Re: [Haskell-cafe] Anyone up for Google SoC 2010?

I'd also be happy to mentor. Where is the official place to collect project ideas? We used trac previously, are we still using it or are we now on Reddit? Thanks, Neil 2010/2/1 sterl s.clo...@gmail.com: Malcolm Wallace wrote: Google has announced that the Summer of Code programme will be

[Haskell-cafe] Hackage Package version ranges

Hi, I maintain the Haskell package HLint. HLint depends on haskell-src-exts, cpphs, hscolour and uniplate, plus things which are shipped with GHC. For each of the external library dependencies, I have to specify a version constraint. For example, I developed HLint against cpphs-1.10 so I can

Re: [Haskell-cafe]SYB/Generics documentation inaccessible

I emailed Simon Peyton Jones about this a few weeks ago (he links to these pages) and got the reply thanks, will chase - so people are aware of it. The links are in many places, which is a bit of a shame. Thanks, Neil On Tue, Feb 2, 2010 at 8:51 PM, Arne Dehli Halvorsen arne@gmail.com wrote:

Re: [Haskell-cafe] Hackage Package version ranges

Alternatively, if I could sign up to be emailed when something went wrong, I'd happily fix it. i.e. I'd like an email either when my package fails to compile against the latest version of all packages but within my constrained range, or when the latest version falls outside my constraint

Re: [Haskell-cafe] Trapping getChar before echo

Hi Mark, http://haskell.org/hoogle/?hoogle=set+echo Thanks, Neil On Sun, Jan 31, 2010 at 8:47 AM, Mark Spezzano mark.spezz...@chariot.net.au wrote: Hi, Is there any way of trapping keystrokes in Haskell, modifying them, and then echoing? Basically I want to give the user a prompt  like:

[Haskell-cafe] Community.haskell.org is down

http://downforeveryoneorjustme.com/community.haskell.org/ Thanks, Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] problems installing cabal on windows

Hi, Try a: cabal update cabal install cabal-install That will set you up with a newer version of Cabal, that should be GHC 6.12 compatible. Make sure you do all this while GHC 6.10 is on the path, so it knows how to install cabal-install. Thanks, Neil On Fri, Jan 29, 2010 at 6:36 PM, Han

Re: [Haskell-cafe] Supporting GHC 6.10 and 6.12 in HDBC-postgresql Setup.hs

The other HDBC problem I have is various dependencies relying on QC1. The next HP will ship with QC 2.1 (in coming weeks), so it might be a good time for people to start migrating, since that will be the only version of QC on many distros. I would strongly suggest moving to QC 2 for other

Re: [Haskell-cafe] Re: could we get a Data instance for Data.Text.Text?

Hi The problem with Data for Text isn't that we have to write a new instance, but that you could argue that proper handling of Text with Data would not be using a type class, but have special knowledge baked in to Data. That's far worse than the Serialise problem mentioned above, and no one

[Haskell-cafe] Re: Failing to install hxt: tagsoup versioning

Hi Minor version bumps which leave the API unchanged shouldn't break anything, small additions to the API should rarely break things, so if people adhere to http://www.haskell.org/haskellwiki/Package_versioning_policy , Neil, in this case i think, tagsoup's version shouldn't have changed

Re: [Haskell-cafe] Re: could we get a Data instance for Data.Text.Text?

Hi, The problem with Data for Text isn't that we have to write a new instance, but that you could argue that proper handling of Text with Data would not be using a type class, but have special knowledge baked in to Data. That's far worse than the Serialise problem mentioned above, and no one

Re: [Haskell-cafe] Re: could we get a Data instance for Data.Text.Text?

Would it be possible to get a Data instance for Data.Text.Text? From the last time this came up, I gather that the correctish thing to do (for reasons too obscure to me) is to teach SYB and its many cousins about Text, or else there'll be some sort of disturbance in the Force. No, that's

Re: [Haskell-cafe] http://trac.haskell.org down?

