- Haskell-Cafe - Haskell.org

library for generating HTML and LaTeX
by Henning Thielemann 09 Mar '07

09 Mar '07

We have Text.Html in the standard libraries for generating HTML code. Is there also a library for generating LaTeX code? Or even better: Is there a library which can emit the same document with markup in HTML, LaTeX or a different markup language? Frequently I like to present results of some computations and then I start hacking output for LaTeX and I wonder if there is a simpler solution.

2 2

Fwd: [Haskell-cafe] Re: Haskell spacing problem.
by Mark Goldman 09 Mar '07

09 Mar '07

Oops, think I didn't send this to cafe, forgive any duplicates please. -mdg ---------- Forwarded message ---------- From: Mark Goldman <bitshifter(a)gmail.com> Date: Mar 9, 2007 8:37 AM Subject: Re: [Haskell-cafe] Re: Haskell spacing problem. To: Frozz <dj_frozz(a)hotmail.com> >From a different angle, are you looking at the text file with a proportional font instead of a fixed width font? With a proportional font each letter takes up a different amount of horizontal space which mucks up most ASCII based formating. -mdg On 3/9/07, Frozz <dj_frozz(a)hotmail.com> wrote: > prettyPrint seems complicated.. > > Dan Mead <d.w.mead <at> gmail.com> writes: > > > > > > > that seems like the "wrong" waycheck out prettyprint in the standard library > > > > On 3/9/07, Frozz < > > dj_frozz <at> hotmail.com> wrote:Hi Haskell ppl,I'm trying to solve a > problem that had been bothering me for a long time. I'm > > trying to create index and display the index in Hugs as well as an output > textfile.Below is my code. In Hugs, the index managed to get displayed well > with nicealignments. However, for the text file, the alignment is off. The > bracket with > > the numbers are messy. I really don't know why this would happen.Desired > output:Anna [1]Ben[2]Shane[3]dispTable :: [([Int], Word)] -> > StringdispTable = unlines . map (\ (num,word) -> word ++ > > take (25 - (length word)) (repeat ' ')++ show num)Did i do sth > wrong? Thanks in > advance._______________________________________________Haskell-Cafe mailing > list > > Haskell-Cafe <at> haskell.orghttp://www.haskell.org/mailman/listinfo/haskell- > cafe > > > > > > > > > > > > _______________________________________________ > > Haskell-Cafe mailing list > > Haskell-Cafe <at> haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > > > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- Our problems are mostly behind us, now all we have to do is fight the solutions. -- Our problems are mostly behind us, now all we have to do is fight the solutions.

1 0

Haskell spacing problem.
by Frozz 09 Mar '07

09 Mar '07

Hi Haskell ppl, I'm trying to solve a problem that had been bothering me for a long time. I'm trying to create index and display the index in Hugs as well as an output text file. Below is my code. In Hugs, the index managed to get displayed well with nice alignments. However, for the text file, the alignment is off. The bracket with the numbers are messy. I really don't know why this would happen. Desired output: Anna [1] Ben [2] Shane [3] dispTable :: [([Int], Word)] -> String dispTable = unlines . map (\ (num,word) -> word ++ take (25 - (length word)) (repeat ' ') ++ show num) Did i do sth wrong? Thanks in advance.

3 3

Distributing a GHC-compiled binary for Macs (x86)
by Arjun Guha 09 Mar '07

09 Mar '07

Hi, I compiled a binary using GHC 6.6 on my Mac (specifically, using ghc --make). This binary seems to depend on the GNU MP framework--I imagine GHC uses it to implement its numeric tower. However, Macs that don't have GHC installed don't seem to have GMP, so I'll guess that it was installed along with the GHC binary. Is there any way to get around this GMP dependency? I expect the binary to be used on Macs that don't have GHC installed. It would be acceptable if I instructed Mac-users to download a binary installer for GMP, but I haven't been able to find one. Any hints or suggestions would be appreciated. Thanks. Arjun

