Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

On Wed, Feb 20, 2008 at 10:46 PM, <[EMAIL PROTECTED]> wrote: > Quoting Neil Mitchell <[EMAIL PROTECTED]>: > > > Yes, its the projection onto another type: > > > > [] = Nothing > > (x:xs) = Just (x, xs) > > Also known as msplit: > > http://www.haskell.org/haskellwiki/New_monads/MonadSpli

Re: [Haskell-cafe] Selecting Array type

On 2/19/08, Ryan Ingram <[EMAIL PROTECTED]> wrote: > > Oleg's done a lot of work here; there's a bunch of magic that can be > done with TypeCast. I took my inspiration from here: > http://okmij.org/ftp/Haskell/typecast.html#ambiguity-resolution > . . . > > The trick is to represent whether a typ

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

> I would expect my (well, I didn't invent it) to work better on something that didn't have this unique structure, such as: > test 0 = Var 0 > test n | even n= Or (Var n) (test (n-1)) > | otherwise = And (test (n-1)) (Var n) for some reason this still does not perform as well as it shou

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

[EMAIL PROTECTED]:~/workspace/Haskell-1/bin$ time ./theResult sert 101 real0m1.384s user0m1.148s sys 0m0.112s [EMAIL PROTECTED]:~/workspace/Haskell-1/bin$ time ./theResult bromage 101 real0m2.240s user0m1.972s sys 0m0.176s [EMAIL PROTECTED]:~/workspace/Haskell-1/

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

G'day all. Quoting Cetin Sert <[EMAIL PROTECTED]>: It is astonishing to see that your version actually performs the worst (at least on my machine). On your example, I'm not surprised: plong 0 = Var 0 plong n | even n= Or (Var n) (plong (n-1)) | otherwise = And (Var n) (plong (n

Re: [Haskell-cafe] The Proliferation of List-Like Types

On Wednesday 20 February 2008 8:42:56 pm Roman Leshchinskiy wrote: > John Goerzen wrote: > > I am concerned that the same thing is happening in Haskell. We know > > have three common list-like types: the regular list, strict > > ByteString, and lazy ByteString. > > Why do you consider ByteString t

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

On Thu, 2008-02-21 at 05:10 +0100, Cetin Sert wrote: > plong 0 = Var 0 > plong n | even n= Or (Var n) (plong (n-1)) > | otherwise = And (Var n) (plong (n-1)) compare the times again but with plong as follows: plong 0 = Var 0 plong n | even n = Or (plong (n-1)) (Var n) | otherw

Re: [Haskell-cafe] A little toy of Haskell Trivia

On Thu, 21 Feb 2008, Wolfgang Jeltsch wrote: > Am Mittwoch, 20. Februar 2008 22:22 schrieb Steve Lihn: > > I proudly announce a little toy that lists the frequency of modules > > being imported by other modules. Do you know Control.Monad is the most > > frequently imported module? I did not! > >

Re: [Haskell-cafe] question about STM and IO

I take it that this follows from the lack of any mechanism to rollback IO? If so, I think that the following guidelines suffice for when it's acceptable to use unsafeIOtoSTM: 1. The IO action must be able to be safely repeated. 2. The IO action must be able to be safely performed with possibly-

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

plong 0 = Var 0 plong n | even n= Or (Var n) (plong (n-1)) | otherwise = And (Var n) (plong (n-1)) main = do print ((length ∘ vars) (plong 1000)) real0m3.290s user0m3.152s sys 0m0.020s main = do print ((length ∘ vars_) (plong 1000)) real0m3.732s user0m3.68

Re: [Haskell-cafe] The Proliferation of List-Like Types

On Thu, 21 Feb 2008, Roman Leshchinskiy wrote: > John Goerzen wrote: > > > 2) Would it make sense to make ListLike, or something like it, > >part of the Haskell core? > > I don't think ListLike is the right approach. It's basically a fairly > arbitrary collection of functions. It would be pre

