tag:blogger.com,1999:blog-11295132.post378632905500461368..comments2015-11-05T00:40:24.898-08:00Comments on A Neighborhood of Infinity: A Small Combinatorial LibraryDan Piponihttps://plus.google.com/107913314994758123748noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-11295132.post-5101205888687250062010-07-01T15:37:13.603-07:002010-07-01T15:37:13.603-07:00porges,
Everyone interested in this stuff probabl...porges,<br /><br />Everyone interested in this stuff probably should read: http://byorgey.wordpress.com/2010/04/07/functional-pearl-on-combinatorial-species/<br /><br />And http://www.math.upenn.edu/~wilf/DownldGF.htmlsigfpehttp://www.blogger.com/profile/08096190433222340957noreply@blogger.comtag:blogger.com,1999:blog-11295132.post-67257449902007570612010-07-01T15:32:26.794-07:002010-07-01T15:32:26.794-07:00I like how this:
> list x = 1/(1-x)
Is deriva...I like how this:<br /><br />> list x = 1/(1-x)<br /><br />Is derivable from:<br /><br />> [x] = [] | x : [a]<br />> ( == list x = 1 + x * list x )<br /><br />It seems to me, that if `log` has type `exp x -> x`, and `exp x` is a set, then `log` is some kind of a choice function.<br /><br />Is there anything deeper going on here? Can you recommend any extra reading?porgeshttp://porg.es/blognoreply@blogger.comtag:blogger.com,1999:blog-11295132.post-12865798736550177892007-11-13T15:56:00.000-08:002007-11-13T15:56:00.000-08:00Although I've never used Maple, I think I got the ...Although I've never used Maple, I think I got the idea for this library from seeing snippets of Maple code on the web.sigfpehttp://www.blogger.com/profile/08096190433222340957noreply@blogger.comtag:blogger.com,1999:blog-11295132.post-9545206714636841532007-11-13T15:53:00.000-08:002007-11-13T15:53:00.000-08:00blogger.com seems to chew up my spaces. I've alrea...blogger.com seems to chew up my spaces. I've already tried to fix this once but if the code still doesn't work, simply insert extra spaces at the beginning of each line that fails to compile. Just keep inserting spaces until each line does compile :-)sigfpehttp://www.blogger.com/profile/08096190433222340957noreply@blogger.comtag:blogger.com,1999:blog-11295132.post-75823237200239612402007-11-13T15:47:00.000-08:002007-11-13T15:47:00.000-08:00Hrm, your post isn't working in ghci, which compla...Hrm, your post isn't working in ghci, which complains about the second line in the definition of inverse, invert, and sqrt' (and probably others). The underscores seem to be causing the difficulty; do I need to use a special GHC flag? I'm running 6.6.1 on Ubuntu Gutsy.<BR/><BR/>Also, your DSL reminds me of Maple's <A HREF="http://www.google.com/search?q=maple+combstruct" REL="nofollow">combstruct</A> <BR/>package, which generates combinatorial structures using grammars. <BR/><BR/>And finally, I realized example 9 isn't what I need -- your pairs are ordered, and I don't want that. It should be very simple to change that, though.Danhttp://www.blogger.com/profile/14610452548397350629noreply@blogger.comtag:blogger.com,1999:blog-11295132.post-8813931457185705992007-11-11T19:07:00.000-08:002007-11-11T19:07:00.000-08:00Wow! This is great. I've been interested in Haskel...Wow! This is great. I've been interested in Haskell and have been learning it, but until now I haven't found a way to directly apply it to my current research on the combinatorics of matchings. Your example 9 is just what I need.<BR/><BR/>Thanks!Danhttp://www.blogger.com/profile/14610452548397350629noreply@blogger.com