Tidy-up sweep, following the Great Skolemisation Simplification

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

diff --git a/compiler/typecheck/TcArrows.lhs b/compiler/typecheck/TcArrows.lhs
index 9fede38..227c6ce 100644 (file)
--- a/compiler/typecheck/TcArrows.lhs
+++ b/compiler/typecheck/TcArrows.lhs
@@ -10,14 +10,10 @@ module TcArrows ( tcProc ) where
 import {-# SOURCE #-}  TcExpr( tcMonoExpr, tcInferRho )
 
 import HsSyn
-import TcHsSyn
-
 import TcMatches
-
 import TcType
 import TcMType
 import TcBinds
-import TcSimplify
 import TcPat
 import TcUnify
 import TcRnMonad
@@ -44,19 +40,18 @@ import Control.Monad
 
 \begin{code}
 tcProc :: InPat Name -> LHsCmdTop Name         -- proc pat -> expr
-       -> BoxyRhoType                          -- Expected type of whole proc expression
+       -> TcRhoType                            -- Expected type of whole proc expression
        -> TcM (OutPat TcId, LHsCmdTop TcId, CoercionI)
 
 tcProc pat cmd exp_ty
   = newArrowScope $
-    do { ((exp_ty1, res_ty), coi) <- boxySplitAppTy exp_ty 
-       ; ((arr_ty, arg_ty), coi1) <- 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') <- tcPat ProcExpr pat arg_ty res_ty $
-                         tcCmdTop cmd_env cmd []
-        ; let res_coi = mkTransCoI coi (mkAppTyCoI exp_ty1 coi1 res_ty IdCo)
-       ; return (pat', cmd', res_coi) 
-        }
+       ; (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}
 
 
@@ -185,9 +180,9 @@ tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats _maybe_rhs_sig
                  (kappaUnderflow cmd)
 
                -- Check the patterns, and the GRHSs inside
-       ; (pats', grhss') <- setSrcSpan mtch_loc                        $
-                            tcPats LambdaExpr pats cmd_stk res_ty      $
-                            tc_grhss grhss
+       ; (pats', grhss') <- setSrcSpan mtch_loc                $
+                            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))
@@ -214,11 +209,10 @@ tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats _maybe_rhs_sig
 
 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 $
+       ; (stmts', body') <- tcStmts do_or_lc (tcMDoStmt tc_rhs) stmts res_ty $
                             tcGuardedCmd env body []
        ; return (HsDo do_or_lc stmts' body' res_ty) }
   where
-    tc_stmt = tcMDoStmt tc_rhs
     tc_rhs rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
                    ; rhs' <- tcCmd env rhs ([], ty)
                    ; return (rhs', ty) }
@@ -249,22 +243,15 @@ 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
 
-       ; return (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
@@ -294,14 +281,13 @@ tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
 
     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)
-                                   
-           _ -> (ty, [])
+              ->  unscramble' t (s:ss)
+           _ -> (ty, ss)
 
 -----------------------------------------------------------------
 --             Base case for illegal commands
@@ -342,15 +328,15 @@ 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)
+       2 (ppr cmd)
 
 kappaUnderflow :: HsExpr Name -> SDoc
 kappaUnderflow cmd
   = hang (ptext (sLit "Command stack underflow at command:"))
-        4 (ppr cmd)
+       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')
+      2 (ptext (sLit "Argument type:") <+> ppr tup_ty')
 \end{code}