[Haskell-cafe] Re: The Proliferation of List-Like Types

On Wed, 20 Feb 2008, Chad Scherrer wrote: > On Feb 20, 2008 10:57 AM, Antoine Latter <[EMAIL PROTECTED]> wrote: > > For anyone looking into it - the StorableVector fusion would have to > > be quite different from the current ByteString fusion framework. > > Maybe it would be enough to lay down a

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

G'day all. Quoting Neil Mitchell <[EMAIL PROTECTED]>: Yes, its the projection onto another type: [] = Nothing (x:xs) = Just (x, xs) Also known as msplit: http://www.haskell.org/haskellwiki/New_monads/MonadSplit Cheers, Andrew Bromage ___ Hask

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

G'day all. Quoting Cetin Sert <[EMAIL PROTECTED]>: -- proposition data Prp a = Var a | Not (Prp a) | Or (Prp a) (Prp a) | And (Prp a) (Prp a) | Imp (Prp a) (Prp a) | Xor (Prp a) (Prp a) | Eqv (Prp a) (Prp a) | Cns Boo

Re: [Haskell-cafe] A little toy of Haskell Trivia

Rewriting that script in Haskell could be an interesting exercise. Do you have the source code? Benjamin L. Russell --- Steve Lihn <[EMAIL PROTECTED]> wrote: > I proudly announce a little toy that lists the > frequency of modules > being imported by other modules. Do you know > Control.Monad is

Re: [Haskell-cafe] what is the fastest way to extract variables from a proposition?

It depends what you mean by "faster"; more efficient (runtime) or less typing (programmer time!) For the former, you have basically the best implementation there is; you are basically encoding the continuation of (++) into the accumulating list of arguments to evs. You might want to consider diff

Re: [Haskell-cafe] The Proliferation of List-Like Types

John Goerzen wrote: I am concerned that the same thing is happening in Haskell. We know have three common list-like types: the regular list, strict ByteString, and lazy ByteString. Why do you consider ByteString to be list-like but not arrays? 1) Does everyone agree with me that we have a p

Re: [Haskell-cafe] question about STM and IO

On 2/20/08, Bulat Ziganshin <[EMAIL PROTECTED]> wrote: > STM operations can be repeated if first transaction was unsuccessful. > so, you may se here only operations that may be safely repeated - say, > reading/writing memory areas, or reading/writing files, or even > sending network message as long

Re: [Haskell-cafe] stream/bytestring questions

Chad Scherrer wrote: Here's an example of the problem. Start with a function extract :: [Int] -> [a] -> [a] extract = f 0 where f !k nss@(n:ns) (x:xs) | n == k= x : f (k+1) ns xs | otherwise = f (k+1) nss xs f _ _ _ = [] If you want this to play nicely with stream

Re: [Haskell-cafe] Selecting Array type

Oleg's done a lot of work here; there's a bunch of magic that can be done with TypeCast. I took my inspiration from here: http://okmij.org/ftp/Haskell/typecast.html#ambiguity-resolution Here are some tests in ghci (note that I specialized the index type in "test" to Int to make this shorter; doin

Re: [Haskell-cafe] The Proliferation of List-Like Types

On Wednesday 20 February 2008 5:13:34 pm Duncan Coutts wrote: > On Wed, 2008-02-20 at 08:39 -0600, John Goerzen wrote: > > * The iconv library works only on lazy ByteStrings, and does not > >handle Strings or strict ByteStrings > > There is a very good reason for this. The right solution in thi

[Haskell-cafe] Re: Where does ~> come from?

Stefan O'Rear wrote: > On Wed, Feb 20, 2008 at 07:18:42PM -0500, Steve Lihn wrote: >> If ~> does not have any special meaning and it could be ### or xyz, >> then how does GHC know to print >> a ~> b, but not ~> a b >> a ### b, but not ### a b >> xyz a b, but not a `xyz` b >> >> Simply because x

[Haskell-cafe] haddock as a markdown preprocessor

There was a chat today on #haskell (15:08 to 16:10) about evolving haddock. I'd like to get comments. The goal is to get the full functionality of a general purpose, programmer-friendly markup language like markdown. One example is image embedding.

