[Haskell] mini-Announce: update to Happy-GLR templates

P.C.Callaghan p.c.callaghan at durham.ac.uk
Fri Aug 26 05:53:17 EDT 2005


I've recently checked in modified template code for the GLR mode of Happy.
It handles densely ambiguous grammars a lot better, although may be slower
on more reasonable grammars, particularly if empty productions are heavily
used (eg for gap rules in biological sequence grammars).

For example, it can parse "E -> E + E | i" on sentences with 201 tokens in
a small number of seconds; the previous version could not handle more than
41 in reasonable time.

You can get the code from CVS, or download the files via the following:

There's still plenty of room for further speed improvements. Contact me if
interested. Further information can be found at:


Dr Paul Callaghan       (Lecturer)      Email: P.C.Callaghan at durham.ac.uk
Dept of Computer Science, Durham        http://www.dur.ac.uk/p.c.callaghan

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