[Haskell-cafe] BayHac '13

Please join us for a weekend of Haskell hacking: *BayHac '13* *May 17th ~ 19th, 2013* *Hacker Dojo* *Mountain View, CA* Full details on the Haskell Wiki: BayHac '13 - Mark ___ Haskell-Cafe mailing list Ha

[Haskell-cafe] Lazy object deserialization

Hey all, All the object serialization/deserialization libraries I could find (pretty much just binary and cereal) seem to be strict with respect to the actual data being serialized. In particular, if I've serialized a large [Int] to a file, and I want to get the first element, it seems I have

[Haskell-cafe] ANN: retry 0.1 - retry combinators for monadic actions that often fail

Dear Cafe, I'm happy to announce the availability of the retry package on Hackage[1] and Github[2]. The package provides a few useful combinators for monadic actions that often fail and should be retried in cases of a certain set of exceptions (or failure modes). Such cases are quite common wh

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

[1]: http://github.com/alpmestan/hnn On Wed, Mar 13, 2013 at 1:03 AM, Alp Mestanogullari wrote: > Hi, > > My suggestion may sound a bit odd, but if they're looking for a > challenging but still simple enough project, I'd love for people to test > out the new version of hnn (not yet released, but

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

Hi, My suggestion may sound a bit odd, but if they're looking for a challenging but still simple enough project, I'd love for people to test out the new version of hnn (not yet released, but on github [1]) and make something fun with it. I'd love to mentor this and add things to the library altoge

Re: [Haskell-cafe] cabal install oddities

On Tue, Mar 12, 2013 at 3:10 PM, Tycho Andersen wrote: > On Tue, Mar 12, 2013 at 03:28:08PM -0400, Brandon Allbery wrote: >> >> "cabal install" unpacks a package into /tmp in order to build it. My guess >> is your OS has /tmp mounted noexec. I don't know offhand how you override >> this in cabal.

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

Hi, Am Montag, den 11.03.2013, 11:48 -0400 schrieb Brent Yorgey: > If you have any such projects, I'd love to hear about it! Just send > me a paragraph or so describing your project and explaining what > task(s) you could use help with --- something that I could put on the > course website for st

Re: [Haskell-cafe] Overloading

> > On Tue, Mar 12, 2013 at 5:54 PM, Richard A. O'Keefe > wrote: > > Carlos Camarao wrote: > > >> Sorry, I think my sentence: > >>"To define (+) as an overloaded operator in Haskell, > >> you have to define and use a type class." > >>is not quite correct. I meant that

Re: [Haskell-cafe] Overloading

On Mar 13, 2013, at 12:54 AM, "Richard A. O'Keefe" wrote: > The interesting challenge here is that we should have > >Date + Period -> Date Date - Period -> Date >Period + Date -> Date Period - Date -> ILLEGAL >Period + Period -> DeriodPeriod - Period -> Period >

Re: [Haskell-cafe] Overloading

If you add NoImplicitPrelude, I think you should also be able to do: import Prelude hiding (Num) import qualified Prelude (Num) instance Num a => Plus a a where type PlusResult a a = a a + b = a Prelude.+ b On Tue, Mar 12, 2013 at 2:24 PM, MigMit wrote: > On Mar 13, 2013, at 12:54 A

Re: [Haskell-cafe] Overloading

On Mar 13, 2013, at 12:54 AM, "Richard A. O'Keefe" wrote: > The interesting challenge here is that we should have > >Date + Period -> Date Date - Period -> Date >Period + Date -> Date Period - Date -> ILLEGAL >Period + Period -> DeriodPeriod - Period -> Period >

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

[4] http://hub.darcs.net/simon/rss2irc/browse/NOTES.org On 3/12/13 2:13 PM, Simon Michael wrote: Hi Brent, hledger is an existing project whose purpose, code and installation process is relatively simple. I'm happy to do a bit of mentoring. If this sounds suitable, I can suggest some easy fixes

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

Hi Brent, hledger is an existing project whose purpose, code and installation process is relatively simple. I'm happy to do a bit of mentoring. If this sounds suitable, I can suggest some easy fixes or enhancements, eg: ...hmm. In fact nothing on my long wishlist[1][2] looks all that quick.

