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The Haskell Cafe
February 2007 - page 1
Modulo-foo equivalence classes in Haskell? (3 Replies)
Diego Navarro — 117031559501 Feb 2007*
Watching the questions go by in #haskell, a still fuzzy but possibly pregnant idea popped up in my mind. Someone needed a nubBy function that returned...
Pavel Rozenblioum — 117032256001 Feb 2007
Hi, I am trying to compile the GLR examples from Happy 1.16, but I get the message that I am missing the "data" package. Where can I downloa...
Justin Bailey — 117034294101 Feb 2007*
In "The Monad.Reader - Issue 6", that just came out, there is a really interesting article that uses a "circular" technique to imp...
Steve Downey — 117035997001 Feb 2007
The 70's and early 80's were very different in terms of information propagation. I really miss some the journals available back then, because ...
Alistair Bayley — 117039740602 Feb 2007
We are pleased to announce a new release of Takusen. There are a large number of changes and bug-fixes: - Oracle support for processing cursors return...
Let's welcome the Ruby hackers! (4 Replies)
Donald Bruce Stewart — 117039764002 Feb 2007*
As seen here, reports from 'Rails Edge': http://notes-on-haskell.blogspot.com/2007/01/...More from the same guy: http://notes-on-haskell.blogs...
snd and tuples of various sizes... (3 Replies)
Tim Newsham — 117040588402 Feb 2007*
This seems to make using tuples of various sizes easier (and can also be applied to non-tuples). I think it more closely matches how I describe someth...
Array copy performance (2 Replies)
Chris Kuklewicz — 117040925002 Feb 2007*
Hi, I am trying to improve the memory usage of regex-tdfa and I wanted to ask an array question. If I have two identical STUArrays (same type and boun...
Boost equivalent (8 Replies)
John Ky — 117041357502 Feb 2007*
Hi, Does the Haskell community have an equivalent to C++ community's Boost project with the aim of writing libraries for the eventual inclusion in...
Joel Reymont — 117041486702 Feb 2007*
Folks, Allegro Common Lisp has AllegroCache [1], a database built on B-Trees that lets one store Lisp objects of any type. You can designate certain s...
Become a GHC build slave! (1 Reply)
Simon Marlow — 117042749902 Feb 2007*
Thanks largely to Ian Lynagh, GHC now has a BuildBot infrastructure to automate nightly builds on multiple platforms. This replaces the old set of she...
"Write Yourself a Scheme in 48 Hours" (3 Replies)
Shannon -jj Behrens — 117042993502 Feb 2007*
I'm going through the "Write Yourself a Scheme in 48 Hours" <http://halogen.note.amherst.edu/~jdtang/schem...> tutorial. I like it...
It matters how Type Synonyms are defined? (3 Replies)
Bryan Burgers — 117047005003 Feb 2007*
Today, I was plugging away on a program and I ran into a problem. It seems that ErrorT can or can not take a type synonym as its monad, depending on h...
(a -> [b]) vs. [a -> b] (7 Replies)
Chad Scherrer — 117048723503 Feb 2007*
Are (a -> [b]) and [a -> b] isomorphic? I'm trying to construct a function f :: (a -> [b]) -> [a -> b] that is the (at least one-si...
Brian Hulley — 117050690503 Feb 2007
Hi, Following a recent thread on the Haskell' mailing list about the nusiance of having to deal with commas in tuples (when cutting and pasting th...
The usage of runghc ? (1 Reply)
keepbal — 117053612003 Feb 2007*
I tried to install haskell-fastcgi ( http://www.cs.chalmers.se/~bringert/darcs/has... ).Preprocessing library fastcgi-2006.10.9... FastCGI.hsc:50:21: ...
Alternate instance Show (Maybe a)? (4 Replies)
Sergey Zaharchenko — 117056692804 Feb 2007*
Hello list, Suppose I want show Nothing to return "", and show (Just foo) return show foo. I don't seem to be able to. Looks like I eith...
Space Leak Help (12 Replies)
Dominic Steinitz — 117059003204 Feb 2007*
I have re-written SHA1 so that is more idiomatically haskell and it is easy to see how it implements the specification. The only problem is I now have...
Suggestions for a hReadUntilStr implementation (5 Replies)
Matt Revelle — 117059721104 Feb 2007*
Hey there, A few weeks back I was thinking of writing a Haskell program that automated a telnet session. One function that could be useful is a hReadU...
Another Space Leak (1 Reply)
Dominic Steinitz — 117059829104 Feb 2007*
Many thanks for the help on the original space leak which is now fixed -see the function pad below and test runs in small constant space. However, tha...
C Rodrigues — 117061077204 Feb 2007
...
Strange behaviour with writeFile (4 Replies)
C.M.Brown — 117061315304 Feb 2007*
Hi, I am observing some rather strange behaviour with writeFile. Say I have the following code: answer <- AbstractIO.readFile "filename...
Win32 help please (3 Replies)
John Ky — 117063040604 Feb 2007*
Hi, I'm interested in writing accessing some Win32 functions not available from GHC.Then tried to compile it like this: # hsc2hs mywin32.hsc # ghc...
Connected! (4 Replies)
Bulat Ziganshin — 117063275904 Feb 2007*
Hello haskell-cafe, i've just got ADSL connection here! it's slow (64k) and not cheap, but at least it is completely different from dial-up i...
mixing wxhaskell state and file io (4 Replies)
Martin DeMello — 117066864405 Feb 2007*
I'm having a lot of trouble mixing file io and wxhaskell's varCreate/Get/Set functions. I have functions readWords :: String -> IO WordMap ...
how to calculate the sum of list of lists? (4 Replies)
Miranda Kajtazi — 117067676405 Feb 2007*
Help, How to calculate the sum of list of lists in Haskell? Please help me, Miranda...
