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[project @ 2001-03-24 14:58:04 by simonmar]
[ghc-hetmet.git]
/
ghc
/
compiler
/
deSugar
/
DsGRHSs.lhs
diff --git
a/ghc/compiler/deSugar/DsGRHSs.lhs
b/ghc/compiler/deSugar/DsGRHSs.lhs
index
31e4428
..
918ec65
100644
(file)
--- a/
ghc/compiler/deSugar/DsGRHSs.lhs
+++ b/
ghc/compiler/deSugar/DsGRHSs.lhs
@@
-11,7
+11,7
@@
module DsGRHSs ( dsGuarded, dsGRHSs ) where
import {-# SOURCE #-} DsExpr ( dsExpr, dsLet )
import {-# SOURCE #-} Match ( matchSinglePat )
import {-# SOURCE #-} DsExpr ( dsExpr, dsLet )
import {-# SOURCE #-} Match ( matchSinglePat )
-import HsSyn ( Stmt(..), HsExpr(..), GRHSs(..), GRHS(..) )
+import HsSyn ( Stmt(..), HsExpr(..), GRHSs(..), GRHS(..), HsMatchContext(..) )
import TcHsSyn ( TypecheckedGRHSs, TypecheckedPat, TypecheckedStmt )
import CoreSyn ( CoreExpr )
import Type ( Type )
import TcHsSyn ( TypecheckedGRHSs, TypecheckedPat, TypecheckedStmt )
import CoreSyn ( CoreExpr )
import Type ( Type )
@@
-19,7
+19,7
@@
import Type ( Type )
import DsMonad
import DsUtils
import PrelInfo ( nON_EXHAUSTIVE_GUARDS_ERROR_ID )
import DsMonad
import DsUtils
import PrelInfo ( nON_EXHAUSTIVE_GUARDS_ERROR_ID )
-import Unique ( otherwiseIdKey, trueDataConKey, hasKey )
+import PrelNames ( otherwiseIdKey, trueDataConKey, hasKey )
\end{code}
@dsGuarded@ is used for both @case@ expressions and pattern bindings.
\end{code}
@dsGuarded@ is used for both @case@ expressions and pattern bindings.
@@
-37,7
+37,7
@@
necessary. The type argument gives the type of the @ei@.
dsGuarded :: TypecheckedGRHSs -> DsM CoreExpr
dsGuarded grhss
dsGuarded :: TypecheckedGRHSs -> DsM CoreExpr
dsGuarded grhss
- = dsGRHSs PatBindMatch [] grhss `thenDs` \ (err_ty, match_result) ->
+ = dsGRHSs PatBindRhs [] grhss `thenDs` \ (err_ty, match_result) ->
mkErrorAppDs nON_EXHAUSTIVE_GUARDS_ERROR_ID err_ty "" `thenDs` \ error_expr ->
extractMatchResult match_result error_expr
\end{code}
mkErrorAppDs nON_EXHAUSTIVE_GUARDS_ERROR_ID err_ty "" `thenDs` \ error_expr ->
extractMatchResult match_result error_expr
\end{code}
@@
-45,7
+45,7
@@
dsGuarded grhss
In contrast, @dsGRHSs@ produces a @MatchResult@.
\begin{code}
In contrast, @dsGRHSs@ produces a @MatchResult@.
\begin{code}
-dsGRHSs :: DsMatchKind -> [TypecheckedPat] -- These are to build a MatchContext from
+dsGRHSs :: HsMatchContext -> [TypecheckedPat] -- These are to build a MatchContext from
-> TypecheckedGRHSs -- Guarded RHSs
-> DsM (Type, MatchResult)
-> TypecheckedGRHSs -- Guarded RHSs
-> DsM (Type, MatchResult)
@@
-74,17
+74,21
@@
matchGuard :: [TypecheckedStmt] -- Guard
-> DsMatchContext -- Context
-> DsM MatchResult
-> DsMatchContext -- Context
-> DsM MatchResult
-matchGuard (ExprStmt expr locn : should_be_null) ctx
+-- See comments with HsExpr.HsStmt re what an ExprStmt means
+-- Here we must be in a guard context (not do-expression, nor list-comp)
+
+matchGuard [ExprStmt expr locn] ctx
= putSrcLocDs locn (dsExpr expr) `thenDs` \ core_expr ->
returnDs (cantFailMatchResult core_expr)
= putSrcLocDs locn (dsExpr expr) `thenDs` \ core_expr ->
returnDs (cantFailMatchResult core_expr)
+ -- Other ExprStmts must be guards
-- Turn an "otherwise" guard is a no-op
-- Turn an "otherwise" guard is a no-op
-matchGuard (GuardStmt (HsVar v) _ : stmts) ctx
+matchGuard (ExprStmt (HsVar v) _ : stmts) ctx
| v `hasKey` otherwiseIdKey
|| v `hasKey` trueDataConKey
= matchGuard stmts ctx
| v `hasKey` otherwiseIdKey
|| v `hasKey` trueDataConKey
= matchGuard stmts ctx
-matchGuard (GuardStmt expr locn : stmts) ctx
+matchGuard (ExprStmt expr locn : stmts) ctx
= matchGuard stmts ctx `thenDs` \ match_result ->
putSrcLocDs locn (dsExpr expr) `thenDs` \ pred_expr ->
returnDs (mkGuardedMatchResult pred_expr match_result)
= matchGuard stmts ctx `thenDs` \ match_result ->
putSrcLocDs locn (dsExpr expr) `thenDs` \ pred_expr ->
returnDs (mkGuardedMatchResult pred_expr match_result)