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

diff --git a/compiler/typecheck/TcArrows.lhs b/compiler/typecheck/TcArrows.lhs
index 3bfa9b4..0055d64 100644 (file)
--- a/compiler/typecheck/TcArrows.lhs
+++ b/compiler/typecheck/TcArrows.lhs
@@ -1,9 +1,17 @@
 %
 %

+% (c) The University of Glasgow 2006

 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %

-\section{Typecheck arrow notation}
+Typecheck arrow notation

 
 \begin{code}
 
 \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/Commentary/CodingStyle#Warnings
+-- for details
+

 module TcArrows ( tcProc ) where
 
 #include "HsVersions.h"
 module TcArrows ( tcProc ) where
 
 #include "HsVersions.h"

@@ -11,31 +19,29 @@ module TcArrows ( tcProc ) where
 import {-# SOURCE #-}  TcExpr( tcMonoExpr, tcInferRho )
 
 import HsSyn
 import {-# SOURCE #-}  TcExpr( tcMonoExpr, tcInferRho )
 
 import HsSyn

-import TcHsSyn (  mkHsDictLet )
-
-import TcMatches ( matchCtxt, tcStmts, tcMDoStmt, tcGuardStmt,
-                  TcMatchCtxt(..), tcMatchesCase )
-
-import TcType  ( TcType, TcTauType, BoxyRhoType, mkFunTys, mkTyConApp,
-                 mkTyVarTy, mkAppTys, tcSplitTyConApp_maybe, tcEqType, 
-                 SkolemInfo(..) )
-import TcMType ( newFlexiTyVarTy, tcInstSkolTyVars, zonkTcType )
-import TcBinds ( tcLocalBinds )
-import TcSimplify ( tcSimplifyCheck )
-import TcPat   ( tcPat, tcPats, PatCtxt(..) )
-import TcUnify ( checkSigTyVarsWrt, boxySplitAppTy )
+import TcHsSyn
+
+import TcMatches
+
+import TcType
+import TcMType
+import TcBinds
+import TcSimplify
+import TcGadt
+import TcPat
+import TcUnify

 import TcRnMonad
 import TcRnMonad

-import Inst    ( tcSyntaxName )
-import Name    ( Name )
-import TysWiredIn ( boolTy, pairTyCon )
+import Coercion
+import Inst
+import Name
+import TysWiredIn

 import VarSet 
 import VarSet 

-import TysPrim ( alphaTyVar )
-import Type    ( Kind, mkArrowKinds, liftedTypeKind, openTypeKind, tyVarsOfTypes )
+import TysPrim
+import Type

 
 

-import SrcLoc  ( Located(..) )
+import SrcLoc

 import Outputable
 import Outputable

-import Util    ( lengthAtLeast )
-
+import Util

 \end{code}
 
 %************************************************************************
 \end{code}
 
 %************************************************************************

@@ -47,16 +53,18 @@ import Util ( lengthAtLeast )
 \begin{code}
 tcProc :: InPat Name -> LHsCmdTop Name         -- proc pat -> expr
        -> BoxyRhoType                          -- Expected type of whole proc expression
 \begin{code}
 tcProc :: InPat Name -> LHsCmdTop Name         -- proc pat -> expr
        -> BoxyRhoType                          -- Expected type of whole proc expression

-       -> TcM (OutPat TcId, LHsCmdTop TcId)
+       -> TcM (OutPat TcId, LHsCmdTop TcId, CoercionI)

 
 tcProc pat cmd exp_ty
   = newArrowScope $
 
 tcProc pat cmd exp_ty
   = newArrowScope $

-    do { (exp_ty1, res_ty) <- boxySplitAppTy exp_ty 
-       ; (arr_ty, arg_ty)  <- boxySplitAppTy exp_ty1
+    do { ((exp_ty1, res_ty), coi) <- boxySplitAppTy exp_ty 
+       ; ((arr_ty, arg_ty), coi1) <- boxySplitAppTy exp_ty1

        ; let cmd_env = CmdEnv { cmd_arr = arr_ty }
        ; 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')
-       ; return (pat', cmd') }
+       ; (pat', cmd') <- tcLamPat pat arg_ty (emptyRefinement, res_ty) $
+                         tcCmdTop cmd_env cmd []
+        ; let res_coi = mkTransCoI coi (mkAppTyCoI exp_ty1 coi1 res_ty IdCo)
+       ; return (pat', cmd', res_coi) 
+        }