Re: [Haskell-cafe] Haddock documentation of Data.Array.* is confusing

On Wed, Feb 20, 2008 at 10:17 PM, Bulat Ziganshin <[EMAIL PROTECTED]> wrote: > Hello Alfonso, > > > Tuesday, February 12, 2008, 11:32:20 PM, you wrote: > > > Excuse me for the subject, but IMHO is absolutely true. Anyhow, the > > of course, you are right, but for practical goals i may suggest ju

Re: [Haskell-cafe] Where does ~> come from?

On Wed, Feb 20, 2008 at 07:18:42PM -0500, Steve Lihn wrote: > If ~> does not have any special meaning and it could be ### or xyz, > then how does GHC know to print > a ~> b, but not ~> a b > a ### b, but not ### a b > xyz a b, but not a `xyz` b > > Simply because xyz is alphanumeric? Yes. Ste

Re: [Haskell-cafe] Where does ~> come from?

If ~> does not have any special meaning and it could be ### or xyz, then how does GHC know to print a ~> b, but not ~> a b a ### b, but not ### a b xyz a b, but not a `xyz` b Simply because xyz is alphanumeric? On Wed, Feb 20, 2008 at 12:34 AM, David Menendez <[EMAIL PROTECTED]> wrote: > On F

Re: [Haskell-cafe] A little toy of Haskell Trivia

On Wed, Feb 20, 2008 at 09:22:58PM +, Steve Lihn wrote: > I proudly announce a little toy that lists the frequency of modules > being imported by other modules. Do you know Control.Monad is the most > frequently imported module? I did not! > > Currently it only includes GHC 6.8 core library. I

Re: [Haskell-cafe] A little toy of Haskell Trivia

Am Mittwoch, 20. Februar 2008 22:22 schrieb Steve Lihn: > I proudly announce a little toy that lists the frequency of modules > being imported by other modules. Do you know Control.Monad is the most > frequently imported module? I did not! This doesn’t surprise me very much. What surprises me mor

Re: [Haskell-cafe] Haddock documentation of Data.Array.* is confusing

Hello Alfonso, Tuesday, February 12, 2008, 11:32:20 PM, you wrote: > Excuse me for the subject, but IMHO is absolutely true. Anyhow, the of course, you are right, but for practical goals i may suggest just to read module sources instead of reading [had]docs. seeing the implementation is much mor

Re: [Haskell-cafe] question about STM and IO

Hello John, Tuesday, February 12, 2008, 9:28:22 PM, you wrote: > I was recently looking at the STM library, and I have a question about > the function "unsafeIOToSTM". Can anyone explain to me what is unsafe > about it, and what sort of use would be considered "safe"? STM operations can be repea

Re: [Haskell-cafe] The Proliferation of List-Like Types

On Wed, 2008-02-20 at 08:39 -0600, John Goerzen wrote: > * The iconv library works only on lazy ByteStrings, and does not >handle Strings or strict ByteStrings There is a very good reason for this. The right solution in this particular example is not to overload every internal string operati

[Haskell-cafe] Re: The Proliferation of List-Like Types

On 2008-02-20, John Goerzen <[EMAIL PROTECTED]> wrote: > > On the other hand, if you mean using a dictionary to "wrap" just the > ByteString types (or other similar ones), I am currently thinking of > something along those lines. I'll post here if I come up with > something clever (or not). Can't

[Haskell-cafe] Re: Re: The Proliferation of List-Like Types

David Roundy wrote: > On Wed, Feb 20, 2008 at 11:18:51PM +0100, Ben Franksen wrote: >> John Goerzen wrote: >> > On 2008-02-20, Jules Bean <[EMAIL PROTECTED]> wrote: >> >> Not directly, no. >> >> >> >> The point about Foldable, Functor, and Monad, is that they enforce the >> >> connection between co

