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diff --git a/ghc/compiler/reader/PrefixSyn.lhs b/ghc/compiler/reader/PrefixSyn.lhs
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+%
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+%
+\section[PrefixSyn]{``Prefix-form'' syntax}
+
+This module contains an algebraic data type into which a prefix form
+string from the current Haskell parser is converted.  Given in an
+order that follows the \tr{Prefix_Form} document.
+
+\begin{code}
+#include "HsVersions.h"
+
+module PrefixSyn (
+	RdrBinding(..),
+	RdrId(..),
+	RdrMatch(..),
+	RdrTySigPragmas(..),
+	SigConverter(..),
+	SrcFile(..),
+	SrcFun(..),
+	SrcLine(..),
+
+	readInteger
+    ) where
+
+import AbsSyn
+import ProtoName	( ProtoName(..) ) -- .. is for pragmas only
+import Outputable
+import Util		-- pragmas only
+
+type RdrId   = ProtoName
+type SrcLine = Int
+type SrcFile = FAST_STRING
+type SrcFun  = FAST_STRING
+\end{code}
+
+\begin{code}
+data RdrBinding
+  = RdrNullBind
+  | RdrAndBindings	RdrBinding RdrBinding
+
+  | RdrTyData		ProtoNameTyDecl
+  | RdrTySynonym	ProtoNameTyDecl
+  | RdrFunctionBinding	SrcLine [RdrMatch]
+  | RdrPatternBinding	SrcLine [RdrMatch]
+  | RdrClassDecl 	ProtoNameClassDecl
+  | RdrInstDecl 	( FAST_STRING{-original  module's name-} ->
+			  FAST_STRING{-informant module's name-} ->
+			  Bool{-from here?-} ->
+			  ProtoNameInstDecl )
+  | RdrDefaultDecl	ProtoNameDefaultDecl
+  | RdrIfaceImportDecl	IfaceImportDecl
+
+			-- signatures are mysterious; we can't
+			-- tell if its a Sig or a ClassOpSig,
+			-- so we just save the pieces:
+  | RdrTySig		[ProtoName]	    -- vars getting sigs
+			ProtoNamePolyType   -- the type
+			RdrTySigPragmas	    -- val/class-op pragmas
+			SrcLoc
+
+  -- user pragmas come in in a Sig-ish way/form...
+  | RdrSpecValSig   	[ProtoNameSig]
+  | RdrInlineValSig 	ProtoNameSig
+  | RdrDeforestSig 	ProtoNameSig
+  | RdrMagicUnfoldingSig ProtoNameSig
+  | RdrSpecInstSig  	ProtoNameSpecialisedInstanceSig
+  | RdrAbstractTypeSig  ProtoNameDataTypeSig
+  | RdrSpecDataSig   	ProtoNameDataTypeSig
+
+data RdrTySigPragmas
+  = RdrNoPragma
+  | RdrGenPragmas	ProtoNameGenPragmas
+  | RdrClassOpPragmas	ProtoNameClassOpPragmas
+
+type SigConverter = RdrBinding {- a RdrTySig... -} -> [ProtoNameSig]
+\end{code}
+
+\begin{code}
+data RdrMatch
+  = RdrMatch SrcLine SrcFun ProtoNamePat [(ProtoNameExpr, ProtoNameExpr)] RdrBinding
+				       -- (guard,         expr)
+\end{code}
+
+Unscramble strings representing oct/dec/hex integer literals:
+\begin{code}
+readInteger :: String -> Integer
+
+readInteger ('-' : xs)	     = - (readInteger xs)
+readInteger ('0' : 'o' : xs) = chk (stoo 0 xs)
+readInteger ('0' : 'x' : xs) = chk (stox 0 xs)
+readInteger ['0']	     = 0    -- efficiency shortcut?
+readInteger ['1']	     = 1    -- ditto?
+readInteger xs		     = chk (stoi 0 xs)
+
+chk (i, "")   = i
+chk (i, junk) = panic ("readInteger: junk after reading:"++junk)
+
+stoo, stoi, stox :: Integer -> String -> (Integer, String)
+
+stoo a (c:cs) | is_oct c  = stoo (a*8 + ord_ c - ord_0) cs
+stoo a cs                 = (a, cs)
+
+stoi a (c:cs) | isDigit c = stoi (a*10 + ord_ c - ord_0) cs
+stoi a cs                 = (a, cs)
+
+stox a (c:cs) | isDigit c = stox (a_16_ord_c - ord_0)      cs
+	      | is_hex  c = stox (a_16_ord_c - ord_a + 10) cs
+	      | is_Hex  c = stox (a_16_ord_c - ord_A + 10) cs
+	      where a_16_ord_c = a*16 + ord_ c
+stox a cs = (a, cs)
+
+is_oct c = c >= '0' && c <= '7'
+is_hex c = c >= 'a' && c <= 'f'
+is_Hex c = c >= 'A' && c <= 'F'
+
+ord_ c = toInteger (ord c)
+
+ord_0, ord_a, ord_A :: Integer
+ord_0 = ord_ '0'; ord_a = ord_ 'a'; ord_A = ord_ 'A'
+\end{code}