C Rodrigues — 117068173205 Feb 2007
I'd like to hear what tips and techniques you guys have for avoiding space leaks. I understand the basic techniques to force evaluation of closure...
Miranda Kajtazi — 117068175205 Feb 2007*
Hi, Thanx to all for the previous hints how to solve and write the function to calculate the sum of a list of lists. Now I need to know how to remove ...
Bahtijar Vogel — 117068383505 Feb 2007*
Hi, How am I supposed to use infinite lists to define the list of all negative integers?...
Timezone Database Library (1 Reply)
Martin Percossi — 117069254905 Feb 2007*
Hello, is there a haskell library that provides facilities to read and use the tzfile format [1], or equivalent in Windows? TIA Martin [1] http://www....
Thomas Hartman — 117069353005 Feb 2007*
haskellers, I'm contemplating returning to school after a decade as a worker bee, and almost that long as a worker bee doing computer consulting /...
A function callable from C (4 Replies)
John Ky — 117071310505 Feb 2007*
Hi, The following code works:ServiceMainClosure) But the following doesn't:ServiceMainClosure) System\Win32\Service.hsc:108:8: parse error on inpu...
List operation question (8 Replies)
Eric Olander — 117072213206 Feb 2007*
Hi, I'm still somewhat new to Haskell, so I'm wondering if there are better ways I could implement the following functions, especially shiftl:...
How is laziness defined? (12 Replies)
TJ — 117072442906 Feb 2007*
I would think that with 100% laziness, nothing would happen until the Haskell program needed to output data to, e.g. the console. Quite obviously that...
strict bytestring fun (2 Replies)
Donald Bruce Stewart — 117073182906 Feb 2007*
High performance strings on the shootout: http://shootout.alioth.debian.org/gp4/benchma... interesting alternative programs 0.5 Haskell GHC #5 1.29 90...
Function Composition (1 Reply)
Chris Witte — 117073770506 Feb 2007*
Can anyone explain why Shape.Polygon would have a different type to (Shape).Polygon, I thought the brackets would be redundant. Here is the output fro...
Generalizing three programs (5 Replies)
Andrew Wagner — 117074963806 Feb 2007*
Hi everyone, I've got an interesting problem here I'm trying to solve. Actually, I've got several problems which seem to have a very simil...
Bulat Ziganshin — 117076828106 Feb 2007*
Hello haskell-cafe, this seems like a comprehensive overview of FP facilities in C# 3.0: http://blogs.msdn.com/madst/archive/2007/01/2......
Trouble representing a set of flags (2 Replies)
Stefan O'Rear — 117078672706 Feb 2007*
I have a structure: data Attr = Attr { fg :: !Color, bg :: !Color, bold :: !Bool, blink :: !Bool, rv :: !Bool, halfBright :: !Bool, underline :: !Bool...
External Core (4 Replies)
Ricky Barefield — 117081867107 Feb 2007*
Dear All,For the last year I've been working on a program to translate between Haskell and Java. Originally this was for my third year dissertatio...
haskell and releasing resources (12 Replies)
Fawzi Mohamed — 117084798607 Feb 2007*
I am just coming to haskell, and I wrote a simple command to get some input from a pdf file I just wanted the output of the command so I did something...
nested maybes (29 Replies)
Martin DeMello — 117087353007 Feb 2007*
I have a Data.Map.Map String -> (Layout, [String]) as follows: type Anagrams = [String] type Cell = (Layout, Anagrams) type WordMap = Map.Map Strin...
Importance of MonadRandom (3 Replies)
Yitzchak Gale — 117087371507 Feb 2007*
I would like to point out the importance of Cale Gibbard's MonadRandom, beyond what is currently mentioned on its wiki page: http://www.haskell.or...
Steve Downey — 117087393207 Feb 2007
I think I finally have it. Partial application is taking a function of N parameters, binding a value to one of them, and turning it into a function of...
still wrestling with io (2 Replies)
Martin DeMello — 117093514508 Feb 2007*
Code here: http://zem.novylen.net/anagrid.html I've got an instance of IO appearing unexpectedly and I can't figure out where from. It throws ...
Monolithic module tool (1 Reply)
Chad Scherrer — 117095556108 Feb 2007*
Maybe a year or so ago, I came across a tool for Haskell that takes a collection of modules, does some name-mangling, and gives a single module that o...
Portable implementation of unsafeCoerce (2 Replies)
Alfonso Acosta — 117096033808 Feb 2007*
Hi all, Reading the sources of Lava (a Haskell Hardware Description DSL) I run into this definition ... unsafeCoerce :: a -> b unsafeCoerce a = uns...
weak references & caches (1 Reply)
Thomas Conway — 117097367708 Feb 2007*
Hi All, I'm hacking some (external) B-Tree code, and amongst the numerous interesting problems I've come up against[*], is to do with managing...
Random numbers without IO (1 Reply)
Dougal Stanton — 117105192809 Feb 2007*
Well, nobody likes tainting their beautiful pure code with IO, so ICheers, D. [1] <http://xkcd.com/c221.html...
Bulat Ziganshin — 117108257510 Feb 2007
Hello, i'd a discussion in russian programmer's forum (rsdn.ru) about haskell and learning it. one interesting point was that imperative progr...