Hi community.haskell.org is down as well :-( Thanks, Neil On Fri, Jan 22, 2010 at 8:41 PM, James Britt ja...@neurogami.com wrote: Been trying to reach http://trac.haskell.org for most of the morning, but nothing comes up. Seems I'm not alone:

Re: Re[4]: [Haskell-cafe] Poor man's generic programming

Hi Bulat, The intention was always that the manual should be an up-to-date version that contains everything people need to use the library, but not the internal details. The paper was revised in to my thesis chapter, which is probably the best description of the internals of Uniplate. The thesis

Re: [Haskell-cafe] Poor man's generic programming

Hi Henning, Uniplate is simple (only multi parameter type classes, and even then only in a very simple usage), fast (one of the fastest generics libraries) and concise (probably the most concise generics library). It's also not as powerful as most of the other generics libraries, but I find

Re: Re[2]: [Haskell-cafe] Poor man's generic programming

Hi Bulat, Uniplate might be the answer you are looking for - http://community.haskell.org/~ndm/uniplate it's brilliant! some people has the talent to discover complex things and you have the talent to make complex things simple. it's first and only generics library that i can easily learn

Re: [Haskell-cafe] Poor man's generic programming

Hi Henning, Uniplate might be the answer you are looking for - http://community.haskell.org/~ndm/uniplate Uniplate is simple (only multi parameter type classes, and even then only in a very simple usage), fast (one of the fastest generics libraries) and concise (probably the most concise

Re: [Haskell-cafe] Typed Configuration Files

Hi The CmdArgs manual might help: http://community.haskell.org/~ndm/darcs/cmdargs/cmdargs.htm Seriously, cmdargs is *brilliant*.  It's also magic (to me). On this list, I'm uncertain whether brilliant is a warning or a recommendation, but magic is clearly irresistible, so I had a go at

[Haskell-cafe] Hackage down

Hi Hackage is down: http://downforeveryoneorjustme.com/hackage.haskell.org Thanks, Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] Typed Configuration Files

Hi, Seriously, cmdargs is *brilliant*.  It's also magic (to me). Not only to you in fact it is black magic since it uses unsafePerformIO :( The problem isn't that it's black magic or that it uses unsafePerformIO - the problem is that it's horribly impure, so doesn't obey referential

Re: [Haskell-cafe] Significant slow-down in parallel code?

4, 2010 at 3:14 PM, Neil Mitchell ndmitch...@gmail.com wrote: Hi Jamie, First question, what version of GHC are you using? There are significant performance improvements to parallel code in GHC 6.12, so it's worth an upgrade. Once you've upgraded you might want to try out threadscope which

Re: Where did the GHC API go?

Hi, As a suggestion to stop this issue repeating, why not have the latest URL be an automatic and visible forward to the stable and guaranteed URL? (I can't remember the HTTP code, but I think it's permanent redirect) That way people are less likely to see these unstable URL's in their web

Re: [Haskell-cafe] Significant slow-down in parallel code?

Hi Jamie, First question, what version of GHC are you using? There are significant performance improvements to parallel code in GHC 6.12, so it's worth an upgrade. Once you've upgraded you might want to try out threadscope which is designed to help track down these sorts of problems. If you are

Re: Where did the GHC API go?

I've now updated Hoogle to point at the new links. I still think the old link's should be restored (perhaps as a permanent redirect code?), but at least it doesn't break Hoogle now. Thanks, Neil On Mon, Dec 28, 2009 at 11:06 AM, Malcolm Wallace malcolm.wall...@cs.york.ac.uk wrote: Too late. We

Re: Where did the GHC API go?

Hi Ian, Yes, this is now http://haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/Prelude.html#v:filter                                                   I'd suggest that Hoogle shold probably use its own copy of the docs, so that it stays in sync with them. Also, you

Re: Where did the GHC API go?

Note that other links have gone broken recently: http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#v:filter These links are relied upon by Hoogle and Google. I suspect they have the same cause. Thanks, Neil On Mon, Dec 21, 2009 at 12:38 PM, Simon Marlow marlo...@gmail.com

Re: [Haskell-cafe] Instances of `IsString`.

