X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcArrows.lhs;h=5d9273880ff07f125851f70472aad17564190c11;hp=efd01c904fd99071a2728e4e7b895f76f965b35a;hb=d76d9636aeebe933d160157331b8c8c0087e73ac;hpb=ad94d40948668032189ad22a0ad741ac1f645f50

diff --git a/compiler/typecheck/TcArrows.lhs b/compiler/typecheck/TcArrows.lhs
index efd01c9..5d92738 100644
--- a/compiler/typecheck/TcArrows.lhs
+++ b/compiler/typecheck/TcArrows.lhs
@@ -5,42 +5,31 @@
 Typecheck arrow notation
 
 \begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
---     http://hackage.haskell.org/trac/ghc/wiki/CodingStyle#Warnings
--- for details
-
 module TcArrows ( tcProc ) where
 
-#include "HsVersions.h"
-
-import {-# SOURCE #-}	TcExpr( tcMonoExpr, tcInferRho )
+import {-# SOURCE #-}	TcExpr( tcMonoExpr, tcInferRho, tcSyntaxOp )
 
 import HsSyn
-import TcHsSyn
-
 import TcMatches
-
 import TcType
 import TcMType
 import TcBinds
-import TcSimplify
-import TcGadt
 import TcPat
 import TcUnify
 import TcRnMonad
+import Coercion
 import Inst
 import Name
 import TysWiredIn
 import VarSet 
 import TysPrim
-import Type
 
 import SrcLoc
 import Outputable
+import FastString
 import Util
+
+import Control.Monad
 \end{code}
 
 %************************************************************************
@@ -51,17 +40,18 @@ import Util
 
 \begin{code}
 tcProc :: InPat Name -> LHsCmdTop Name		-- proc pat -> expr
-       -> BoxyRhoType				-- Expected type of whole proc expression
-       -> TcM (OutPat TcId, LHsCmdTop TcId)
+       -> TcRhoType				-- Expected type of whole proc expression
+       -> TcM (OutPat TcId, LHsCmdTop TcId, CoercionI)
 
 tcProc pat cmd exp_ty
   = newArrowScope $
-    do	{ (exp_ty1, res_ty) <- boxySplitAppTy exp_ty 
-	; (arr_ty, arg_ty)  <- boxySplitAppTy exp_ty1
+    do	{ (coi, (exp_ty1, res_ty)) <- matchExpectedAppTy exp_ty 
+	; (coi1, (arr_ty, arg_ty)) <- matchExpectedAppTy exp_ty1
 	; let cmd_env = CmdEnv { cmd_arr = arr_ty }
-	; (pat', cmd') <- tcLamPat pat arg_ty (emptyRefinement, res_ty) $
-			  tcCmdTop cmd_env cmd []
-	; return (pat', cmd') }
+	; (pat', cmd') <- tcPat ProcExpr pat arg_ty $
+			  tcCmdTop cmd_env cmd [] res_ty
+        ; let res_coi = mkTransCoI coi (mkAppTyCoI coi1 (IdCo res_ty))
+	; return (pat', cmd', res_coi) }
 \end{code}
 
 
@@ -85,27 +75,27 @@ mkCmdArrTy env t1 t2 = mkAppTys (cmd_arr env) [t1, t2]
 tcCmdTop :: CmdEnv 
          -> LHsCmdTop Name
          -> 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
+	 -> 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 reft_res_ty@(_,res_ty)
+tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) cmd_stk res_ty
   = setSrcSpan loc $
-    do	{ cmd'   <- tcGuardedCmd env cmd cmd_stk reft_res_ty
+    do	{ cmd'   <- tcGuardedCmd env cmd cmd_stk 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)
+	     -> 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 (mkLHsWrap co body) }
+tcGuardedCmd env expr stk res_ty
+  = do	{ body <- tcCmd env expr (stk, res_ty)
+	; return body 
+        }
 
 tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
 	-- The main recursive function
@@ -114,6 +104,7 @@ tcCmd env (L loc expr) res_ty
 	{ expr' <- tc_cmd env expr res_ty
 	; return (L loc expr') }
 
+tc_cmd :: CmdEnv -> HsExpr Name -> (CmdStack, TcTauType) -> TcM (HsExpr TcId)
 tc_cmd env (HsPar cmd) res_ty
   = do	{ cmd' <- tcCmd env cmd res_ty
 	; return (HsPar cmd') }
@@ -125,22 +116,26 @@ tc_cmd env (HsLet binds (L body_loc body)) res_ty
 	; return (HsLet binds' (L body_loc body')) }
 
