[project @ 1998-01-08 18:03:08 by simonm]

[ghc-hetmet.git] / ghc / compiler / deSugar / DsGRHSs.lhs

diff --git a/ghc/compiler/deSugar/DsGRHSs.lhs b/ghc/compiler/deSugar/DsGRHSs.lhs
index 63c41d7..40b625c 100644 (file)
--- a/ghc/compiler/deSugar/DsGRHSs.lhs
+++ b/ghc/compiler/deSugar/DsGRHSs.lhs
@@ -4,43 +4,32 @@
 \section[DsGRHSs]{Matching guarded right-hand-sides (GRHSs)}
 
 \begin{code}
-#include "HsVersions.h"
-
 module DsGRHSs ( dsGuarded, dsGRHSs ) where
 
-IMP_Ubiq()
-#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201
-IMPORT_DELOOPER(DsLoop)                -- break dsExpr/dsBinds-ish loop
-#else
+#include "HsVersions.h"
+
 import {-# SOURCE #-} DsExpr  ( dsExpr )
 import {-# SOURCE #-} DsBinds ( dsBinds )
-import {-# SOURCE #-} Match   ( match )
-#endif
+import {-# SOURCE #-} Match   ( matchExport )
 
 import HsSyn           ( GRHSsAndBinds(..), GRHS(..),
                          HsExpr(..), HsBinds, Stmt(..), 
                          HsLit, Match, Fixity, DoOrListComp, HsType, ArithSeqInfo
                         )
-import TcHsSyn         ( SYN_IE(TypecheckedGRHSsAndBinds), SYN_IE(TypecheckedGRHS),
-                         SYN_IE(TypecheckedPat), SYN_IE(TypecheckedHsBinds),
-                         SYN_IE(TypecheckedHsExpr), SYN_IE(TypecheckedStmt)
+import TcHsSyn         ( TypecheckedGRHSsAndBinds, TypecheckedGRHS,
+                         TypecheckedPat, TypecheckedHsBinds,
+                         TypecheckedHsExpr, TypecheckedStmt
                        )
-import CoreSyn         ( SYN_IE(CoreBinding), GenCoreBinding(..), SYN_IE(CoreExpr), mkCoLetsAny )
+import CoreSyn         ( CoreBinding, GenCoreBinding(..), CoreExpr, mkCoLetsAny )
 
 import DsMonad
 import DsUtils
-
-#if __GLASGOW_HASKELL__ < 200
-import Id              ( GenId )
-#endif
 import CoreUtils       ( coreExprType, mkCoreIfThenElse )
 import PrelVals                ( nON_EXHAUSTIVE_GUARDS_ERROR_ID )
-import Outputable      ( PprStyle(..) )
 import SrcLoc          ( SrcLoc{-instance-} )
-import Type             ( SYN_IE(Type) )
-import Unique          ( Unique, otherwiseIdKey )
-import UniqFM           ( Uniquable(..) )
-import Util            ( panic )
+import Type             ( Type )
+import Unique          ( Unique, otherwiseIdKey, trueDataConKey, Uniquable(..) )
+import Outputable
 \end{code}
 
 @dsGuarded@ is used for both @case@ expressions and pattern bindings.
@@ -60,7 +49,7 @@ dsGuarded :: TypecheckedGRHSsAndBinds
 
 dsGuarded (GRHSsAndBindsOut grhss binds err_ty)
   = dsBinds False{-don't auto scc-} binds       `thenDs` \ core_binds ->
-    dsGRHSs err_ty PatBindMatch [] grhss       `thenDs` \ (MatchResult can_it_fail _ core_grhss_fn _) ->
+    dsGRHSs err_ty PatBindMatch [] grhss       `thenDs` \ (MatchResult can_it_fail _ core_grhss_fn) ->
     case can_it_fail of
        CantFail -> returnDs (mkCoLetsAny core_binds (core_grhss_fn (panic "It can't fail")))
        CanFail  -> mkErrorAppDs nON_EXHAUSTIVE_GUARDS_ERROR_ID err_ty "" `thenDs` \ error_expr ->
@@ -91,21 +80,13 @@ dsGRHSs ty kind pats (grhs:grhss)
     dsGRHSs ty kind pats grhss `thenDs` \ match_result2 ->
     combineGRHSMatchResults match_result1 match_result2
 
