[project @ 1998-03-19 23:54:49 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcGRHSs.lhs

diff --git a/ghc/compiler/typecheck/TcGRHSs.lhs b/ghc/compiler/typecheck/TcGRHSs.lhs
index edc2869..d19715c 100644 (file)
--- a/ghc/compiler/typecheck/TcGRHSs.lhs
+++ b/ghc/compiler/typecheck/TcGRHSs.lhs
@@ -6,49 +6,42 @@
 \begin{code}
 module TcGRHSs ( tcGRHSsAndBinds ) where
 
-import Ubiq{-uitous-}
-import TcLoop -- for paranoia checking
+#include "HsVersions.h"
 
-import HsSyn           ( GRHSsAndBinds(..), GRHS(..),
-                         HsExpr, HsBinds(..), InPat, OutPat, Bind, Sig, Fake )
-import RnHsSyn         ( RenamedGRHSsAndBinds(..), RenamedGRHS(..) )
-import TcHsSyn         ( TcGRHSsAndBinds(..), TcGRHS(..), TcIdOcc(..) )
+import HsSyn           ( HsBinds(..), GRHSsAndBinds(..), GRHS(..), DoOrListComp(..) )
+import RnHsSyn         ( RenamedGRHSsAndBinds, RenamedGRHS )
+import TcHsSyn         ( TcGRHSsAndBinds, TcGRHS )
 
-import TcMonad         hiding ( rnMtoTcM )
-import Inst            ( Inst, LIE(..), plusLIE )
+import TcMonad
+import Inst            ( Inst, LIE, plusLIE )
 import TcBinds         ( tcBindsAndThen )
-import TcExpr          ( tcExpr )
-import TcType          ( TcType(..) ) 
-import Unify           ( unifyTauTy )
-
-import TysWiredIn      ( boolTy )
+import TcExpr          ( tcExpr, tcStmt )
+import TcType          ( TcType ) 
 \end{code}
 
 \begin{code}
-tcGRHSs :: [RenamedGRHS] -> TcM s ([TcGRHS s], LIE s, TcType s)
-
-tcGRHSs [grhs]
-  = tcGRHS grhs                `thenTc` \ (grhs', lie, ty) ->
-    returnTc ([grhs'], lie, ty)
-
-tcGRHSs (grhs:grhss)
-  = tcGRHS  grhs       `thenTc` \ (grhs',  lie1, ty1) ->
-    tcGRHSs grhss      `thenTc` \ (grhss', lie2, ty2) ->
-    unifyTauTy ty1 ty2 `thenTc_`
-    returnTc (grhs' : grhss', lie1 `plusLIE` lie2, ty1)
+tcGRHSs :: TcType s -> [RenamedGRHS] -> TcM s ([TcGRHS s], LIE s)
 
+tcGRHSs expected_ty [grhs]
+  = tcGRHS expected_ty grhs            `thenTc` \ (grhs', lie) ->
+    returnTc ([grhs'], lie)
 
-tcGRHS (OtherwiseGRHS expr locn)
-  = tcAddSrcLoc locn    $
-    tcExpr expr        `thenTc` \ (expr, lie, ty) ->
-    returnTc (OtherwiseGRHS expr locn, lie, ty)
+tcGRHSs expected_ty (grhs:grhss)
+  = tcGRHS  expected_ty grhs   `thenTc` \ (grhs',  lie1) ->
+    tcGRHSs expected_ty grhss  `thenTc` \ (grhss', lie2) ->
+    returnTc (grhs' : grhss', lie1 `plusLIE` lie2)
 
-tcGRHS (GRHS guard expr locn)
+tcGRHS expected_ty (GRHS guard expr locn)
   = tcAddSrcLoc locn           $
-    tcExpr guard               `thenTc` \ (guard2, guard_lie, guard_ty) ->
-    unifyTauTy boolTy guard_ty `thenTc_`
-    tcExpr expr                        `thenTc` \ (expr2, expr_lie, expr_ty) ->
-    returnTc (GRHS guard2 expr2 locn, plusLIE guard_lie expr_lie, expr_ty)
+    tcStmts guard              `thenTc` \ ((guard', expr'), lie) ->
+    returnTc (GRHS guard' expr' locn, lie)
+  where
+    tcStmts []          = tcExpr expr expected_ty        `thenTc`    \ (expr2, expr_lie) ->
+                          returnTc (([], expr2), expr_lie)
+    tcStmts (stmt:stmts) = tcStmt tcExpr Guard (\x->x) combine stmt $
+                          tcStmts stmts
+
+    combine stmt _ (stmts, expr) = (stmt:stmts, expr)
 \end{code}
 
 
@@ -56,16 +49,20 @@ tcGRHS (GRHS guard expr locn)
 pieces.
 
 \begin{code}
-tcGRHSsAndBinds :: RenamedGRHSsAndBinds
-               -> TcM s (TcGRHSsAndBinds s, LIE s, TcType s)
+tcGRHSsAndBinds :: TcType s                    -- Expected type of RHSs
+               -> RenamedGRHSsAndBinds
+               -> TcM s (TcGRHSsAndBinds s, LIE s)
+
+-- Shortcut for common case
+tcGRHSsAndBinds expected_ty (GRHSsAndBindsIn grhss EmptyBinds) 
+  = tcGRHSs expected_ty grhss         `thenTc` \ (grhss', lie) ->
+    returnTc (GRHSsAndBindsOut grhss' EmptyBinds expected_ty, lie)
 
-tcGRHSsAndBinds (GRHSsAndBindsIn grhss binds)
+tcGRHSsAndBinds expected_ty (GRHSsAndBindsIn grhss binds)
   = tcBindsAndThen
         combiner binds
-        (tcGRHSs grhss         `thenTc` \ (grhss', lie, ty) ->
-         returnTc (GRHSsAndBindsOut grhss' EmptyBinds ty, lie, ty)
-        )
+        (tcGRHSs expected_ty grhss)
   where
-    combiner binds1 (GRHSsAndBindsOut grhss binds2 ty) 
-       = GRHSsAndBindsOut grhss (binds1 `ThenBinds` binds2) ty
+    combiner is_rec binds grhss
+       = GRHSsAndBindsOut grhss (MonoBind binds [] is_rec) expected_ty
 \end{code}