Hi Jason, I believe the original purpose of IsString was to enable writing of DSL's, much like described in this paper: http://portal.acm.org/citation.cfm?id=1411236 As such, you might find far more uses of IsString inside DSL's, some of which are likely to remain private. It was never designed

Re: [Haskell-cafe] SmallCheck design question

Hi, I'm cc'ing the people behind smallcheck, who can give definitive answers. 1. why are the tuple constructors treated differently? I'd expect depth (x,y) = succ $ max (depth x) (depth y) but the succ is missing. I think this was a design choice. Some people would consider: data Foo = Foo

Re: [Haskell-cafe] Hayoo and Hoogle (beginner question)

Hi, It probably helps to know some of the history, as it explains a lot of what you see today. Hoogle was written first (about 5 years ago now), before there was hackage (so it doesn't search hackage), and with an emphasis on type search (as that's cool). Hayoo came a lot later (about 2 years ago

Re: [Haskell-cafe] Hoogle Down

Hi Elliot, It is the right place, and Hoogle is now back up. Unfortunately the server it was run was out of disk space, which caused Hoogle to fail. Hopefully it won't happen again. Thanks, Neil 2009/11/29 Elliot Wolk elliot.w...@gmail.com: hello! im not sure that this is the correct mailing

Re: [Haskell-cafe] hoogle down

Hi Keith, Thanks for pointing this out. I've no idea why it's failing, but will check once I get home - unfortunately the machine I'm currently on doesn't permit me to ssh in and find out. Thanks, Neil On Sat, Nov 28, 2009 at 6:53 AM, Keith Sheppard keiths...@gmail.com wrote: hoogle is down

Re: [Haskell-cafe] hoogle down

? 2009/11/28 Neil Mitchell ndmitch...@gmail.com Hi Keith, Thanks for pointing this out. I've no idea why it's failing, but will check once I get home - unfortunately the machine I'm currently on doesn't permit me to ssh in and find out. Thanks, Neil On Sat, Nov 28, 2009 at 6:53 AM, Keith

Re: [Haskell-cafe] Some useful TH templates

Hi Yair, I wrote some Template Haskell templates that I think may be of use to others. The first generates in and with functions for newtypes. This looks very nice. Have you thought about putting this code in to the Derive package? (http://community.haskell.org/~ndm/derive, and also on

[Haskell-cafe] community.haskell.org is down

Hi, community.haskell.org isn't responding, I get connection failures. Thanks, Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Re: [Haskell-cafe] haskell-src-exts Question

Hi Adding brackets that MUST have been there, by default, sounds like a great idea. The alternative is getting it wrong, so I think that's very safe. Adding brackets that MIGHT have been there is a lot less clear cut. One important consideration is that the fixities you parse/pretty-print with

Re: [Haskell-cafe] haskell-src-exts Question

Hi Daniel, Funny, I did the opposite approach the other day (not saying either is better :)); that is: parenthesize everything while building the AST (with a wrapper for App) and then: I have utilities in HLint for that too - but I don't want to remove users brackets automatically :-) Btw,

Re: [Haskell-cafe] Opinion about JHC

Hi John, Do you use jhc when you develop jhc?  I.e., does it compile itself. For me, this is the litmus test of when a compiler has become usable. I mean, if even the developers of a compiler don't use it themselves, why should anyone else? :) Well, this touches on another issue, and that

Re: [Haskell-cafe] haskell-src-exts Question

Hi Niklas, Do I have to write my own prettyprinter? Do I have to put in explicit parentheses? The latter seems unsatisfactory as my generated AST is unambiguous and bracketing ought to be part of the prettyprinter. The former would be quite a lot of code as there are many cases to

Re: [Haskell-cafe] faster compiling for ghc

Hi, I'd really love a faster GHC! I spend hours every day waiting for GHC, so any improvements would be most welcome. I remember when developing Yhc on a really low powered computer, it had around 200 modules and loaded from scratch (with all the Prelude etc) in about 3 seconds on Hugs. ghc

Re: [Haskell-cafe] The weirdest error I've ever seen...

