Don't import FastString in HsVersions.h

[ghc-hetmet.git] / compiler / deSugar / MatchCon.lhs

diff --git a/compiler/deSugar/MatchCon.lhs b/compiler/deSugar/MatchCon.lhs
index 2612b50..4e9ee8e 100644 (file)
--- a/compiler/deSugar/MatchCon.lhs
+++ b/compiler/deSugar/MatchCon.lhs
@@ -1,28 +1,36 @@
-
+%
+% (c) The University of Glasgow 2006
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-\section[MatchCon]{Pattern-matching constructors}
+
+Pattern-matching constructors
 
 \begin{code}
+{-# OPTIONS -fno-warn-incomplete-patterns #-}
+-- 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 MatchCon ( matchConFamily ) where
 
 #include "HsVersions.h"
 
 import {-# SOURCE #-} Match    ( match )
 
-import HsSyn           ( Pat(..), LPat, HsConDetails(..) )
-import DsBinds         ( dsLHsBinds )
-import DataCon         ( DataCon, dataConInstOrigArgTys, 
-                         dataConFieldLabels, dataConSourceArity )
-import TcType          ( tcTyConAppArgs )
-import Type            ( mkTyVarTys )
+import HsSyn
+import DsBinds
+import DataCon
+import TcType
+import Type
 import CoreSyn
 import DsMonad
 import DsUtils
-
-import Id              ( Id, idName )
-import Type             ( Type )
-import SrcLoc          ( unLoc, Located(..) )
+import Util    ( takeList )
+import Id
+import Var      (TyVar)
+import SrcLoc
 import Outputable
 \end{code}
 
@@ -86,22 +94,29 @@ matchConFamily (var:vars) ty groups
   = do { alts <- mapM (matchOneCon vars ty) groups
        ; return (mkCoAlgCaseMatchResult var ty alts) }
 
+matchOneCon :: [Id]
+            -> Type
+            -> [EquationInfo]
+            -> DsM (DataCon, [TyVar], MatchResult)
 matchOneCon vars ty (eqn1 : eqns)      -- All eqns for a single constructor
   = do { (wraps, eqns') <- mapAndUnzipM shift (eqn1:eqns)
-       ; arg_vars <- selectMatchVars (take (dataConSourceArity con) 
+       ; arg_vars <- selectMatchVars (take (dataConSourceArity con1) 
                                            (eqn_pats (head eqns')))
                -- Use the new arugment patterns as a source of 
                -- suggestions for the new variables
        ; match_result <- match (arg_vars ++ vars) ty eqns'
-       ; return (con, tvs1 ++ dicts1 ++ arg_vars, 
+       ; return (con1, tvs1 ++ dicts1 ++ arg_vars, 
                  adjustMatchResult (foldr1 (.) wraps) match_result) }
   where
-    ConPatOut { pat_con = L _ con, pat_ty = pat_ty1,
+    ConPatOut { pat_con = L _ con1, pat_ty = pat_ty1,
                pat_tvs = tvs1, pat_dicts = dicts1 } = firstPat eqn1
        
-    arg_tys  = dataConInstOrigArgTys con inst_tys
-    inst_tys = tcTyConAppArgs pat_ty1 ++ mkTyVarTys tvs1
+    arg_tys  = dataConInstOrigArgTys con1 inst_tys
+    inst_tys = tcTyConAppArgs pat_ty1 ++ 
+              mkTyVarTys (takeList (dataConExTyVars con1) tvs1)
        -- Newtypes opaque, hence tcTyConAppArgs
+       -- dataConInstOrigArgTys takes the univ and existential tyvars
+       -- and returns the types of the *value* args, which is what we want
 
     shift eqn@(EqnInfo { eqn_pats = ConPatOut{ pat_tvs = tvs, pat_dicts = ds, 
                                               pat_binds = bind, pat_args = args
@@ -110,15 +125,17 @@ matchOneCon vars ty (eqn1 : eqns) -- All eqns for a single constructor
             ; return (wrapBinds (tvs `zip` tvs1) 
                       . wrapBinds (ds  `zip` dicts1)
                       . mkDsLet (Rec prs),
-                      eqn { eqn_pats = conArgPats con arg_tys args ++ pats }) }
+                      eqn { eqn_pats = conArgPats con1 arg_tys args ++ pats }) }
 
 conArgPats :: DataCon 
           -> [Type]    -- Instantiated argument types 
-          -> HsConDetails Id (LPat Id)
+                       -- Used only to fill in the types of WildPats, which
+                       -- are probably never looked at anyway
+          -> HsConDetails (LPat Id) (HsRecFields Id (LPat Id))
           -> [Pat Id]
-conArgPats data_con arg_tys (PrefixCon ps)   = map unLoc ps
-conArgPats data_con arg_tys (InfixCon p1 p2) = [unLoc p1, unLoc p2]
-conArgPats data_con arg_tys (RecCon rpats)
+conArgPats _data_con _arg_tys (PrefixCon ps)   = map unLoc ps
+conArgPats _data_con _arg_tys (InfixCon p1 p2) = [unLoc p1, unLoc p2]
+conArgPats  data_con  arg_tys (RecCon (HsRecFields rpats _))
   | null rpats
   =    -- Special case for C {}, which can be used for 
        -- a constructor that isn't declared to have
@@ -131,7 +148,7 @@ conArgPats data_con arg_tys (RecCon rpats)
        -- mk_pat picks a WildPat of the appropriate type for absent fields,
        -- and the specified pattern for present fields
     mk_pat lbl arg_ty
-       = case [ pat | (sel_id,pat) <- rpats, idName (unLoc sel_id) == lbl] of
+       = case [ pat | HsRecField sel_id pat _ <- rpats, idName (unLoc sel_id) == lbl ] of
            (pat:pats) -> ASSERT( null pats ) unLoc pat
            []         -> WildPat arg_ty
 \end{code}