[Haskell-cafe] Using "syntactic" to implement the lambda calculus

(This is intended as a simplification of the problem I actually need to solve.) I'm trying to implement the lambda calculus (with CBV evaluation) using the "syntactic" package, in such a way that a simple extension is also simple to implement. I am stuck on the fact that it seems that the Value t

[Haskell-cafe] Using Data Types a la Carte

I'm trying to implement a set of languages with a large overlap between them. From what I understand, there are 3 main ways to do this: Finally Tagless, Data Types a la Carte, or manually. I'm currently leaning toward DTalaC, but not strongly. There seem to be two packages which implement the DT

[Haskell-cafe] Is there a DFA library?

I couldn't find one on hackage that isn't better described as a RegEx library. I'm looking for things like minimization, completion, etc. kinda like http://www.cis.upenn.edu/~cis639/docs/xfst.html However, I may have just missed it. -- Alex R __

Re: [Haskell-cafe] yi + cabal-dev

not and then behaves differently. While amusing, I'd rather not. On Wed, Jun 22, 2011 at 3:42 AM, Rogan Creswick wrote: > On Tue, Jun 21, 2011 at 11:59 PM, Alex Rozenshteyn > wrote: > > From looking at Yi's code, there seems to be a hard-coded list of > arguments > > t

Re: [Haskell-cafe] yi + cabal-dev

>From looking at Yi's code, there seems to be a hard-coded list of arguments to pass to ghc. A hack would be to recompile Yi with the arguments to use a different package database... On Wed, Jun 22, 2011 at 2:32 AM, Rogan Creswick wrote: > On Tue, Jun 21, 2011 at 6:55 PM, Alex

Re: [Haskell-cafe] Category theory as a design tool

Funny, I didn't hear anyone say "Candlejack". What abou ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

[Haskell-cafe] yi + cabal-dev

I'm trying to run yi. More precisely, I'm trying to run yi in its own sandbox, created by cabal-dev. yi uses dyre to recompile its config file. Unsurprisingly, this fails, since ghc doesn't know anything about the yi install unless pointed to a separate package database. Has anyone gotten a simi

Re: [Haskell-cafe] Erlang's module discussion

Since no-one has yet mentioned it, and I think it might be relevant, http://types.bu.edu/seminar-modularity/first-class-modules-for-haskell.pdf I haven't read it with any degree of understanding, but I don't think it's tractable to remove modules from haskell, nor desirable. On Sat, May 28, 2011

Re: [Haskell-cafe] Parsing Haskell in Parsec

Thank you, everyone, for the suggestions. On Mon, Mar 21, 2011 at 12:28 PM, Johannes Waldmann < waldm...@imn.htwk-leipzig.de> wrote: > Alex Rozenshteyn gmail.com> writes: > > > as part of a larger project of porting > > http://www.cs.jhu.edu/~scott/pl/book/dist/ from

[Haskell-cafe] Parsing Haskell in Parsec

I'm trying to write a parser for a small functional language in Parsec, as part of a larger project of porting thisfrom ocaml to Haskell. I was wondering if there was a parser for Haskell written in Parsec that I could use as a reference. --

Re: [Haskell-cafe] parsing exercise

You might want to check out parsec, and the chapter related to it in RWH. http://book.realworldhaskell.org/read/using-parsec.html On Sun, Jan 23, 2011 at 12:09 AM, Sebastian Fischer wrote: > Hello, > > I need a function and wonder whether I can copy some existing code so I > don't have to write

Re: [Haskell-cafe] What's the best seed for random API ?

Admittedly, I don't know much about this from the haskell end or about the particular api. If you want statistical randomness, your seed doesn't matter; just the PRNG. I might even have seeded with a constant or taken the seed from the user. Seeding from urandom will make your output "more rando

Re: [Haskell-cafe] Question about TagSoup

I really wouldn't use tag soup for this. Haskell has libraries specifically for XML processing which might be better suited to your needs. On Fri, Dec 3, 2010 at 5:59 AM, David Virebayre > wrote: > Hello café, > > I have seen tutorials about extracting information from a tag soup, but I > have

Re: [Haskell-cafe] Layered maps

Hmm. It seems that both the trie packages I found just provide a standard map-like interface, without exposing their trie-ness. Makes sense, but limits usefulness for me. Thanks. On Sat, Oct 9, 2010 at 3:08 PM, Jake McArthur wrote: > What you describe sounds like a perfect job for a trie, so t

Re: [Haskell-cafe] Layered maps

This came up as I was doing homework for natural language processing. I'm constructing a trigram model from training data, but I also need the bigram and unigram counts. I could, for each triple of characters, add the 3 tuple to a trigram map and increment its count (I know I'm not actually mutat

[Haskell-cafe] Layered maps

Does there exist a library which allows me to have maps whose elements are maps whose elements ... with a convenient syntax. Alternatively, does there exist a library like Data.Tree where forests are sets rather than lists? -- Alex R ___ Hask

[Haskell-cafe] Memoization/call-by-need

I feel that there is something that I don't understand completely: I have been told that Haskell does not memoize function call, e.g. > slowFib 50 will run just as slowly each time it is called. However, I have read that Haskell has call-by-need semantics, which were described as "lazy evaluation