Hi Joe, Serious question now, There's a fair amount of definitely irrelevant code (like the definition of the `Email` type, etc), should I post that in the report too (assuming it doesn't work in 6.12 or I can't get 6.12 working to try it)? http://hackage.haskell.org/trac/ghc/wiki/ReportABug

Re: [Haskell-cafe] Hoogle is great but ...

Following up on this rather old thread, if you want to see a module which has lots of input/output example pairs, and properties, in the documentation then look at filepath (hoogle for takeExtension as an example). These properties are also automatically transformed in to test cases, so filepath

Re: [Haskell-cafe] hSeek in Windows

Hi Philippos, The secret is there in the error message: seek operations on text-moddles are not allowed on this platform You need to set your file in to binary mode, with hSetBinaryMode (http://haskell.org/hoogle/?hoogle=hSetBinaryMode) or openBinaryFile

Re: [Haskell-cafe] hackage is down.

For future reference, if Hackage or community is down where should that be reported to? On Sun, Nov 1, 2009 at 7:01 PM, Don Stewart d...@galois.com wrote: This has been reported to the sysadmins. tphyahoo: http://hackage.haskell.org ___

[Haskell-cafe] Re: Suggested additions to System.FilePath.Posix/Windows

Hi Marcus, Thanks for your suggestions. I'm a Windows user so aren't really qualified to comment on these suggestions - it depends what Posix users would like. I suggest you follow the Library Submission Process - filepath is now a core library, and as such I don't have the freedom/power to

[Haskell] ANN: CmdArgs - easy command line argument processing

Hi, I am pleased to announce CmdArgs v0.1. CmdArgs is a library for easy command line argument processing - taking the arguments passed into your program from getArgs and converting them into a structured value for use in your program. Compared to the System.Console.GetOpts library there are two

[Haskell-cafe] Community.haskell.org is down

Hi, http://community.haskell.org/ seems to be down for me. In general, who should this be reported to? Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell] ANN: HLint 1.6.8

Hi, I am pleased to announce HLint 1.6.8. HLint is a tool for suggesting improvements to your source code. It suggests the use of library functions you may have been unaware of, finds patterns of recursion that are really folds/maps, hints about extensions you aren't using and much more. HLint is

Re: [Haskell-cafe] Error during hlint install ?

Hi Dusan,  Am I doing something wrong if I get the following error during cabal installation of hlint? Is there any way how to solve it? The problem is that version 1.15 of hscolour released recently is incompatible with 1.13 which HLint was being tested against. I've now switched over to

Re: [Haskell-cafe] Unifcation and matching in Abelian groups

Hi, I ran your code thought HLint (http://community.haskell.org/~ndm/hlint), and it suggested a couple of things (mainly eta reduce). The most interesting suggestions are on your main function: main :: IO () main = do done - isEOF case done of True - return ()

Re: [Haskell-cafe] Unifcation and matching in Abelian groups

Hi I've given up on using if-then-else in do expressions.  They confuse emacs.  There is a proposal for Haskell' to fix the problem, but until then, I will not use them in do expressions. It's a shame, there are ways of indenting them that work, but they're not as natural. It's a wart, but it

Re: [Haskell-cafe] Request for comments - hdnsomatic

de Guadalajara 2009/8/16 Neil Mitchell ndmitch...@gmail.com Hi An easy way to get some instant feedback is to run HLint on it: http://community.haskell.org/~ndm/hlint The results are: C:\Neil\hlinthlint Example.hs Example.hs:42:1: Warning: Use liftM Found:  readFile p = return

Re: [Haskell-cafe] Re: Changelogs and available since

Hi I would use hoogle for this. Currently it stores the package name and the symbols of the modules about a package. What do you think about hayoo?  I prefer this to hoogle, as hayoo has more complete database across hackage packages, AFAIK Hayoo gets it package database out of haddock with