 tc_cmd env in_cmd@(HsCase scrut matches) (stk, res_ty)
-  = addErrCtxt (cmdCtxt in_cmd)		$
-    addErrCtxt (caseScrutCtxt scrut)	(
-      tcInferRho scrut 
-    )							`thenM`	\ (scrut', scrut_ty) ->
-    tcMatchesCase match_ctxt scrut_ty matches res_ty	`thenM`	\ matches' ->
-    returnM (HsCase scrut' matches')
+  = addErrCtxt (cmdCtxt in_cmd) $ do
+      (scrut', scrut_ty) <- tcInferRho scrut 
+      matches' <- tcMatchesCase match_ctxt scrut_ty matches res_ty
+      return (HsCase scrut' matches')
   where
     match_ctxt = MC { mc_what = CaseAlt,
                       mc_body = mc_body }
     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
-	; b1'   <- tcCmd env b1 res_ty
-	; b2'   <- tcCmd env b2 res_ty
-	; return (HsIf pred' b1' b2')
+tc_cmd env (HsIf mb_fun pred b1 b2) (stack_ty,res_ty)
+  = do 	{ pred_ty <- newFlexiTyVarTy openTypeKind
+	; b_ty <- newFlexiTyVarTy openTypeKind
+        ; let if_ty = mkFunTys [pred_ty, b_ty, b_ty] res_ty
+	; mb_fun' <- case mb_fun of 
+              Nothing  -> return Nothing
+              Just fun -> liftM Just (tcSyntaxOp IfOrigin fun if_ty)
+  	; pred' <- tcMonoExpr pred pred_ty
+	; b1'   <- tcCmd env b1 (stack_ty,b_ty)
+	; b2'   <- tcCmd env b2 (stack_ty,b_ty)
+	; return (HsIf mb_fun' pred' b1' b2')
     }
 
 -------------------------------------------
@@ -171,7 +166,6 @@ tc_cmd env cmd@(HsArrApp fun arg _ ho_app lr) (cmd_stk, res_ty)
 
 tc_cmd env cmd@(HsApp fun arg) (cmd_stk, res_ty)
   = addErrCtxt (cmdCtxt cmd)	$
--- gaw 2004 FIX?
     do  { arg_ty <- newFlexiTyVarTy openTypeKind
 
 	; fun' <- tcCmd env fun (arg_ty:cmd_stk, res_ty)
@@ -183,9 +177,9 @@ tc_cmd env cmd@(HsApp fun arg) (cmd_stk, res_ty)
 -------------------------------------------
 -- 		Lambda
 
-tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig grhss))] _))
+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)	$
+  = addErrCtxt (pprMatchInCtxt match_ctxt match)	$
 
     do	{ 	-- Check the cmd stack is big enough
 	; checkTc (lengthAtLeast cmd_stk n_pats)
@@ -193,8 +187,8 @@ 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		$
-			     tcLamPats pats cmd_stk res_ty	$
-			     tc_grhss grhss
+			     tcPats LambdaExpr pats cmd_stk	$
+			     tc_grhss grhss res_ty
 
 	; let match' = L mtch_loc (Match pats' Nothing grhss')
 	; return (HsLam (MatchGroup [match'] res_ty))
@@ -203,7 +197,7 @@ tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig g
   where
     n_pats     = length pats
     stk'       = drop n_pats cmd_stk
-    match_ctxt = LambdaExpr 	-- Maybe KappaExpr?
+    match_ctxt = (LambdaExpr :: HsMatchContext Name)	-- Maybe KappaExpr?
     pg_ctxt    = PatGuard match_ctxt
 
     tc_grhss (GRHSs grhss binds) res_ty
@@ -212,20 +206,18 @@ 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 $
+	= do { (guards', rhs') <- tcStmtsAndThen pg_ctxt tcGuardStmt guards res_ty $
 				  tcGuardedCmd env body stk'
 	     ; return (GRHS guards' rhs') }
 
 -------------------------------------------
 -- 		Do notation
 
-tc_cmd env cmd@(HsDo do_or_lc stmts body ty) (cmd_stk, res_ty)
+tc_cmd env cmd@(HsDo do_or_lc stmts _) (cmd_stk, res_ty)
   = do 	{ checkTc (null cmd_stk) (nonEmptyCmdStkErr cmd)
-	; (stmts', body') <- tcStmts do_or_lc tc_stmt stmts (emptyRefinement, res_ty) $
-			     tcGuardedCmd env body []
-	; return (HsDo do_or_lc stmts' body' res_ty) }
+	; stmts' <- tcStmts do_or_lc (tcMDoStmt tc_rhs) stmts res_ty 
+	; return (HsDo do_or_lc stmts' res_ty) }
   where
-    tc_stmt = tcMDoStmt tc_rhs
     tc_rhs rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
 		    ; rhs' <- tcCmd env rhs ([], ty)
 		    ; return (rhs', ty) }
@@ -244,8 +236,7 @@ tc_cmd env cmd@(HsDo do_or_lc stmts body ty) (cmd_stk, res_ty)
 tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)	
   = addErrCtxt (cmdCtxt cmd)	$
     do	{ cmds_w_tys <- zipWithM new_cmd_ty cmd_args [1..]
-	; span       <- getSrcSpanM
-	; [w_tv]     <- tcInstSkolTyVars ArrowSkol [alphaTyVar]
+        ; [w_tv]     <- tcInstSkolTyVars [alphaTyVar]
 	; let w_ty = mkTyVarTy w_tv 	-- Just a convenient starting point
 
