Massive patch for the first months work adding System FC to GHC #34

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

diff --git a/compiler/typecheck/TcArrows.lhs b/compiler/typecheck/TcArrows.lhs
index 3bfa9b4..b4afcaf 100644 (file)
--- a/compiler/typecheck/TcArrows.lhs
+++ b/compiler/typecheck/TcArrows.lhs
@@ -22,7 +22,8 @@ import TcType ( TcType, TcTauType, BoxyRhoType, mkFunTys, mkTyConApp,
 import TcMType ( newFlexiTyVarTy, tcInstSkolTyVars, zonkTcType )
 import TcBinds ( tcLocalBinds )
 import TcSimplify ( tcSimplifyCheck )
-import TcPat   ( tcPat, tcPats, PatCtxt(..) )
+import TcGadt  ( Refinement, emptyRefinement, refineResType )
+import TcPat   ( tcLamPat, tcLamPats )
 import TcUnify ( checkSigTyVarsWrt, boxySplitAppTy )
 import TcRnMonad
 import Inst    ( tcSyntaxName )
@@ -32,7 +33,7 @@ import VarSet
 import TysPrim ( alphaTyVar )
 import Type    ( Kind, mkArrowKinds, liftedTypeKind, openTypeKind, tyVarsOfTypes )
 
-import SrcLoc  ( Located(..) )
+import SrcLoc  ( Located(..), noLoc, unLoc )
 import Outputable
 import Util    ( lengthAtLeast )
 
@@ -54,8 +55,8 @@ tcProc pat cmd exp_ty
     do { (exp_ty1, res_ty) <- boxySplitAppTy exp_ty 
        ; (arr_ty, arg_ty)  <- boxySplitAppTy exp_ty1
        ; let cmd_env = CmdEnv { cmd_arr = arr_ty }
-       ; (pat', cmd') <- tcPat LamPat pat arg_ty res_ty $ \ res_ty' ->
-                         tcCmdTop cmd_env cmd ([], res_ty')
+       ; (pat', cmd') <- tcLamPat pat arg_ty (emptyRefinement, res_ty) $
+                         tcCmdTop cmd_env cmd []
        ; return (pat', cmd') }
 \end{code}
 
@@ -79,20 +80,29 @@ mkCmdArrTy env t1 t2 = mkAppTys (cmd_arr env) [t1, t2]
 ---------------------------------------
 tcCmdTop :: CmdEnv 
          -> LHsCmdTop Name
-         -> (CmdStack, TcTauType)      -- Expected result type; always a monotype
+         -> CmdStack
+        -> (Refinement, TcTauType)     -- Expected result type; always a monotype
                                        -- We know exactly how many cmd args are expected,
                                        -- albeit perhaps not their types; so we can pass 
                                        -- in a CmdStack
         -> TcM (LHsCmdTop TcId)
 
-tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) (cmd_stk, res_ty)
+tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) cmd_stk reft_res_ty@(_,res_ty)
   = setSrcSpan loc $
-    do { cmd'   <- tcCmd env cmd (cmd_stk, res_ty)
+    do { cmd'   <- tcGuardedCmd env cmd cmd_stk reft_res_ty
        ; names' <- mapM (tcSyntaxName ProcOrigin (cmd_arr env)) names
        ; return (L loc $ HsCmdTop cmd' cmd_stk res_ty names') }
 
 
 ----------------------------------------
+tcGuardedCmd :: CmdEnv -> LHsExpr Name -> CmdStack
+            -> (Refinement, TcTauType) -> TcM (LHsExpr TcId)
+-- A wrapper that deals with the refinement (if any)
+tcGuardedCmd env expr stk (reft, res_ty)
+  = do { let (co, res_ty') = refineResType reft res_ty
+       ; body <- tcCmd env expr (stk, res_ty')
+       ; return (mkLHsCoerce co body) }
+
 tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
        -- The main recursive function
 tcCmd env (L loc expr) res_ty
@@ -120,7 +130,7 @@ tc_cmd env in_cmd@(HsCase scrut matches) (stk, res_ty)
   where
     match_ctxt = MC { mc_what = CaseAlt,
                       mc_body = mc_body }
-    mc_body body res_ty' = tcCmd env body (stk, res_ty')
+    mc_body body res_ty' = tcGuardedCmd env body stk res_ty'
 
 tc_cmd env (HsIf pred b1 b2) res_ty
   = do         { pred' <- tcMonoExpr pred boolTy
@@ -169,7 +179,6 @@ tc_cmd env cmd@(HsApp fun arg) (cmd_stk, res_ty)
 -------------------------------------------
 --             Lambda
 