Re: [Haskell-cafe] Request for comments - hdnsomatic

Hi An easy way to get some instant feedback is to run HLint on it: http://community.haskell.org/~ndm/hlint The results are: C:\Neil\hlinthlint Example.hs Example.hs:42:1: Warning: Use liftM Found: readFile p = return . lines = return . map (second tail . break (== '=') . filter (/= ' '))

Re: [Haskell-cafe] Using -Nx Option with GHC

Hi Mark, I compile with ghc --make -O2 -threaded That should work - try deleting all .o/.obj files and the executable and trying to compile again. Thanks Neil ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org

Re: [Haskell-cafe] Request for Changelogs

Hi I’m involved in packaging Haskell stuff for Debian. Now, the Debian tools we have for that tell me „Hlint has a new version, 1.6.5, which is newer than the one you packages, 1.6.4. Huh, nice. What has changed? Is it relevant for Debian? Is it worth a new upload? There is no easy way to

Re: [Haskell-cafe] Request for Changelogs

Hi http://community.haskell.org/~ndm/darcs/hlint/CHANGES.txt That will now be updated for future HLint releases. Thanks, Neil On Thu, Aug 6, 2009 at 3:49 PM, Joachim Breitnerm...@joachim-breitner.de wrote: Hi, Am Donnerstag, den 06.08.2009, 15:39 +0100 schrieb Neil Mitchell: So please

Re: [Haskell-cafe] Hugs faster and more reliable than GHC for large list monad 'do' block

Hi I think the issue you're running in to with 6.4 is this one: http://hackage.haskell.org/trac/ghc/ticket/830 - known and fixed a while back. Thanks Neil On Thu, Aug 6, 2009 at 9:59 PM, Dan Westonweston...@imageworks.com wrote: I assume for the return line, you meant to return a list, not a

Re: [Haskell-cafe] Typeclass for functions taking different kinds of strings

Hi is there currently a library that makes unifying them easy? I currently use this library: http://community.haskell.org/~ndm/darcs/tagsoup/Text/StringLike.hs Not yet released, and rather specific to what I was wanting to do, but does work for me. I'm happy for people to steal bits from that

Re: [Haskell-cafe] Typeclass for functions taking different kinds of strings

Hi It looks nice but is not really a solution for passing large amounts of data efficiently. Converting everything to String creates too much overhead for large chunks of data. There is uncons, which never creates big strings. But yes, adding more bulk operations (i.e. lookup) might be

Re: [Haskell-cafe] Haskell interface files: Why used? What about same data in object files?

Hi Some good reasons for having a separate interface are:  they can be human-readable and human-writable (ghc's do not fulfill this criterion); they can be used to bootstrap mutually recursive modules in the absence of any object files (ghc uses .hs-boot files instead); other tools can

Re: Proposals and owners

Hi   remove FixityResolution from the context-free grammar http://hackage.haskell.org/trac/haskell-prime/wiki/FixityResolution Please take a look and comment.  This fixes a nasty bug in the Haskell syntax - albeit one that doesn't cause problems in practice, but still.  I think the changes

Re: [Haskell-cafe] Need feedback on my Haskell code

Hi Kashyap, My first suggestion would be to run HLint over the code (http://community.haskell.org/~ndm/hlint) - that will spot a few easy simplifications. Thanks Neil On Tue, Jul 28, 2009 at 2:04 PM, CK Kashyapck_kash...@yahoo.com wrote: Hi Everyone, I managed to write up the line drawing

Re: StricterLabelledFieldSyntax

Hi Would it be proper to create a counterproposal for this syntax? ReversedLabelledFieldSyntax? I would claim that, of the existing Haskell code, StricterLabelledFieldSyntax only rejects unclear (bad) code, and requiring it be changed (to be made clearer) is a good thing. I haven't seen

Re: StricterLabelledFieldSyntax

I haven't seen anyone else claim to use the current more liberal syntax for fields, but I know that I do rather extensively. I would consider: Just A {a = 1} To be confusing, but if you simply omit the space: Just A{a = 1} I now find that perfectly clear and unambiguous. I did