-dsGRHS ty kind pats (OtherwiseGRHS expr locn)
-  = putSrcLocDs locn $
-    dsExpr expr        `thenDs` \ core_expr ->
-    let
-       expr_fn = \ ignore -> core_expr
-    in
-    returnDs (MatchResult CantFail ty expr_fn (DsMatchContext kind pats locn))
-
 dsGRHS ty kind pats (GRHS guard expr locn)
   = putSrcLocDs locn $
     dsExpr expr        `thenDs` \ core_expr ->
     let
        expr_fn = \ ignore -> core_expr
     in
-    matchGuard guard (MatchResult CantFail ty expr_fn (DsMatchContext kind pats locn))
+    matchGuard guard (DsMatchContext kind pats locn) (MatchResult CantFail ty expr_fn) 
 \end{code}
 
 
@@ -119,33 +100,37 @@ dsGRHS ty kind pats (GRHS guard expr locn)
 
 \begin{code}
 matchGuard :: [TypecheckedStmt]        -- Guard
+           -> DsMatchContext            -- Context
           -> MatchResult               -- What to do if the guard succeeds
           -> DsM MatchResult
 
-matchGuard [] body_result = returnDs body_result
+matchGuard [] ctx body_result = returnDs body_result
 
        -- Turn an "otherwise" guard is a no-op
-matchGuard (GuardStmt (HsVar v) _ : stmts) body_result
-  | uniqueOf v == otherwiseIdKey
-  = matchGuard stmts body_result
-
-matchGuard (GuardStmt expr _ : stmts) body_result
-  = matchGuard stmts body_result       `thenDs` \ (MatchResult _ ty body_fn cxt) ->
+matchGuard (GuardStmt (HsVar v) _ : stmts) ctx body_result
+  |  uniq == otherwiseIdKey
+  || uniq == trueDataConKey
+  = matchGuard stmts ctx body_result
+  where
+    uniq = uniqueOf v
+
+matchGuard (GuardStmt expr _ : stmts) ctx body_result
+  = matchGuard stmts ctx body_result   `thenDs` \ (MatchResult _ ty body_fn) ->
     dsExpr expr                                `thenDs` \ core_expr ->
     let
        expr_fn = \ fail -> mkCoreIfThenElse core_expr (body_fn fail) fail
     in
-    returnDs (MatchResult CanFail ty expr_fn cxt)
+    returnDs (MatchResult CanFail ty expr_fn)
 
-matchGuard (LetStmt binds : stmts) body_result
-  = matchGuard stmts body_result         `thenDs` \ match_result ->
+matchGuard (LetStmt binds : stmts) ctx body_result
+  = matchGuard stmts ctx body_result     `thenDs` \ match_result ->
     dsBinds False{-don't auto scc-} binds `thenDs` \ core_binds ->
     returnDs (mkCoLetsMatchResult core_binds match_result)
 
-matchGuard (BindStmt pat rhs _ : stmts) body_result
-  = matchGuard stmts body_result                       `thenDs` \ match_result ->
+matchGuard (BindStmt pat rhs _ : stmts) ctx body_result
+  = matchGuard stmts ctx body_result                   `thenDs` \ match_result ->
     dsExpr rhs                                         `thenDs` \ core_rhs ->
     newSysLocalDs (coreExprType core_rhs)              `thenDs` \ scrut_var ->
-    match [scrut_var] [EqnInfo [pat] match_result] []  `thenDs` \ match_result' ->
+    matchExport [scrut_var] [EqnInfo 1 ctx [pat] match_result]         `thenDs` \ match_result' ->
     returnDs (mkCoLetsMatchResult [NonRec scrut_var core_rhs] match_result')
 \end{code}