 \end{code}
 
 
 \end{code}
 
 

@@ -79,20 +87,29 @@ mkCmdArrTy env t1 t2 = mkAppTys (cmd_arr env) [t1, t2]
 ---------------------------------------
 tcCmdTop :: CmdEnv 
          -> LHsCmdTop Name
 ---------------------------------------
 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)
 
                                        -- 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 $
   = 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') }
 
 
 ----------------------------------------
        ; 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 (mkLHsWrap co body) }
+

 tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
        -- The main recursive function
 tcCmd env (L loc expr) res_ty
 tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
        -- The main recursive function
 tcCmd env (L loc expr) res_ty

@@ -120,7 +137,7 @@ tc_cmd env in_cmd@(HsCase scrut matches) (stk, res_ty)
   where
     match_ctxt = MC { mc_what = CaseAlt,
                       mc_body = mc_body }
   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
 
 tc_cmd env (HsIf pred b1 b2) res_ty
   = do         { pred' <- tcMonoExpr pred boolTy

@@ -169,7 +186,6 @@ tc_cmd env cmd@(HsApp fun arg) (cmd_stk, res_ty)
 -------------------------------------------
 --             Lambda
 
 -------------------------------------------
 --             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)    $
 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 +196,7 @@ 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                $
 
                -- 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')
                             tc_grhss grhss
 
        ; let match' = L mtch_loc (Match pats' Nothing grhss')

@@ -190,7 +206,7 @@ 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
   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
     pg_ctxt    = PatGuard match_ctxt
 
     tc_grhss (GRHSs grhss binds) res_ty

@@ -199,9 +215,8 @@ 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)
             ; 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') }
 
 -------------------------------------------
             ; return (GRHS guards' rhs') }
 
 -------------------------------------------

@@ -209,8 +224,8 @@ 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)
 
 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
        ; return (HsDo do_or_lc stmts' body' res_ty) }
   where
     tc_stmt = tcMDoStmt tc_rhs

@@ -233,7 +248,7 @@ 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
   = addErrCtxt (cmdCtxt cmd)   $
     do { cmds_w_tys <- zipWithM new_cmd_ty cmd_args [1..]
        ; span       <- getSrcSpanM

-       ; [w_tv]     <- tcInstSkolTyVars (ArrowSkol span) [alphaTyVar]
+       ; [w_tv]     <- tcInstSkolTyVars ArrowSkol [alphaTyVar]

        ; let w_ty = mkTyVarTy w_tv     -- Just a convenient starting point
 
                --  a ((w,t1) .. tn) t
        ; let w_ty = mkTyVarTy w_tv     -- Just a convenient starting point
 
                --  a ((w,t1) .. tn) t

@@ -246,7 +261,8 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
 
                -- Check expr
        ; (expr', lie) <- escapeArrowScope (getLIE (tcMonoExpr expr e_ty))
 
                -- Check expr
        ; (expr', lie) <- escapeArrowScope (getLIE (tcMonoExpr expr e_ty))

-       ; inst_binds <- tcSimplifyCheck sig_msg [w_tv] [] lie
+       ; 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)
 
                -- 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)

@@ -256,7 +272,9 @@ 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
 
                -- 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 $ HsWrap (WpTyLam w_tv) 
+                                              (unLoc $ mkHsDictLet inst_binds expr')) 
+                            fixity cmds')

        }
   where
        -- Make the types       
        }
   where
        -- Make the types       

@@ -264,7 +282,6 @@ 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
     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
          = do  { b_ty   <- newFlexiTyVarTy arrowTyConKind
                ; tup_ty <- newFlexiTyVarTy liftedTypeKind
                        -- We actually make a type variable for the tuple

@@ -284,7 +301,7 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
                      not (w_tv `elemVarSet` tyVarsOfTypes arg_tys))
                     (badFormFun i tup_ty')
 
                      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])
 
     unscramble :: TcType -> (TcType, [TcType])
     -- unscramble ((w,s1) .. sn)       =  (w, [s1..sn])

@@ -297,8 +314,6 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
                                    
            other -> (ty, [])
 
                                    
            other -> (ty, [])
 

-    sig_msg  = ptext SLIT("expected type of a command form")
-

 -----------------------------------------------------------------
 --             Base case for illegal commands
 -- This is where expressions that aren't commands get rejected
 -----------------------------------------------------------------
 --             Base case for illegal commands
 -- This is where expressions that aren't commands get rejected