Re: [Haskell-cafe] Implicit concatenation in list comprehensions

Except that it's ugly compared to the proposed extension. With the extension you can put things in the same, right place: renderGhcOptions opts =     ghcOptExtraPre opts  -- source search path  ++ [ -i      | not (null (ghcOptSearchPath opts)) ]  ++ [ -i, dir | dir - ghcOptSearchPath opts

Re: [Haskell-cafe] Implicit concatenation in list comprehensions

Hi Max, For fun, I spent a few hours yesterday implement support for this syntax in GHC, originally propsed by Koen Claessen: [k, =, v, | (k, v) - [(foo, 1), (bar, 2)] [foo, =, 1, , bar, =, 2, ] This is a generalisation of list comprehensions that allows several items to be

[Haskell] ANN: HLint 1.6

Hi, I am pleased to announce HLint 1.6, a tool for automatically suggesting improvements to your Haskell code. For example: $ hlint darcs-2.1.2 CommandLine.lhs:49:1: Warning, eta reduce Found:quotedArg ftable = between (char '') (char '') $ quoteContent ftable Why not: quotedArg = between

Re: group keyword with TransformListComp

on this instead. As Simon says, suggestions are welcome! Note that group *should* be parsed as a special id, so you can still import D.L qualified and then use dot notation to access the function. Cheers, Max 2009/6/21 Neil Mitchell ndmitch...@gmail.com: Hi, The TransformListComp

Re: [Haskell-cafe] Parsing .dot files?

Hi I have some code, but never got round to uploading it or turning it in to a package. If the graphviz package doesn't have what you want I'm happy to give you a copy. (I would attach the code but I don't have it on this machine) Thanks Neil On Wed, Jun 24, 2009 at 7:38 AM, minh

group keyword with TransformListComp

Hi, The TransformListComp extension makes group a keyword. Unfortunately group is a useful function, and is even in Data.List. Thus, Data.List.group and TransformListComp are incompatible. This seems a very painful concession to give up a nice function name for a new extension. Is this

Re: --out-implib when linking shared libraries

library then it might be good idea not to build the import libraries at all. Regards,  Krasimir On Sat, May 16, 2009 at 1:26 PM, Duncan Coutts duncan.cou...@worc.ox.ac.uk wrote: On Sat, 2009-05-16 at 11:07 +0100, Neil Mitchell wrote: I don't, although having that option wouldn't be a bad thing

Re: [Haskell-cafe] HXT XmlPicklers - TH Derivation

Hi Max, I have developed some simple TH code to automatically derive XmlPickler instances for my types and if there is interest, I will clean it up and submit a patch.  Its not complete, but is a start.  Any interest? Why not submit it to derive: http://community.haskell.org/~ndm/derive

Re: [Haskell-cafe] GSoC update: sneak peek at the live heap profiler

Hi Gergely, I haven't seen this blog on planet.haskell.org, but it definitely should be! Instructions on how to have it added are on that page. Thanks, Neil 2009/6/3 Patai Gergely patai_gerg...@fastmail.fm: Hello everyone, finally there's a bit of eye candy for anyone interested in the heap

Re: mtl and network packages in GHC 6.10.3.*

release seems like it was a massive mistake, shouldn't these packages be reinstated at least until GHC 6.12? Thanks Neil On Wed, May 27, 2009 at 8:57 AM, Johan Tibell johan.tib...@gmail.com wrote: On May 27, 2009 3:33 AM, Neil Mitchell ndmitch...@gmail.com wrote: Hi, I just downloaded the Windows

mtl and network packages in GHC 6.10.3.*

Hi, I just downloaded the Windows snapshot of 6.10.3.20090526, and found that mtl and network don't seem to be included. $ ghc-pkg list c:/ghc/ghc-6.10.3.20090526\package.conf: Cabal-1.6.0.1, Cabal-1.6.0.3, Win32-2.2.0.0, array-0.2.0.0, base-3.0.3.1, base-4.1.0.0, bytestring-0.9.1.4,

Re: [Haskell-cafe] Anglohaskell?

