ( Id )
-import Type ( Type )
+import HsSyn
+import CoreSyn
+import Var
+import Type
import DsMonad
import DsUtils
-import Unique ( Uniquable(..) )
-import PrelInfo ( nON_EXHAUSTIVE_GUARDS_ERROR_ID )
-import TysWiredIn ( trueDataConId )
-import PrelNames ( otherwiseIdKey, hasKey )
-import Name ( Name )
-import SrcLoc ( unLoc, Located(..) )
+import PrelInfo
+import TysWiredIn
+import PrelNames
+import Name
+import SrcLoc
+
\end{code}
@dsGuarded@ is used for both @case@ expressions and pattern bindings.
-> GRHSs Id -- Guarded RHSs
-> Type -- Type of RHS
-> DsM MatchResult
-
-dsGRHSs hs_ctx pats (GRHSs grhss binds) rhs_ty
- = mappM (dsGRHS hs_ctx pats rhs_ty) grhss `thenDs` \ match_results ->
+dsGRHSs hs_ctx pats grhssa@(GRHSs grhss binds) rhs_ty = do
+ match_results <- mappM (dsGRHS hs_ctx pats rhs_ty) grhss
let
match_result1 = foldr1 combineMatchResults match_results
- match_result2 = adjustMatchResultDs (dsLocalBinds binds) match_result1
+ match_result2 = adjustMatchResultDs
+ (\e -> dsLocalBinds binds e)
+ match_result1
-- NB: nested dsLet inside matchResult
- in
+ --
returnDs match_result2
dsGRHS hs_ctx pats rhs_ty (L loc (GRHS guards rhs))
-- you don't get a "non-exhaustive eqns" message when the guards
-- finish in "otherwise".
-- NB: The success of this clause depends on the typechecker not
- -- wrapping the 'otherwise' in empty HsTyApp or HsCoerce constructors
+ -- wrapping the 'otherwise' in empty HsTyApp or HsWrap constructors
-- If it does, you'll get bogus overlap warnings
matchGuards (ExprStmt (L _ (HsVar v)) _ _ : stmts) ctx rhs rhs_ty
| v `hasKey` otherwiseIdKey