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

On Wed, Feb 20, 2008 at 11:18:51PM +0100, Ben Franksen wrote: > John Goerzen wrote: > > > On 2008-02-20, Jules Bean <[EMAIL PROTECTED]> wrote: > >> Not directly, no. > >> > >> The point about Foldable, Functor, and Monad, is that they enforce the > >> connection between container and contents. If

[Haskell-cafe] Re: The Proliferation of List-Like Types

John Goerzen wrote: > On 2008-02-20, Jules Bean <[EMAIL PROTECTED]> wrote: >> Not directly, no. >> >> The point about Foldable, Functor, and Monad, is that they enforce the >> connection between container and contents. If the contents is of type >> "a", the container is of type "f a" for a fixed t

[Haskell-cafe] Fwd: NW Functional Programming Interest Group

All, Apologies for multiple listings. This is just a friendly reminder that a small cadre of us are organizing a Northwest Functional Programming Interest Group. Our first official meeting is today at the The Seattle Public Library 1000 - 4th Ave. Seattle, WA 98104 Spiral 6 Conference Room fro

[Haskell-cafe] Re: Selecting Array type

Jeff φ wrote: > However, my implementation of SmartArray requires me to create an instance > of a selector class to tell the compiler whether the type is boxed or > unboxed. I'm hoping to avoid creating instances of the selector class for > every possible type. I'd be grateful for any suggestions

Re: [Haskell-cafe] Broken http://darcs.haskell.org/darcsweb/?

On Wed, Feb 20, 2008 at 07:28:54PM +, Dominic Steinitz wrote: > I'm getting errors when I click on any of the links. I've created /tmp/darcsweb-cache and made it writable, which seems to have made it work again. > I'm not sure who administers the site. Neither am I, but it needs some tweakin

Re: [Haskell-cafe] Exporting Haskell Libraries to C Programmers

joseph.bruce: > Hi, > > I have a Haskell library that I want to make available via FFI to C > programmers on my project team. I read this thread > (http://thread.gmane.org/gmane.comp.lang.haskell.cafe/21447) which had > some interesting ideas, but they seemed unresolved. Or maybe it answers > my

[Haskell-cafe] Re: a help for install

Wolfgang Jeltsch wrote: > Am Montag, 18. Februar 2008 19:46 schrieb Carlos Gomez A.: >> hi, my name is carlos >> >> I need information for correct installor >> >> what are dependencies on ghc ? >> >> I have a Debian System. > > Always use your distribution’s packages until they aren’t any or t

[Haskell-cafe] what is the fastest way to extract variables from a proposition?

-- proposition data Prp a = Var a | Not (Prp a) | Or (Prp a) (Prp a) | And (Prp a) (Prp a) | Imp (Prp a) (Prp a) | Xor (Prp a) (Prp a) | Eqv (Prp a) (Prp a) | Cns Bool deriving (Show, Eq) -- Here are to variab

[Haskell-cafe] A little toy of Haskell Trivia

I proudly announce a little toy that lists the frequency of modules being imported by other modules. Do you know Control.Monad is the most frequently imported module? I did not! Currently it only includes GHC 6.8 core library. If you have any idea how to parse through HackageDB code, please let me

[Haskell-cafe] Re: Arrows: definition of pure & arr

Wolfgang Jeltsch wrote: > I’m also in the process of shortening the names for type variables since > in conference papers you cannot use names that long (because otherwise you > quickly overrun the available width) and I don’t want to have too many > differences between papers and actual source cod

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

Antoine Latter <[EMAIL PROTECTED]> wrote: > From what I saw of Data.ByteString.Fusion, it relies on the assumption > that the elements of the output array are of the same size and > alignment as the elements of all of the arrays in the fused > intermediate steps. That way, all of the intermediate

[Haskell-cafe] Broken http://darcs.haskell.org/darcsweb/?

