http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/ Perl, Haskell, stuff Fri, 30 Jul 2010 18:16:16 +0000 http://wordpress.org/?v=2.5.1 http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-697 G. Wade Johnson Sat, 31 Jan 2009 23:42:17 +0000 http://greenokapi.net/blog/?p=158#comment-697 A simpler change to fix the "/a" and "/aa" problem is to modify the regular expression in the longest method to /^\Q$last\E(?:\/|$)/ That way it only matches a full directory name or the whole string. Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
]]> http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-689 More longest paths, and sick folds. - Just another lambdabananacamel, Fri, 30 Jan 2009 22:08:14 +0000 http://greenokapi.net/blog/?p=158#comment-689 [...] paths, and sick folds. 31Jan2009 Filed under: Uncategorized Author: osfameron This week's simple longest path exercise seems to have had more mileage in it than I expected. Thanks to everyone's comments and [...] Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
]]> http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-685 Jedai Fri, 30 Jan 2009 17:47:15 +0000 http://greenokapi.net/blog/?p=158#comment-685 Note that System.FilePath has convenient functions to explode and recompose a path, so you could write : longest6 :: [String] -> [String] longest6 = map joinPath . uniqBy' isPrefixOf . sort . map splitDirectories Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
]]> http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-672 Anon Tue, 27 Jan 2009 21:01:28 +0000 http://greenokapi.net/blog/?p=158#comment-672 ### Ocaml: let longest l = let sl = List.sort String.compare l in let isPrefixOf a b = try if ((String.compare a (String.sub b 0 (String.length a))) == 0) then true else false with Invalid_argument e -> false in List.rev (List.fold_left (fun al b -> let a = List.hd al in if (isPrefixOf a b) then b::(List.tl al) else b::al ) [(List.hd sl)] sl) Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
]]> http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-669 x Tue, 27 Jan 2009 17:57:50 +0000 http://greenokapi.net/blog/?p=158#comment-669 of course there is a bug here - run it on this testcase: ["/a", "/aa", "/aaa", "/aaaa"] Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
]]> http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-666 Will Boyce Tue, 27 Jan 2009 12:44:30 +0000 http://greenokapi.net/blog/?p=158#comment-666 ### Python: l = ["/foo", "/qux/wibble", "/foo/bar/baz", "/qux", "/foo/bar"] l = sorted(l, reverse=True) r = [] for p in l: if not any(re.startswith(p) for re in r): r.append(p) ### Erlang: start() -> Paths = lists:reverse(lists:sort(["/foo", "/qux/wibble", "/foo/bar/baz", "/qux", "/foo/bar"])), Fun = fun(X, Acc) -> case lists:any(fun(E) -> case string:str(E, X) of 0 -> false; _ -> true end end, Acc) of false -> lists:merge(Acc, [X]); true -> Acc end end, lists:foldl(Fun, [], Paths). Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
]]> http://greenokapi.net/blog/2009/01/27/theres-the-nub-snippet-in-perl-and-haskell/#comment-665 Programmer Tue, 27 Jan 2009 08:58:12 +0000 http://greenokapi.net/blog/?p=158#comment-665 "Penfold suggested splitting on "/" into a multilevel hash," Ugh, one of the absolute worst things with perl: nonsensical handling of nested data structures. Every other modern language does this *vastly* better. One of the many reasons Perl is obsolete. Warning: preg_replace_callback() [function.preg-replace-callback]: Unknown modifier '|' in /var/www/blog/wp-content/plugins/text-control/text-control/markdown.php on line 766
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