3 3

A different Maybe maybe
by Joachim Breitner 09 Mar '07

09 Mar '07

[Also on http://www.joachim-breitner.de/blog/archives/229-A-different-Maybe-maybe.ht…] Hi, For a while I have been thinking: Isn’t there a way to get rid of the intermediate Maybe construct in a common expression like “fromMaybe default . lookup”. It seems that a way to do that would be to pass more information to the Maybe-generating function: What to do with a Just-Value, and what to return in case of Nothing. This leads to a new definion of the Maybe data type as a function. Later I discovered that this seems to work for any algebraic data type. This is probably nothing new, but was offline at the time of writing, so I didn’t check. This means that this might also be total rubbish. Enjoy. * “Algebraic Data Type Done Differently” (PDF-File) at http://www.joachim-breitner.de/various/FunctionalMaybe.pdf * “Algebraic Data Type Done Differently” (Literate Haskell Source) at http://www.joachim-breitner.de/various/FunctionalMaybe.lhs Comments are appreciated. Greetings from my holidays, Joachim -- Joachim "nomeata" Breitner mail: mail(a)joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C JID: joachimbreitner(a)amessage.de | http://www.joachim-breitner.de/ Debian Developer: nomeata(a)debian.org

10 12

Re: [Haskell] Summer of Code questions
by Malcolm Wallace 08 Mar '07

08 Mar '07

Wolfgang Jeltsch <g9ks157k(a)acme.softbase.org> writes: > First, what organization is Haskell.org? That would be us, right here. Anyone who is interested enough in Haskell to be involved in mailing lists, IRC, distributing library code and tools, whatever. > Is this a real organization, i.e., a legal entity? No. (Unlike e.g. the Apache Foundation.) > Does Haskell.org get the $ 500 for each successful project? > If yes, what does Haskell.org do with this money? Yes, we get the money. Last year, Galois kindly served as the account holder that received the cheque. The mentors involved get to decide what happens to it. I think we are planning to spend last year's on machine/bandwidth for hosting hackage.haskell.org. > Furthermore, the Google Summer of Code FAQ talks about *the* project of a > organization which seems to indicate that each organization has only > one SoC project. The model is that an open-source organisation does indeed usually have one focus, e.g. apache, Linux kernel, GTK, Gnome, Python. But of course there can be smaller tools and focuses within each overarching theme. > What is the project of the Haskell.org organization then? Is this > the general project "The Haskell language plus associated libraries and > tools"? Exactly so. > The FAQ says "Mentor organizations must be organizations or individuals > running an active and viable open source or free software project". Does > this mean that the above-mentioned general project has to be active and > viable (which it is) or that each concrete idea has to be part of an active > and viable project? The former. Decisions about concrete ideas are made collectively by the organisation, and we could certainly decide to go for a relatively immature concrete idea, if it looks both viable and of sufficient value to the community as a whole. > That is, is it allowed to start a new concrete project > by letting a student code for it as part of the SoC or wouldnât this be > possible since a new project isnât yet active and viable? Yes, you can do. It will have to compete with other ideas for top ranking. > Who decides which ideas will be worked on and who decides which student > works on which? Each organisation (in practice, this means a group of people prepared to be mentors) reads and ranks student proposals. After a certain date, Google tell us how many projects they will fund, and the top N are given the money. > What are the obligations of a mentor? (a) To carefully read and vote on quite a lot of student proposals. (b) If chosen to mentor a funded project, to guide the student throughout the project time, primarily by email (and/or IRC). Also to write two reports on progress (mid-term and final), that directly determine whether the student gets paid. > Is it okay to create an idea, become the mentor for this idea > and propose a concrete student for it? Sure. But your idea and student will need to compete for ranking. > What do I have to do to become a mentor? Start by adding yourself to the wiki. > What are Haskell.org's criteria for selecting mentors? According to the > above-mentioned FAQ, Google wants to know these criteria as specifically as > possible. I'm not sure we have definite criteria. I guess that the community generally recognises your name as a contributor to the Haskell language, libraries, tools, or whatever. Regular and visible engagement with the community would count for a lot. > Finally, should the ideas be chosen so that they are solvable by a student > working full time on them during the three months of the SoC? Exactly so. This year, Google have set things up with a greater time period between notification of acceptance, and the official beginning of coding, so that students have more preparation time before full-time work starts. > The problem is that at many German universities lectures go until > July. At our university, for example, lecture time ends in mid of July > and is followed by two weeks for exams. So a faithful student would > only have the last month for working full time on the SoC. Google have indeed set up the timetable largely with US universities in mind. So yes, it is certainly a disadvantage to a German student that they cannot work full-time for the three months. Regards, Malcolm