Re: [Haskell-cafe] newtype a Constraint?

On 12 March 2013 13:18, Roman Cheplyaka wrote: > Is there a way to newtype a constraint? > > Imagine a type class parameterised over constraints. What do I do if I > want multiple instances for (essentially) the same constraint? It would make sense to add support for this to newtype directly. I t

Re: [Haskell-cafe] Overloading

Carlos Camarao wrote: > Sorry, I think my sentence: >"To define (+) as an overloaded operator in Haskell, > you have to define and use a type class." >is not quite correct. I meant that to define any operator in Haskell you have >to > have a type class defined with that operator as m

Re: [Haskell-cafe] monadic DSL for compile-time parser generator, not possible?

Mostly, because I want to do other sorts of compile-time inspections on the parser. Being able to generate the parser is just the easiest part to get started with. - jeremy On Tue, Mar 12, 2013 at 3:36 PM, dag.odenh...@gmail.com wrote: > Why not the parsers package [1]? Write the parser against

Re: [Haskell-cafe] monadic DSL for compile-time parser generator, not possible?

On Tue, Mar 12, 2013 at 3:32 PM, Jacques Carette wrote: > On 13-03-12 04:06 PM, Jeremy Shaw wrote: >>> data ParserSpec a where >>> AnyChar :: ParserSpec Char >>> Return :: a -> ParserSpec a >>> Join:: ParserSpec (ParserSpec a) -> ParserSpec a >>> FMap:: (a -> b) -> Pa

Re: [Haskell-cafe] monadic DSL for compile-time parser generator, not possible?

Why not the parsers package [1]? Write the parser against the Parsing class and then use trifecta or write instances for attoparsec or parsec. With enough inlining perhaps the overhead of the class gets optimized away? [1] http://hackage.haskell.org/package/parsers On Tue, Mar 12, 2013 at 9:06 P

Re: [Haskell-cafe] monadic DSL for compile-time parser generator, not possible?

On 13-03-12 04:06 PM, Jeremy Shaw wrote: It would be pretty damn cool if you could create a data type for generically describing a monadic parser, and then use template haskell to generate a concrete parser from that data type. [...] I would like to suggest that while it would be cool, it is impo

[Haskell-cafe] monadic DSL for compile-time parser generator, not possible?

It would be pretty damn cool if you could create a data type for generically describing a monadic parser, and then use template haskell to generate a concrete parser from that data type. That would allow you to create your specification in a generic way and then target different parsers like parsec

Re: [Haskell-cafe] cabal install oddities

On Tue, Mar 12, 2013 at 03:28:08PM -0400, Brandon Allbery wrote: > > "cabal install" unpacks a package into /tmp in order to build it. My guess > is your OS has /tmp mounted noexec. I don't know offhand how you override > this in cabal. Yep, you're exactly right. Thank you! I also couldn't figure

Re: [Haskell-cafe] cabal install oddities

On Tue, Mar 12, 2013 at 3:21 PM, Tycho Andersen wrote: > Below is some sample output from a failing package: > > ps168825:~/playground$ cabal install network > Resolving dependencies... > Configuring network-2.4.1.2... > configure: WARNING: unrecognized options: --with-compiler, --with-gcc > chec

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

The problem with all of these suggestions is that they start from no code. I believe Brent is looking for an *existing* project which needs contributions. I assume so that beginning Haskellers can learn real code style in the middle to large, and get input from existing community members. Kris

[Haskell-cafe] cabal install oddities

Hi all, I'm having some strange issues with cabal install. Some packages installed via `cabal install $foo` are failing for strange (and seemingly unrelated) reasons, but install just fine when I do something like: cabal unpack network cd network cabal configure cabal install Below is so

