March 2003 - Haskell - Haskell.org

GUI for Windows
by Markus.Schnell＠infineon.com 03 Mar '03

03 Mar '03

What User Interface Library would you recommend for use under Windows? I tried FranTk but it crashes as soon as I run the display function (under hugs) and with ghc it won't even compile (I already tinkered with the makefiles, so finally I could make the package, but then the demos won't compile). Any ideas, suggestions? Markus

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The Revised Haskell 98 Report
by Simon Peyton-Jones 03 Mar '03

03 Mar '03

Folks I am holding in my hands the first copy of the Haskell 98 Report to roll off the presses at Cambridge University Press. It looks great. And it has a copyright notice that says "It is intended that this Report belong to the entire Haskell community...", just as the online version does. It's in CUP's catalogue here: http://titles.cambridge.org/catalogue.asp?isbn=0521826144 Order your copy now (£35)! Not only is a physical copy useful, but CUP's agreement to the rather unique copyright terms deserves our support. Simon

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How to make Parser explicitly "fail"?
by L BB 03 Mar '03

03 Mar '03

Hi, there. I am glad to join Haskell community. :) Here I have a question about Parser: how to make a parser explicitly "fail"? My question arises from the syntax below: <statement>::=<keyword><seperator><variable> <keyword>::="define" <seperator>::=':' <variable>::=identifier other than <keyword> <identifier>::=(<letter>)+ <letter>::=a..z|A..Z Now I am thinking of writing a Parser for variable. My thought is: variable::Parser String variable = do s<-identifier if not (s=="define") then return s else --let parser fail I will be very happy if there is some mechanism to implement the "else" branch, for I have thought of it for long. :) __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/

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How to catch and error message and how to make it create unix files instead of dos files??
by Alexandre Weffort Thenorio 02 Mar '03

02 Mar '03

I am trying to write a small software to take info from one file and write it into another file. The problem is that when I don't give any input I get the normal haskell nosuchfile error message but I want to give my own error message. I am a newbie, how can I do that? Also I need the file that is gonna be created (A text file), to be created in UNIX type and not as a DOS file type, how can I do that? I am using ghc to compile on Windows. Here is the main code main :: IO() main = do args <- getArgs codes <- codes args conax <- readconax "conax.txt" makeIrdFile (lines codes) (lines conax) --Read input file------------------------------------ codes :: [String] -> IO[Char] codes [] = return "" codes (x:xs) = do first <- readFile x return first --Read Inbuilt file--------------------------------- readconax file = do list <- readFile file return list

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How to force UNIX text files as output instead of DOS text files??
by Alexandre Weffort Thenorio 02 Mar '03

02 Mar '03

I am working on a small program which writes a text file but I need this file to be in UNIX format and as it is a Windows program I am compiling it, the output file tends to be in DSO format. Is there anyway that I can force it to create the file in UNIX format??? Best Regards NooK

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Re: int to float problem
by Zdenek Dvorak 01 Mar '03

01 Mar '03

Hello, [snip] >Try > >intToFloat :: Int -> Float >intToFloat n = fromInteger (toInteger n) [snip] >Use the Prelude function realToFrac. it sometimes happens to me that I must spend some time browsing prelude to devise somethink like this; it might be useful to have a library for this, that would define class Coerce a b where coerce :: a->b of course this cannot work without multiparametric type classes. Zdenek _________________________________________________________________ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail

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