Block comments in Haskell (PS).

[Kent Karlsson <kent>]

Original-Via: uk.ac.ukc; Fri, 14 Sep 90 10:05:05 BST
From: Kent Karlsson <kent>
Date: Fri, 14 Sep 90 10:49:14 +0200
To: haskell@cs.glasgow.ac.uk
Subject: Block comments in Haskell (PS).
Original-Sender: kent%se.chalmers.cs@sunic.sunet.se
Sender: haskell-request@cs.glasgow.ac.uk


OOPS, still a glitch...

I wrote (wrongfully!)

       ncomment -> {- {whitespace|string|{any}                                   } -}
       			                      { {any}( " | {- | -- | -} ){any} }


in the "first alternative", but that still makes e.g. "{- {- -}" and even "{- -} -}"
into *complete*  ncomments.  It should be the following productions instead:

	ncomment -> {- junk {(whitespace|string) junk} -}
       			                     
	junk     -> {any}
       	                 { {any}( " | {- | -- | -} ){any} }

(where the "{" and "}" in "{-" and "-}" are not meta-characters)

(Sorry for not discovering this glitch yesterday...  The "second alternative"
 should *not* be changed, though the two alternatives (now) can be made to look more
 alike by moving "white" around.  So the "first alternative" could look like this:

	ncomment   -> {- junk {(comment|ncomment|string) junk} -}
       			                     
	junk       -> {any | white}
       	                           { {any | white}( " | {- | -- | -} ){any | white} }

	white      -> newline | space | tab | vertab | formfeed
	
	whitestuff -> white | comment | ncomment
)


				/kent k