Re: [Haskell-cafe] random-fu confusion

fer to use the > "sample" function for this purpose, as well as the "sampleFrom" function in > place of runRVar/runRVarT. GHCi does not display the "sample" functions' > types properly - they are defined for RVarT as well as for all Distribution > ins

[Haskell-cafe] random-fu confusion

I seem to be having confusion at the runRVar level of random-fu. I can't figure out how to use the Data.Random.Source.PureMT module to get a meaningful random source (I can't get my code to type-check). I wrote a [trivial] flipCoin function > flipCoin = uniform False True and am trying to fill in

[Haskell-cafe] Partial Signatures with Implicit Parameters

I would like to specify that a function takes implicit parameters, without specifying its full return type. My main motivation for this is my xmonad config file and the attempt to remove the need for NoMonomorphismRestriction and some of the code smell associated with global variables that wafts i

Re: [Haskell-cafe] Deprecated gtk2hs functions

is just a > point in case, but it applies generally. > > any comments? > > andrew > > > On Fri, 2010-07-16 at 17:44 -0400, Alex Rozenshteyn wrote: > > More like buttonActivated [1]. > > > > > > Has it been decided that button-specific events are going t

Re: [Haskell-cafe] Can we come out of a monad?

Here is my understanding with respect to the question. In the general case, you cannot come out of a monad, because the monad typeclass does not include any functions without of the form (m a -> a). Also, as a category theoretic construct, a monad does not have to have an exit function. (caveat:

Re: [Haskell-cafe] Deprecated gtk2hs functions

[1] > http://www.haskell.org/gtk2hs/docs/current/Graphics-UI-Gtk-Abstract-Widget.html#v%3AexposeEvent > > > On Fri, Jul 16, 2010 at 11:36 AM, Alex Rozenshteyn > wrote: > > I recently started playing around with gtk2hs. > > I noticed that `onClicked`, `afterClicked`, etc.

[Haskell-cafe] Deprecated gtk2hs functions

I recently started playing around with gtk2hs. I noticed that `onClicked`, `afterClicked`, etc. functions have been deprecated, presumably in favor of the `on` and `after` functions in the Glib signals module, but I couldn't find a collection of the appropriate signals to replace the functionality.

Re: [Haskell-cafe] Haskell on Debian

ng the building phase. The exception was: ExitFailure 1 On Mon, Apr 5, 2010 at 11:25 AM, Daniel Fischer wrote: > Am Montag 05 April 2010 17:19:35 schrieb Alex Rozenshteyn: > > Anyone? > > "base" isn't listed among the build-depends of the executable, so the > obvious t

Re: [Haskell-cafe] Haskell on Debian

Anyone? On Wed, Mar 31, 2010 at 9:18 PM, Alex Rozenshteyn wrote: > $ ghc-pkg check > > outputs nothing > > $ ghc-pkg list unix > /var/lib/ghc-6.12.1/package.conf.d >unix-2.4.0.0 > /home/alex/.ghc/x86_64-linux-6.12.1/package.conf.d > > "unix" appears to

Re: [Haskell-cafe] Re: True Random Numbers

Looking over the random-fu package, I think it might have what I'm looking for (and a lot that I'm not). On Sat, Apr 3, 2010 at 6:27 PM, Gökhan San wrote: > Alex Rozenshteyn writes: > > > The Rand monad you linked seems to be a step in the right direction > >

Re: [Haskell-cafe] Re: True Random Numbers

The Rand monad you linked seems to be a step in the right direction for what I want, but it uses getStdGen, which appears to end up using cpu time to seed the generator. On Sat, Apr 3, 2010 at 9:21 AM, Ertugrul Soeylemez wrote: > Matthew Hayden wrote: > > > What's wrong with the System.Random.S

[Haskell-cafe] True Random Numbers

Does haskell have a way of using /dev/random to generate random *things*? Currently I'm just reading the data into a byte string, converting it into bits, and keeping track of it in the state monad. -- Alex R ___ Haskell-Cafe mailing list Haske

Re: [Haskell-cafe] Haskell on Debian

bot" Adding "unix" to the second build-depends appears to fix the error (but now it complains that base is hidden). On Wed, Mar 31, 2010 at 8:48 PM, Ivan Miljenovic wrote: > On 1 April 2010 11:42, Alex Rozenshteyn wrote: > > Main.hs:11:7: > > Could not find module

[Haskell-cafe] Haskell on Debian

I tend to install haskell packages from apt whenever possible. One such package is "unix", which appears to come provided by the ghc6 debian package. I'm trying to cabal install lambdabot and getting the following: $ cabal install lambdabot Resolving dependencies... Configuring lambdabot-4.2.2.1

Re: [Haskell-cafe] existentially quantified data types - restrictions

I think type witnesses *might* be relevant to your interests. On Thu, Mar 25, 2010 at 11:13 AM, andy morris wrote: > Can you have Typeable as an extra constraint? If so: > > > {-# LANGUAGE ExistentialQuantification #-} > > > > import Data.Typeable > > > > data Baz = forall a. (Eq a, Typeable a)