 		--  a ((w,t1) .. tn) t
@@ -257,22 +248,15 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
 			      e_res_ty
 
 		-- Check expr
-	; (expr', lie) <- escapeArrowScope (getLIE (tcMonoExpr expr e_ty))
-	; loc <- getInstLoc (SigOrigin ArrowSkol)
-	; inst_binds <- tcSimplifyCheck loc [w_tv] [] lie
-
-		-- Check that the polymorphic variable hasn't been unified with anything
-		-- and is not free in res_ty or the cmd_stk  (i.e.  t, t1..tn)
-	; checkSigTyVarsWrt (tyVarsOfTypes (res_ty:cmd_stk)) [w_tv] 
+	; (inst_binds, expr') <- checkConstraints ArrowSkol [w_tv] [] $
+                                 escapeArrowScope (tcMonoExpr expr e_ty)
 
 		-- OK, now we are in a position to unscramble 
 		-- the s1..sm and check each cmd
 	; cmds' <- mapM (tc_cmd w_tv) cmds_w_tys
 
-	; returnM (HsArrForm (noLoc $ HsWrap (WpTyLam w_tv) 
-					       (unLoc $ mkHsDictLet inst_binds expr')) 
-			     fixity cmds')
-	}
+        ; let wrap = WpTyLam w_tv <.> mkWpLet inst_binds
+	; return (HsArrForm (mkLHsWrap wrap expr') fixity cmds') }
   where
  	-- Make the types	
 	--	b, ((e,s1) .. sm), s
@@ -298,26 +282,25 @@ 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 (emptyRefinement, s) }
+	   ; tcCmdTop (env { cmd_arr = b }) cmd arg_tys s }
 
     unscramble :: TcType -> (TcType, [TcType])
     -- unscramble ((w,s1) .. sn)	=  (w, [s1..sn])
-    unscramble ty
+    unscramble ty = unscramble' ty []
+
+    unscramble' ty ss
        = case tcSplitTyConApp_maybe ty of
 	    Just (tc, [t,s]) | tc == pairTyCon 
-	       ->  let 
-		      (w,ss) = unscramble t  
-		   in (w, s:ss)
-				    
-	    other -> (ty, [])
+	       ->  unscramble' t (s:ss)
+	    _ -> (ty, ss)
 
 -----------------------------------------------------------------
 --		Base case for illegal commands
 -- This is where expressions that aren't commands get rejected
 
-tc_cmd env cmd _
-  = failWithTc (vcat [ptext SLIT("The expression"), nest 2 (ppr cmd), 
-		      ptext SLIT("was found where an arrow command was expected")])
+tc_cmd _ cmd _
+  = failWithTc (vcat [ptext (sLit "The expression"), nest 2 (ppr cmd), 
+		      ptext (sLit "was found where an arrow command was expected")])
 \end{code}
 
 
@@ -329,6 +312,7 @@ tc_cmd env cmd _
 
 
 \begin{code}
+mkPairTy :: Type -> Type -> Type
 mkPairTy t1 t2 = mkTyConApp pairTyCon [t1,t2]
 
 arrowTyConKind :: Kind		--  *->*->*
@@ -343,20 +327,21 @@ arrowTyConKind = mkArrowKinds [liftedTypeKind, liftedTypeKind] liftedTypeKind
 %************************************************************************
 
 \begin{code}
-cmdCtxt cmd = ptext SLIT("In the command:") <+> ppr cmd
-
-caseScrutCtxt cmd
-  = hang (ptext SLIT("In the scrutinee of a case command:")) 4 (ppr cmd)
+cmdCtxt :: HsExpr Name -> SDoc
+cmdCtxt cmd = ptext (sLit "In the command:") <+> ppr cmd
 
+nonEmptyCmdStkErr :: HsExpr Name -> SDoc
 nonEmptyCmdStkErr cmd
-  = hang (ptext SLIT("Non-empty command stack at command:"))
-	 4 (ppr cmd)
+  = hang (ptext (sLit "Non-empty command stack at command:"))
+       2 (ppr cmd)
 
+kappaUnderflow :: HsExpr Name -> SDoc
 kappaUnderflow cmd
-  = hang (ptext SLIT("Command stack underflow at command:"))
-	 4 (ppr cmd)
+  = hang (ptext (sLit "Command stack underflow at command:"))
+       2 (ppr cmd)
 
+badFormFun :: Int -> TcType -> SDoc
 badFormFun i tup_ty'
- = hang (ptext SLIT("The type of the") <+> speakNth i <+> ptext SLIT("argument of a command form has the wrong shape"))
-	4 (ptext SLIT("Argument type:") <+> ppr tup_ty')
+ = hang (ptext (sLit "The type of the") <+> speakNth i <+> ptext (sLit "argument of a command form has the wrong shape"))
+      2 (ptext (sLit "Argument type:") <+> ppr tup_ty')
 \end{code}