Sounds fun! I have no time to organise it, but someone should. It really isn't that hard! Thanks Neil On Mon, May 25, 2009 at 4:47 PM, Philippa Cowderoy fli...@flippac.org wrote: Is anyone up for Anglohaskell this year? Perhaps more importantly, is anyone willing to step forward to run it? I

[Haskell-cafe] Re: ANN: New repository and trac for haskell-src-exts

Hi Niklas, Do you want people to cc bugs they want to vote for - like the GHC people do? Thanks Neil On Tue, May 26, 2009 at 12:56 AM, Niklas Broberg niklas.brob...@gmail.com wrote: Hi all, In preparation for my GSoC project, I've set up some new infrastructure for the haskell-src-exts

Re: Should exhaustiveness testing be on by default?

  Do you really want exhaustiveness, or is what you actually want safety? I want both.  Exhaustiveness checking now and forever, because it's a modular property.  Safety when somebody gets around to implementing whole-program analysis in the compiler I use, when I feel like waiting around

Re: Should exhaustiveness testing be on by default?

Catch already does assertion checking (1). Its runtime on moderate to small programs (HsColour in particular) is far less than the time GHC takes to compile them, and I still have no idea what its runtime is on enormous programs (2). An analysis can be whole program and can be slow, one does

Re: Should exhaustiveness testing be on by default?

If Catch says your program will not crash, then it will not crash. I even gave an argument for correctness in the final appendix of my thesis http://community.haskell.org/~ndm/thesis/ (pages 175-207). Of course, there are engineering concerns (perhaps your Haskell compiler will mis-translate

Re: Should exhaustiveness testing be on by default?

OK. i'm just trying to get an intuition for the analysis. Catch is defined by a small Haskell program. You can write a small Haskell evaluation for a Core language. The idea is to write the QuickCheck style property, then proceed using Haskell style proof steps. The checker is recursive - it

Re: Should exhaustiveness testing be on by default?

  ... exhaustive pattern checking might well help out a lot of   people coming from untyped backgrounds... Or even people from typed backgrounds.  I worship at the altar of exhaustiveness checking. Do you really want exhaustiveness, or is what you actually want safety? With

Re: Should exhaustiveness testing be on by default?

Core file representing a whole program, including all necessary libraries, then implementing Catch would be a weekends work. Thanks Neil On Tue, May 19, 2009 at 12:01 PM, Neil Mitchell ndmitch...@gmail.com wrote:   ... exhaustive pattern checking might well help out a lot of   people coming from

Re: Should exhaustiveness testing be on by default?

I'm not a particular fan of exhaustiveness checking. It just encourages people to write: foo (Just 1) [x:xs] = important case foo _ _ = error doh! So now when the program crashes, instead of getting a precise and guaranteed correct error message, I get doh! - not particularly helpful for

Re: strictness of interpreted haskell implementations

Hi       data S = S { a :: Int, b :: ! Int }       Main a (S { a = 0, b = 1 })       0       Main a (S { a = 0, b = undefined })       0 Ho hum.  Is this a known difference? I've submitted a bug: http://hackage.haskell.org/trac/hugs/ticket/92 As an ex teaching assistant my

[Haskell-cafe] community.haskell.org and code.haskell.org problems

Hi, I regularly (almost daily) have problems reaching both community and code.haskell.org, getting 500 server error messages. I've decided to make all my Haskell code available on community, which means that when it goes down, I can't access my repos - which is not great. Is there a reason for

[Haskell-cafe] community.haskell.org and code.haskell.org problems

Hi, I regularly (almost daily) have problems reaching both community and code.haskell.org, getting 500 server error messages. I've decided to make all my Haskell code available on community, which means that when it goes down, I can't access my repos - which is not great. Is there a reason for

Re: --out-implib when linking shared libraries

I've just built a Haskell dll on Windows. As part of the process it generated an 14Mb foo.dll, and a 40Mb foo.dll.a. Looking at the flags passed to ld I see --out-implib=foo.dll.a. What is the purpose of the .a file? What might it be needed for? Is it possible to suppress it? It looks like

