[cvs-nhc98] patch applied (hat): Improve pattern-parsing to return more informative error messages.

[Malcolm Wallace]

Tue Feb 11 04:04:28 PST 2003  malcolm
  * 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.)

    M ./src/hattools/HatObserve.hs -18 +19
    M ./src/hattools/Pattern.hs -5 +8