[project @ 2004-11-18 00:56:18 by igloo]

[ghc-hetmet.git] / ghc / compiler / hsSyn / HsTypes.lhs

diff --git a/ghc/compiler/hsSyn/HsTypes.lhs b/ghc/compiler/hsSyn/HsTypes.lhs
index fdcc3e2..03d414a 100644 (file)
--- a/ghc/compiler/hsSyn/HsTypes.lhs
+++ b/ghc/compiler/hsSyn/HsTypes.lhs
@@ -10,6 +10,9 @@ module HsTypes (
        HsExplicitForAll(..),
        HsContext, LHsContext,
        HsPred(..), LHsPred,
+
+       LBangType, BangType, HsBang(..), 
+        getBangType, getBangStrictness, 
        
        mkExplicitHsForAllTy, mkImplicitHsForAllTy, 
        hsTyVarName, hsTyVarNames, replaceTyVarName,
@@ -71,6 +74,35 @@ placeHolderName = mkInternalName unboundKey
                        noSrcLoc
 \end{code}
 
+%************************************************************************
+%*                                                                     *
+\subsection{Bang annotations}
+%*                                                                     *
+%************************************************************************
+
+\begin{code}
+type LBangType name = Located (BangType name)
+type BangType name  = HsType name      -- Bangs are in the HsType data type
+
+data HsBang = HsNoBang -- Only used as a return value for getBangStrictness,
+                       -- never appears on a HsBangTy
+           | HsStrict  -- ! 
+           | HsUnbox   -- {-# UNPACK #-} ! (GHC extension, meaning "unbox")
+
+instance Outputable HsBang where
+    ppr (HsNoBang) = empty
+    ppr (HsStrict) = char '!'
+    ppr (HsUnbox)  = ptext SLIT("!!")
+
+getBangType :: LHsType a -> LHsType a
+getBangType (L _ (HsBangTy _ ty)) = ty
+getBangType ty                    = ty
+
+getBangStrictness :: LHsType a -> HsBang
+getBangStrictness (L _ (HsBangTy s _)) = s
+getBangStrictness _                    = HsNoBang
+\end{code}
+
 
 %************************************************************************
 %*                                                                     *
@@ -103,6 +135,8 @@ data HsType name
 
   | HsTyVar            name            -- Type variable or type constructor
 
+  | HsBangTy   HsBang (LHsType name)   -- Bang-style type annotations 
+
   | HsAppTy            (LHsType name)
                        (LHsType name)
 
@@ -210,36 +244,15 @@ splitHsInstDeclTy
     -> ([LHsTyVarBndr name], HsContext name, name, [LHsType name])
        -- Split up an instance decl type, returning the pieces
 
--- In interface files, the instance declaration head is created
--- by HsTypes.toHsType, which does not guarantee to produce a
--- HsForAllTy.  For example, if we had the weird decl
---     instance Foo T => Foo [T]
--- then we'd get the instance type
---     Foo T -> Foo [T]
--- So when colleting the instance context, to be on the safe side
--- we gather predicate arguments
--- 
--- For source code, the parser ensures the type will have the right shape.
--- (e.g. see ParseUtil.checkInstType)
-
 splitHsInstDeclTy inst_ty
   = case inst_ty of
-       HsForAllTy _ tvs cxt1 tau       -- The type vars should have been
-                                       -- computed by now, even if they were implicit
-             -> (tvs, unLoc cxt1 ++ cxt2, cls, tys)
-             where
-                (cxt2, cls, tys) = split_tau (unLoc tau)
-
-       other -> ([],  cxt2,  cls, tys)
-             where
-                (cxt2, cls, tys) = split_tau inst_ty
-
+       HsParTy (L _ ty)              -> splitHsInstDeclTy ty
+       HsForAllTy _ tvs cxt (L _ ty) -> split_tau tvs (unLoc cxt) ty
+       other                         -> split_tau []  []          other
+    -- The type vars should have been computed by now, even if they were implicit
   where
-    split_tau (HsFunTy (L loc (HsPredTy p)) ty) = (L loc p : ps, cls, tys)
-                                       where
-                                         (ps, cls, tys) = split_tau (unLoc ty)
-    split_tau (HsPredTy (HsClassP cls tys)) = ([], cls, tys)
-    split_tau other = pprPanic "splitHsInstDeclTy" (ppr inst_ty)
+    split_tau tvs cxt (HsPredTy (HsClassP cls tys)) = (tvs, cxt, cls, tys)
+    split_tau tvs cxt (HsParTy (L _ ty))           = split_tau tvs cxt ty
 \end{code}
 
 
@@ -320,6 +333,8 @@ ppr_mono_ty ctxt_prec (HsForAllTy exp tvs ctxt ty)
   = maybeParen ctxt_prec pREC_FUN $
     sep [pprHsForAll exp tvs ctxt, ppr_mono_lty pREC_TOP ty]
 
+-- gaw 2004
+ppr_mono_ty ctxt_prec (HsBangTy b ty)     = ppr b <> ppr ty
 ppr_mono_ty ctxt_prec (HsTyVar name)      = ppr name
 ppr_mono_ty ctxt_prec (HsFunTy ty1 ty2)   = ppr_fun_ty ctxt_prec ty1 ty2
 ppr_mono_ty ctxt_prec (HsTupleTy con tys) = tupleParens con (interpp'SP tys)