I'm getting errors when I click on any of the links. I'm not sure who administers the site. IOError Python 2.4.4: /usr/bin/python Wed Feb 20 11:41:13 2008 A problem occurred in a Python script. Here is the sequence of function calls leading up to the error, in the order they occurred. /srv/darcs

Re: [Haskell-cafe] Doubting Haskell

Cale, On Feb 20, 2008 10:58 AM, Cale Gibbard <[EMAIL PROTECTED]> wrote: > (I'm copying the list on this, since my reply contains a tutorial > which might be of use to other beginners.) Thank you so much for this - I've just started playing with it so few intelligent responses yet. I'm sure it wil

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

On Feb 20, 2008 12:59 PM, Chad Scherrer <[EMAIL PROTECTED]> wrote: > On Feb 20, 2008 10:57 AM, Antoine Latter <[EMAIL PROTECTED]> wrote: > > For anyone looking into it - the StorableVector fusion would have to > > be quite different from the current ByteString fusion framework. > > Maybe it would b

[Haskell-cafe] Re: The Proliferation of List-Like Types

On 2008-02-20, Jules Bean <[EMAIL PROTECTED]> wrote: > Not directly, no. > > The point about Foldable, Functor, and Monad, is that they enforce the > connection between container and contents. If the contents is of type > "a", the container is of type "f a" for a fixed type constructor 'f'. > Th

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

On Feb 20, 2008 10:57 AM, Antoine Latter <[EMAIL PROTECTED]> wrote: > For anyone looking into it - the StorableVector fusion would have to > be quite different from the current ByteString fusion framework. > Maybe it would be enough to lay down a Stream fusion framework for > StorableVectors. I mu

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

On Feb 20, 2008 12:48 PM, Chad Scherrer <[EMAIL PROTECTED]> wrote: > > StorableVector should fill this gap. > >http://code.haskell.org/~sjanssen/storablevector/ > > > > Yes, it could, but > (1) it's way behind ByteString in terms of optimizations (== "fusion") > (2) there's (as far as I know) n

[Haskell-cafe] Re: The Proliferation of List-Like Types

Henning Thielemann henning-thielemann.de> writes: > > 4) We are missing one final useful type: a Word32-based ByteString. > > When working in the Unicode character set, a 32-bit character > > can indeed be useful, and I could see situations in which the > > performance benefit of a ByteStrin

Re: [Haskell-cafe] stream/bytestring questions

On Feb 17, 2008 6:06 PM, Derek Elkins <[EMAIL PROTECTED]> wrote: > It's -quite- possible that a coalgebraic perspective is much more > natural for your code/problem. If that's the case, use it (the > coalgebraic perspective that is). Obviously depending on the internals > of the stream library is

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

John Goerzen wrote: On 2008-02-20, John Goerzen <[EMAIL PROTECTED]> wrote: I notice that Data.Foldable does some similar things but does not use multi-parameter type classes. I seem to recall that I attempted to do this in the same manner, but got tripped up somewhere. I can't remember now exa

Re: [Haskell-cafe] Problem with Python AST

Hi Something like this would do? if_ = Compound $ If [(IntLit 6, Suite [] [Break])] Nothing while_ = Compound $ While (IntLit 6) (Suite [] [if_]) Nothing f = Program [while_] -- this one fails -- f2 = Program [if_] newtype Ident = Id String data BinOp = Add | Sub data Exp = IntL

Re: [Haskell-cafe] Re: Implementing fixed-sized vectors (using datatype algebra?)

On Wed, Feb 20, 2008 at 11:26 AM, Wolfgang Jeltsch <[EMAIL PROTECTED]> wrote: > Hello Fons, > > why do you use the term vector? I'd say that this term is more or less wrong > for what this type is about. The distinguishing property of vectors compared > to lists is that there is addition and

[Haskell-cafe] Problem with Python AST

Hello everyone, I am trying to create an AST for Python. My approach is to create a data type for each syntactic construct. But I am stuck trying to statically enforce some constraints over my statements. A very short example to illustrate my problem: newtype Ident = Id String data BinOp = Add

Re: [Haskell-cafe] Re: The Proliferation of List-Like Types

Hi > > full -> Maybe (item, full) > > Hrm, what exactly is the return data here? Is is the head and the > tail if the list has >= 1 item, or Nothing otherwise? Or...? Yes, its the projection onto another type: [] = Nothing (x:xs) = Just (x, xs) > What is the problem with MPTC in bas

