[Haskell] Re: manipulating untyped lambda-calculus in Haskell
ccshan at post.harvard.edu
Sat Apr 30 15:13:38 EDT 2005
Vivian McPhail <vivian.mcphail at paradise.net.nz> wrote in article <001301c54d6c$ba44b980$0301a8c0 at intranet> in gmane.comp.lang.haskell.general:
> It seems that I must be missing something? Is there a more elegant
> way of doing this?
Check out the "generalized algebraic data types" feature (GADT, one of
its many names), now available in GHC. One classical example of its use
is to write type-safe interpreters similar to your NL parser.
Edit this signature at http://www.digitas.harvard.edu/cgi-bin/ken/sig
Science operates according to a law of conservation of difficulty. The simplest
questions have the hardest answers; to get an easier answer, you need to ask
a more complicated question. -- George Musser. Color Madness. Oddball maps can
require more than four colors. Sci. Am., January 2003.
More information about the Haskell