--out-implib when linking shared libraries

Hi, I've just built a Haskell dll on Windows. As part of the process it generated an 14Mb foo.dll, and a 40Mb foo.dll.a. Looking at the flags passed to ld I see --out-implib=foo.dll.a. What is the purpose of the .a file? What might it be needed for? Is it possible to suppress it? I could easily

Re: [Haskell-cafe] haskellnet

Hi Email the original author, if you can. Ideally work with them to upload a working version to hackage. If they're not interested hopefully they'll make you the new maintainer. If you can't contact them, just upload a new version anyway - as long as it's done for the benefit of the community and

Re: [Haskell-cafe] Hoogle: converting binary .hoo into text?

Hi Sure. We're building with a graphical representation of a Haskellish language (a tiny subset of Haskell actually). The target audience is graphical artists and designers. For testing, I would like to populate the library with primitives taken from the Haskell base libraries.  I tried

Re: [Haskell-cafe] Generating Haskell with associated types (and kind annotations)

Hi I guess I should write the skeleton of the code I want to generate, get HSE to parse it, and then replace the parts I want to change of the AST with what I need? Is there a nicer way (TH-like?) to get the modified AST into GHC than prettyprinting the AST again and asking GHC to compile

Re: Can HLint help spot space leaks? (was: Re: [Haskell-cafe] Generating Haskell with associated types (and kind annotations))

Hi Jason, Hi Neil, A bit off-topic, but your post reminded me:  Does HLint currently help the user find space leaks?  For example, does it recommend strict folds instead of lazy folds?  I looked at the FAQ but this was not listed.  I don't really know how feasible this is. It spots when you

Re: [Haskell-cafe] Generating Haskell with associated types (and kind annotations)

Hi Dan, I was wondering whether anyone had any suggestions on a good way to generate repetitive code with associated types and kind annotations. haskell-src-exts is the answer: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell-src-exts From the project description:

Re: [Haskell-cafe] Why is Bool no instance of Num and Bits?

that. Is that a GHC thing? Is it strictly necessary? Seems like it could be done in the Num instance for Integers, Ints, etc. On Fri, May 8, 2009 at 11:51 AM, Neil Mitchell ndmitch...@gmail.com wrote: Err, I'm not seeing the danger of this (+) :: forall a. (Num a) = a - a - a Doesn't

Re: [Haskell-cafe] Why is Bool no instance of Num and Bits?

Err, I'm not seeing the danger of this (+) :: forall a. (Num a) = a - a - a Doesn't this require the two parameters to be the same instance of Num? I didn't at first, then I remembered: 1 + True = fromInteger 1 + True And if we have Num for Bool, it type checks. Thanks Neil

Re: [Haskell-cafe] Why is Bool no instance of Num and Bits?

Does that also mean that you could write: if 3 - 4 then ... else ...  (= if (fromInteger 3 :: Bool) - (fromInteger 4 :: Bool) then ... else ...) No. 3 - 4 is an Integer, the proposal is to convert Bools to Ints, not Ints to Bools. Of course, Lennart has been asking for precisely this

Re: runhaskell a parallel program

Hi If however I run it with runhaskell Test.hs +RTS -N2 I get told the -N2 flag isn't supported. Is there a way to runhaskell a program on multiple cores? Is this a bug that it doesn't work, a feature request I'm making, or is there some trick to getting it working I haven't thought of? I'll

Re: Re[2]: runhaskell a parallel program

Hi Bulat, Neil, you can implement it by yourself - convert -j3 in cmdline to +RTS -N3 -RTS and run program itself. alternatively, you can use defaultsHook() although i'm not sure that it can change number of Capabilities Can I run a program itself? getProgName doesn't give me enough to

Re: runhaskell a parallel program

Hi Isn't ghc -e using the byte-code interpreter? Yes; apparently it works, though we still haven't stress-tested it running real parallel programs using GHCi with +RTS -N2. It seemed perfectly stable when I tried, on a few examples I had knocking around. Still, parallelism is about

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