[cvs-nhc98] Improve pattern-parsing to return more informative error m

[Malcolm Wallace]

malcolm: Tue Feb 11 13:04:29 CET 2003

Update of /usr/src/master/nhc/src/hat/tools
In directory hinken:/tmp/cvs-serv29096

Modified Files:
	HatObserve.hs Pattern.hs 
Log Message:
Improve pattern-parsing to return more informative error messages.
Also, correct the omission of pattern-matching on named field exprs.
(Unfortunately, the parser still cannot read a field pattern typed
by the user, but at least you now get an error rather than 'no match',
and the alterative pattern (C _) now works.)