1 0

open a browser from the command line, wait a few seconds, and shut it. (ie, translate forking from bash to haskell)
by Thomas Hartman 08 Mar '07

08 Mar '07

I have a bash script that opens a browser for a few seconds, and then closes it. Could someone point me up the equivelant(s) in haskell, h4sh, hsh, etc,0 and friends? I reckon this amounts to, what's the process for translating forking from bash to haskell. ******** #!/bin/bash konqueror http://www.google.com & pid=$! # give the page some time to load sleep 5 kill $pid ******** By the way, this isn't an academic question -- I'm using this simple script to verify various html downloads by checking the konqueror html cache for text strings I'm interested in, for pages that can't be easily downloaded with wget/web mechanize because of javascript and redirect nastiness. Also, for those interested in shell-equivelance strategies, I posted essentially the same question to perlmonks at http://perlmonks.org/?node_id=603868

2 1

Re: [Haskell-cafe] TVars & throw
by Thomas Conway 08 Mar '07

08 Mar '07

On 3/8/07, Chris Kuklewicz <haskell(a)list.mightyreason.com> wrote: > What happens in your throw/catch case if I have > stm1 = do some_stm_code_that_throws_your_exception > stm2 = return Foo > and I run "atomically (stm1 `orElse` stm2)" ? > Answer: The exception will prevent running stm2. In the *specific* case of the external dictionary code, there is no orElse case to worry about since the algorithms are deterministic in this sense. For a more general case, it is an interesting problem to consider. You might want something like throwIfNothingElseSeemsLikeAGoodIdea, so that you can attempt any alternatives, and if none succeed then throw (and I guess choose the first if more than one alternative wants to throw - I like determinism). > > Um, is > > unsafeIOToSTM $ atomically trans > > going to run you into problems? > > YES! My point is that onRetry really wants to be not "IO t" but "IO_execpt_STM t", but there's no way of ensuring that, which unfortunately antagonizes modularity in the same kind of way that locks do. It requires you to know how the implementation of the IO actions you use work, in case they use STM inside. Since the actions may come out of a library somewhere, you need to know how the library is implemented. <sigh> Why are tricky problems tricky? I thought Haskell was supposed to make everything easy. ;-) T. -- Dr Thomas Conway You are beautiful; but learn to work, drtomc(a)gmail.com for you cannot eat your beauty. -- Congo proverb

1 0

EnumSet and EnumMap
by Chris Kuklewicz 08 Mar '07

08 Mar '07

I could not quickly find anyone else writing this boiler plate, so I have posted this useful wrapper on the Haskell wiki at http://haskell.org/haskellwiki/EnumSet_EnumMap This uses a cheap newtype to wrap IntSet and IntMap so that you can store any Enum in them. It saves either writing many toEnum/fromEnum functions or using the slower and more generic Data.Set and Data.Map. The original motivation was to go from Map Char to IntMap. And as a bonus, the type signature of the newtype is the same kind as Data.Set and Data.Map (which matters when declaring instances...) > newtype EnumSet e = EnumSet {unEnumSet :: S.IntSet} > deriving (Monoid,Eq,Read,Show,Ord) > newtype EnumMap k a = EnumMap {unEnumMap :: M.IntMap a} > deriving (Eq,Read,Show,Ord,Monoid,Foldable,Functor) This has been quickly tested with GHC 6.6 and may contain typographical errors I have not caught yet. -- Chris

2 1

Re: [Haskell-cafe] Usage of . and $
by David House 08 Mar '07

08 Mar '07

On 07/03/07, Thomas Conway <drtomc(a)gmail.com> wrote: > Of course, what really gets me, is when I start trying to use $ in > type signatures and declarations: > ... Map ByteString $ foo (bar baz) qux .... It's almost possible! GHC gives us infix type synonyms: type a $ b = a b (Probably needs -fglasgow-exts.) Sadly we don't have a fixity system for type operators :( -- -David House, dmhouse(a)gmail.com

2 2