--- gaw 2004
 tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig grhss))] _))
        (cmd_stk, res_ty)
   = addErrCtxt (matchCtxt match_ctxt match)    $
@@ -180,7 +189,7 @@ tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig g
 
                -- Check the patterns, and the GRHSs inside
        ; (pats', grhss') <- setSrcSpan mtch_loc                $
-                            tcPats LamPat pats cmd_stk res_ty  $
+                            tcLamPats pats cmd_stk res_ty      $
                             tc_grhss grhss
 
        ; let match' = L mtch_loc (Match pats' Nothing grhss')
@@ -199,9 +208,8 @@ tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig g
             ; return (GRHSs grhss' binds') }
 
     tc_grhs res_ty (GRHS guards body)
-       = do { (guards', rhs') <- tcStmts pg_ctxt tcGuardStmt
-                                         guards res_ty
-                                         (\res_ty' -> tcCmd env body (stk', res_ty'))
+       = do { (guards', rhs') <- tcStmts pg_ctxt tcGuardStmt guards res_ty $
+                                 tcGuardedCmd env body stk'
             ; return (GRHS guards' rhs') }
 
 -------------------------------------------
@@ -209,8 +217,8 @@ tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig g
 
 tc_cmd env cmd@(HsDo do_or_lc stmts body ty) (cmd_stk, res_ty)
   = do         { checkTc (null cmd_stk) (nonEmptyCmdStkErr cmd)
-       ; (stmts', body') <- tcStmts do_or_lc tc_stmt stmts res_ty $ \ res_ty' ->
-                            tcCmd env body ([], res_ty')
+       ; (stmts', body') <- tcStmts do_or_lc tc_stmt stmts (emptyRefinement, res_ty) $
+                            tcGuardedCmd env body []
        ; return (HsDo do_or_lc stmts' body' res_ty) }
   where
     tc_stmt = tcMDoStmt tc_rhs
@@ -256,7 +264,9 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
                -- the s1..sm and check each cmd
        ; cmds' <- mapM (tc_cmd w_tv) cmds_w_tys
 
-       ; returnM (HsArrForm (mkHsTyLam [w_tv] (mkHsDictLet inst_binds expr')) fixity cmds')
+       ; returnM (HsArrForm (noLoc $ HsCoerce (CoTyLams [w_tv]) 
+                                              (unLoc $ mkHsDictLet inst_binds expr')) 
+                            fixity cmds')
        }
   where
        -- Make the types       
@@ -264,7 +274,6 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
     new_cmd_ty :: LHsCmdTop Name -> Int
               -> TcM (LHsCmdTop Name, Int, TcType, TcType, TcType)
     new_cmd_ty cmd i
--- gaw 2004 FIX?
          = do  { b_ty   <- newFlexiTyVarTy arrowTyConKind
                ; tup_ty <- newFlexiTyVarTy liftedTypeKind
                        -- We actually make a type variable for the tuple
@@ -284,7 +293,7 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
                      not (w_tv `elemVarSet` tyVarsOfTypes arg_tys))
                     (badFormFun i tup_ty')
 
-          ; tcCmdTop (env { cmd_arr = b }) cmd (arg_tys, s) }
+          ; tcCmdTop (env { cmd_arr = b }) cmd arg_tys (emptyRefinement, s) }
 
     unscramble :: TcType -> (TcType, [TcType])
     -- unscramble ((w,s1) .. sn)       =  (w, [s1..sn])