RE: character syntax
itz All this taken together, I mean, _really_, is the lexical itz structure of Haskell a botch, or what? Jon No. Innovative. All the problems described in this thread reflect Jon unwarranted assumptions inherited in emacs. It's plainly possible Jon to parse Haskell, and not hard either. First, parsing of a complete program (eg. by a compiler) is quite different from parsing a buffer that is being edited by a human. The latter is hard, even for fairly well-specified languages. Irregularities only make it harder. For syntax highlighting you only need to lexically analyse the buffer, not parse it. Haskell's lexical syntax is parseable by regular expressions, which means it shouldn't be hard to plug a syntax highlighter for Haskell into just about any editor. I don't understand why you say that parsing a buffer being edited by a human is hard - perhaps doing incremental lexing is slightly harder than whole-file lexing, but not that much harder. The state of a Haskell lexer can be represented with a little trickery by an integer, so it isn't hard to cache the lexer's state at the beginning of each line. I did this once as an experiment when I added Haskell syntax highlighting to one of the KDE editors (I forget which). The problem is not Haskell, it's emacs. Emacs's syntax highlighting has fairly deeply-wired-in assumptions about C-like languages (eg. last I looked you still couldn't support nested comments properly in font-lock). Cheers, Simon ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: character syntax
On Friday 08 February 2002 14:35, Ketil Z. Malde wrote: Jorge Adriano [EMAIL PROTECTED] writes: Haskell looks nice... Isabell looks beautiful :-) I'm not familiar with Isabell, but aren't we comparing apples and oranges here? E.g. you can prettify .lhs pretty nicely with one of the LaTeX packages available. Well yes :-) You said Personally, I think the Haskell syntax is beautiful, and in my answer I talked about the way it looked on Xemacs, not the syntax. But not sure if we are talking about the same thing here, how do you prettify the .lhs files? Are you talking about the dvi you get in the end or the way it looks while editing the code? And no, I don't have the time to do something better myself now, so I'll just stick to it :-) If somebody would come up with a mode that used lambdas and arrows to render things nicely in my editor, I wouldn't mind. But I don't think the benefit for me would be great enough to justify the effort (I'm not much of a lisp hacker). I wouldn't mind either. Everything looks really nice, making your code really easy to read, it's not just the greek leters, the 'forall's, the arrows '=', the 'and's and the 'or's. But the Isabell/Isar/Proof General (which I haven't used in a long time) mode had more to it than just that. The menus were pretty good, buttons (with icons) for some commands... it turns Xemacs into a very nice GUI for isabelle. J.A. ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: efficiency question
I'd say that's because in the second case you also got to apply the (,), besides the (+)/(-) constructor during the transversing... Am I right? opss... I meant to write: the (,) constructor besides the (+)/(-)... J.A. ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: efficiency question
(moved to haskell-café) I ran Hal's code on my computer, and with test2 I get a stack overflow (so I had to use +RTS option for it to finish). test1 does not overflow stack (of standard size, I mean without +RTS). Which implies that test2 uses more stack space than test1. why would it use more stack if not because of laziness? konst -Original Message- From: Hal Daume III [mailto:[EMAIL PROTECTED]] Sent: Friday, February 08, 2002 4:35 PM To: Jorge Adriano Cc: Konst Sushenko; [EMAIL PROTECTED] Subject: Re: efficiency question I agree that it's the overhead of (,), but I don't see why there would be any overhead for doing this. -- Hal Daume III Computer science is no more about computers| [EMAIL PROTECTED] than astronomy is about telescopes. -Dijkstra | www.isi.edu/~hdaume On Sat, 9 Feb 2002, Jorge Adriano wrote: On Friday 08 February 2002 23:52, Hal Daume III wrote: I've tried using a strict fold: foldl' f a [] = a foldl' f a (x:xs) = (foldl' f $! f a x) xs but that has no effect (or minimal effect). That wouldn't work even if if laziness is the problem because that would only cause the elements of the list to be evaluated to head normal form, the elements of the pair would not be evaluated so you'd have a 'suspension of (minus and plus) operations'. instead of (\x (a,b) - (x+a,x-b)) try (\x (a,b) - (((,) $! x-a)$! x-b) ) I just noticed that you were the one who sent me the DeepSeq module. This is the kind of place where I want to use it. Instead of $!, try $!!. And Konst Sushenko wrote: My guess is that it is due to the laziness of the addition/subtraction in (,) Seems to me like lazyness is not the right guess because both functions Hall first posted were lazy. So I think it's just the overhead of applying (,) besides (+) and (-) in each step. Do I make sense or am I missing something? J.A. ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