[Haskell-cafe] Re: The Proliferation of List-Like Types

On 2008-02-20, John Goerzen <[EMAIL PROTECTED]> wrote: > I notice that Data.Foldable does some similar things but does not use > multi-parameter type classes. I seem to recall that I attempted to do > this in the same manner, but got tripped up somewhere. I can't > remember now exactly what the p

[Haskell-cafe] Re: The Proliferation of List-Like Types

On 2008-02-20, Ross Paterson <[EMAIL PROTECTED]> wrote: >> conventions won't be usable in my ByteString code, for instance. >> [...] >> >> http://software.complete.org/listlike/static/doc/ListLike/Data-ListLike.html > > As Henning pointed out, multiple parameter type classes are problematic > fo

Re: [Haskell-cafe] Selecting Array type

On Wed, 20 Feb 2008, Brent Yorgey wrote: 2008/2/19 Jeff ö <[EMAIL PROTECTED]>: > instance SmartArraySelector UArray Bool where > instance SmartArraySelector UArray Char where > instance SmartArraySelector UArray Double where > instance SmartArraySelector UArray Float where > instance Sma

[Haskell-cafe] First Call for Papers -- GPCE'08

Call for Papers Seventh International Conference on Generative Programming and Component Engineering (GPCE 2008) October 19-23, 2008 Nashville, Tennessee

Re: [Haskell-cafe] Selecting Array type

2008/2/19 Jeff φ <[EMAIL PROTECTED]>: > > instance SmartArraySelector UArray Bool where > instance SmartArraySelector UArray Char where > instance SmartArraySelector UArray Double where > instance SmartArraySelector UArray Float where > instance SmartArraySelector UArray Intwhere > Well,

Re: [Haskell-cafe] The Proliferation of List-Like Types

On Wed, Feb 20, 2008 at 08:39:13AM -0600, John Goerzen wrote: > I am concerned that the same thing is happening in Haskell. We now > have three common list-like types: the regular list, strict > ByteString, and lazy ByteString. > > This has created some annoying situations. For instance, a ByteS

Re: [Haskell-cafe] The Proliferation of List-Like Types

Now, to help solve this problem, I wrote ListLike[2], providing a set of typeclasses that make list operations generic. I also provided default instances of ListLike for: ListLike Data.ByteString.ByteString Word8 ListLike Data.ByteString.Lazy.ByteString Word8 ListLike [a] a (Integral i, Ix

[Haskell-cafe] The Proliferation of List-Like Types

Hi folks, Before I started using Haskell, I used OCaml for a spell. One of my biggest annoyances with OCaml was that it had two list types: the default list (strict), and a lazy list (known as a stream). This led to all sorts of annoyances. Libraries were always written to work with one list or

Re: [Haskell-cafe] Re: Implementing fixed-sized vectors (using datatype algebra?)

Am Mittwoch, 20. Februar 2008 09:20 schrieben Sie: > OK I'll include the module after I change the things mentioned. > > BTW, I finally have an initial version of the parameterized-data package: > > Darcs repository: > > http://code.haskell.org/parameterized-data > > Haddock documentation: > > http

Re: [Haskell-cafe] Doubting Haskell

(I'm copying the list on this, since my reply contains a tutorial which might be of use to other beginners.) On 19/02/2008, Alan Carter <[EMAIL PROTECTED]> wrote: > Hi Cale, > > On Feb 19, 2008 3:48 PM, Cale Gibbard <[EMAIL PROTECTED]> wrote: > > Just checking up, since you haven't replied on the

Re: [Haskell-cafe] Re: Implementing fixed-sized vectors (using datatype algebra?)

OK I'll include the module after I change the things mentioned. BTW, I finally have an initial version of the parameterized-data package: Darcs repository: http://code.haskell.org/parameterized-data Haddock documentation: http://code.haskell.org/~fons/parameterized-data/doc/ Any comments/sugg