[project @ 2004-02-24 16:44:26 by simonpj]

---------------------------------------
      Allow constructors to be specified in hi-boot files
	  ---------------------------------------

ghc/compiler/parser/Parser.y.pp

@@ -327,10 +327,12 @@ ifacedecl :: { HsDecl RdrName }
                 { SigD (Sig $1 $3) }
  	| 'type' syn_hdr '=' ctype	
  		{ let (tc,tvs) = $2 in TyClD (TySynonym tc tvs $4) }
-	| 'data' tycl_hdr
-		{ TyClD (mkTyData DataType (unLoc $2) [] Nothing) }
-	| 'newtype' tycl_hdr
+	| 'data' tycl_hdr constrs	-- No deriving in hi-boot
+		{ TyClD (mkTyData DataType (unLoc $2) (reverse (unLoc $3)) Nothing) }
+	| 'newtype' tycl_hdr 		-- Constructor is optional
 		{ TyClD (mkTyData NewType (unLoc $2) [] Nothing) }
+	| 'newtype' tycl_hdr '=' newconstr
+		{ TyClD (mkTyData NewType (unLoc $2) [$4] Nothing) }
 	| 'class' tycl_hdr fds
 		{ TyClD (mkClassDecl (unLoc $2) (unLoc $3) [] emptyBag) }
 

ghc/compiler/parser/RdrHsSyn.lhs

@@ -51,7 +51,7 @@ module RdrHsSyn (
 import HsSyn		-- Lots of it
 import IfaceType
 import HscTypes		( ModIface(..), emptyModIface, mkIfaceVerCache )
-import IfaceSyn		( IfaceDecl(..), IfaceIdInfo(..) )
+import IfaceSyn		( IfaceDecl(..), IfaceIdInfo(..), IfaceConDecl(..) )
 import RdrName		( RdrName, isRdrTyVar, mkUnqual, rdrNameOcc, 
 			  isRdrTyVar, isRdrDataCon, isUnqual, getRdrName, isQual,
 			  setRdrNameSpace, rdrNameModule )
@@ -64,7 +64,7 @@ import ForeignCall	( CCallConv, Safety, CCallTarget(..), CExportSpec(..),
 			  DNCallSpec(..), DNKind(..))
 import OccName  	( OccName, srcDataName, varName, isDataOcc, isTcOcc, 
 			  occNameUserString, isValOcc )
-import BasicTypes	( initialVersion )
+import BasicTypes	( initialVersion, StrictnessMark(..) )
 import TyCon		( DataConDetails(..) )
 import Module		( ModuleName )
 import SrcLoc
@@ -246,7 +246,8 @@ hsIfaceDecl (TyClD decl@(TyData {}))
 	        ifName = rdrNameOcc (tcdName decl), 
 	        ifTyVars = hsIfaceTvs (tcdTyVars decl), 
 		ifCtxt = hsIfaceCtxt (unLoc (tcdCtxt decl)),
-		ifCons = Unknown, ifRec = NonRecursive,
+		ifCons = hsIfaceCons (tcdCons decl), 
+		ifRec = NonRecursive,
 		ifVrcs = [], ifGeneric = False }
 	-- I'm not sure that [] is right for ifVrcs, but
 	-- since we don't use them I'm not going to fiddle
@@ -261,6 +262,35 @@ hsIfaceDecl (TyClD decl@(ClassDecl {}))
 
 hsIfaceDecl decl = pprPanic "hsIfaceDecl" (ppr decl)
 
+hsIfaceCons :: [LConDecl RdrName] -> DataConDetails IfaceConDecl
+hsIfaceCons cons
+  | null cons 	-- data T a, meaning "constructors unspecified", not "no constructors"
+  = Unknown	
+  | otherwise	-- data T a = C1 | C2 
+  = DataCons (map (hsIfaceCon . unLoc) cons)
+
+hsIfaceCon :: ConDecl RdrName -> IfaceConDecl
+hsIfaceCon (ConDecl lname ex_tvs ex_ctxt details)
+  = IfaceConDecl (get_occ lname)
+		 (hsIfaceTvs ex_tvs)
+		 (hsIfaceCtxt (unLoc ex_ctxt))
+		 (map (hsIfaceLType . getBangType       . unLoc) args)
+		 (map (hsStrictMark . getBangStrictness . unLoc) args)
+		 flds
+  where
+    (args, flds) = case details of
+			PrefixCon args -> (args, [])
+			InfixCon a1 a2 -> ([a1,a2], [])
+			RecCon fs      -> (map snd fs, map (get_occ . fst) fs)
+    get_occ lname = rdrNameOcc (unLoc lname)
+
+hsStrictMark :: HsBang -> StrictnessMark
+-- Warning: in source files the {-# UNPACK #-} pragma (HsUnbox) is a request
+-- 	    but in an hi-boot file it's interpreted as the Truth!
+hsStrictMark HsNoBang = NotMarkedStrict
+hsStrictMark HsStrict = MarkedStrict
+hsStrictMark HsUnbox  = MarkedUnboxed
+
 hsIfaceName rdr_name	-- Qualify unqualifed occurrences
 				-- with the module name
   | isUnqual rdr_name = LocalTop (rdrNameOcc rdr_name)

ghc/docs/users_guide/separate_compilation.sgml

@@ -948,6 +948,32 @@ newtype GHC.IOBase.IO a
 	  <literal>instances</literal> or derive them automatically.
 </para>
 	</listitem>
+
+<listitem> <para>For <literal>data</literal> or <literal>newtype</literal> declaration, you may omit all
+the constructors, thus:
+<ProgramListing>
+module A where
+  data TA
+</ProgramListing>
+      (You must write all the type parameters, but omit the
+      '=' and everything that follows it.)  In a <emphasis>source</emphasis> program
+	  this would declare TA to have no constructors (a GHC extension: see <xref linkend="nullary-types">),
+	  but in an hi-boot file it means "I don't know or care what the construtors are".
+	    This is the most common form of data type declaration, because it's easy to get right.</para>
+	  <para>
+	  You <emphasis>can</emphasis> also write out the constructors but, if you do so, you must write
+	  it out precisely as in its real definition. 
+	    It is especially delicate if you use a strictness annotation "!", 
+	  with or without an <literal>{-# UNPACK #-}</literal> pragma.  In a source file
+	  GHC may or may not choose to unbox the argument, but in an hi-boot file it's
+	  assumed that you express the <emphasis>outcome</emphasis> of this decision.  
+	    (So in the cases where GHC decided not to unpack, you must not use the pragma.)
+	    Tread with care.</para>
+	</listitem>
+
+<listitem> <para>For <literal>class</literal> declaration, you may not specify any class
+operations.  We could lift this restriction if it became tiresome.</para>
+</listitem>
       </itemizedlist>
 
       <para>Notice that we only put the declaration for the newtype
@@ -955,18 +981,6 @@ newtype GHC.IOBase.IO a
       not the signature for <Function>f</Function>, since
       <Function>f</Function> isn't used by <literal>B</literal>.</para>
 
-      <para>If you want an <literal>hi-boot</literal> file to export a
-      data type, but you don't want to give its constructors (because
-      the constructors aren't used by the SOURCE-importing module),
-      you can write simply:</para>
-
-<ProgramListing>
-module A where
-data TA
-</ProgramListing>
-
-      <para>(You must write all the type parameters, but leave out the
-      '=' and everything that follows it.)</para>
     </sect2>