-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 apfelmus wrote:
Isaac Dupree wrote:
Mark T.B. Carroll wrote:
I've been playing with Text.Parsers.Frisby to see how it stacks against other options and, while it's been great so far, I am finding that I can't encode a grammar where what's acceptable depends on what's already been parsed in some nontrivial way. [...] Is this supposed to not be possible in Frisby, or (quite likely) am I missing something that allows me to? It's intentionally impossible. Frisby uses a dynamic programming approach that crucially depends on the fact that the grammar in question is context-free (actually something related, but the effect is the same). Is that dependence crucial? What if it gained Monad operations that just weren't intended to be used very often, and maybe locally harmed
apfelmus wrote: performance a little where they are used?
Now that you ask, I become unsure
Luckily, Haskell's laziness means that doing an extra "postprocessing pass" doesn't necessarily yield two traversals requiring the whole file to be stored in memory, nor worse hacks. (For grammars that aren't too wild / sequential) Isaac -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGXLcBHgcxvIWYTTURArCuAJ9mR8HFqiRNT7teWjhvAtRwXYgjfwCgu7hi YEXGLGvMVHQwlZpfxTDi0FI= =b3Q7 -----END PGP SIGNATURE-----