Re: [Haskell-cafe] Overloading

On Tue, Mar 12, 2013 at 3:21 PM, Brandon Allbery wrote: > On Tue, Mar 12, 2013 at 1:52 PM, Carlos Camarao > wrote: > >> Sorry, I think my sentence: >> "To define (+) as an overloaded operator in Haskell, >> you have to define and use a type class." >> is not quite correct. I meant that

Re: [Haskell-cafe] Overloading

On Tue, Mar 12, 2013 at 1:52 PM, Carlos Camarao wrote: > Sorry, I think my sentence: > "To define (+) as an overloaded operator in Haskell, > you have to define and use a type class." > is not quite correct. I meant that to define any operator in Haskell you > have to > have a type clas

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

2013/3/11 Brent Yorgey : > Hi everyone, > > I am currently teaching a half-credit introductory Haskell class for > undergraduates. This is the third time I've taught it. Both of the > previous times, for their final project I gave them the option of > contributing to an open-source project; a cou

Re: [Haskell-cafe] Overloading

On 12/03/2013, at 3:15 AM, Carlos Camarao wrote: >> Hi, >> >> I just started playing around a bit with Haskell, so sorry in >> advance for very basic (and maybe stupid) questions. Coming from >> the C++ world one thing I would like to do is overloading >> operators. For example

Re: [Haskell-cafe] newtype a Constraint?

Neat, thanks! Roman * Gábor Lehel [2013-03-12 14:26:38+0100] > {-# LANGUAGE UndecidableInstances #-} > > class OldConstraint a => NewtypedConstraint a > instance OldConstraint a => NewtypedConstraint a > > perhaps? > > Nice thing is you don't even need to do wrapping/unwrapping, like you do >

Re: [Haskell-cafe] newtype a Constraint?

{-# LANGUAGE UndecidableInstances #-} class OldConstraint a => NewtypedConstraint a instance OldConstraint a => NewtypedConstraint a perhaps? Nice thing is you don't even need to do wrapping/unwrapping, like you do with data newtypes. On Tue, Mar 12, 2013 at 2:18 PM, Roman Cheplyaka wrote: >

[Haskell-cafe] newtype a Constraint?

Is there a way to newtype a constraint? Imagine a type class parameterised over constraints. What do I do if I want multiple instances for (essentially) the same constraint? Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskel

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

On 12 March 2013 22:46, Tim Docker wrote: > On 12/03/13 05:26, Jason Dagit wrote: >> >> >> Myself and several of my friends would find it useful to have a plotting >> library that we can use from ghci to quickly/easily visualize data. >> Especially if that data is part of a simulation we are toyin

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

On 12/03/13 05:26, Jason Dagit wrote: Myself and several of my friends would find it useful to have a plotting library that we can use from ghci to quickly/easily visualize data. Especially if that data is part of a simulation we are toying with. Therefore, this proposal is for: A gnuplot-, m

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

Question is: does the task even have to involve the the production of Haskell code? Is it possible that both the student and the community-at-large would benefit further from expository-style artifacts? Some possible activities: (1) producing documentation for popular packages that cater to diff

[Haskell-cafe] ANNOUNCE xml-conduit-generic

Hello, cafe! I made a package xml-conduit-generic to provide conversion from ADT to xml and vice versa. Conversion works as Conduit (ToXml) or Consumer (FromXml). Example: data T4 = T4 {v4 :: Int, n4 :: Maybe T4} deriving (Eq, Show, Generic) instance T

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

There's the "doctest" package: http://hackage.haskell.org/package/doctest, which looks pretty good and has a number of users (35 direct reverse deps). It has support for cabal test integration, although I would like to see better integration with other test tools. But that can be added in the tes

Re: [Haskell-cafe] Open-source projects for beginning Haskell students?

I also support this suggestion. Although, do we have the build infrastructure for this?! Edward Excerpts from Michael Orlitzky's message of Mon Mar 11 19:52:12 -0700 2013: > On 03/11/2013 11:48 AM, Brent Yorgey wrote: > > > > So I'd like to do it again this time around, and am looking for > > p