SevenThunders wrote:
Well it certainly requires some thought here. As I see it, I now have two
reasonable choices. Either I pull all my matrix operations back inside the
IO monad and avoid the matrix action as a matrix variable paradigm (due to
the loss of referential transparency) or I
Levi Stephen wrote:
Al Falloon wrote:
This code seems to indicate that you want to be able to extend the
widget types without changing this source file. This is a good goal,
but it may not be worth the extra complexity.
Ideally, I'd like Widgets to be added through hs-plugins or similar
Levi Stephen wrote:
Hi,
Apologies for a long post that may not be totally clear. I was thinking
through
a problem and how the data might be represented in Haskell. I'm now
stuck and
frustrated. Now, I'm not even sure whether I'm on the right track (I might
still be thinking too OO).
Kurt Hutchinson wrote:
On 8/15/07, Alexteslin [EMAIL PROTECTED] wrote:
I am really sorry, but i still can't define the function. The chapter the
exercise is in precedes algebraic types or Maybe a types. And is seems that
must being easy to define.
I answered some exercises on using foldr such
Chad Scherrer wrote:
I'm starting to think the power of abstraction is a blessing and a
curse. Haskell's abstraction mechanisms are so powerful that it's
generally possible to come up with a way to solve a given problem
elegantly and efficiently. On the other hand, if a problem isn't so
well
Ian Duncan wrote:
Hello everyone, I've been working on improving my Haskell knowledge, and
in doing so, I have read a little about as-patterns as well as some form
of pattern that uses ~ that I don't really understand. I suspect there
are even more lesser-known pattern matching expressions
The proposal that I like the most is this one:
Open Data Types and Open Functions
http://lambda-the-ultimate.org/node/1453
However, it doesn't readily admit using the variants as overlapping
enumerations like John suggested in a previous thread:
Mitar wrote:
Hi!
First, disclaimer: everything I know about interval arithmetics comes
from this video:
http://video.google.com/videoplay?docid=-2285617608766742834
The discussion in the implementation of the Boost Interval Arithmetic
Library is also useful.
This is the best intro to category theory I have ever heard. I finally
understand. Thank you.
Dan Piponi wrote:
I thought I'd dive in with a comment to explain why category theory is
an important subject and why it often crops up in Haskell programming.
The key thing is this: in many branches
Phlex wrote:
Christopher Lane Hinson wrote:
Where InsidenessMap a b c represents a relationship where b's are
inside a's, and b's have a state of c. Then, you need to declare a
separate InsidenessMap for each possible relationship, but this
ensures that you'll never put a galaxy inside a
Bulat Ziganshin wrote:
it seems that now we move right into this direction with GPUs
I was just thinking that GPUs might make a good target for a reduction
language like Haskell. They are hugely parallel, and they have the
commercial momentum to keep them current. It also occurred to me that
Jon Harrop wrote:
On Wednesday 30 May 2007 22:15:55 Andrew Coppin wrote:
Note that (as I understand it) GHC implements Haskell's Integer type
using the GMP. And for some reason or other, they want to remove this
feature...
Arbitrary precision integers are quite a performance burden and they
OCaml has been getting a lot of mileage from its polymorphic variants
(which allow structural subtyping on sum types) especially on problems
relating to AST transformations and the infamous expression problem.
Has there been any work on extending Haskell's type system with
structural
Mark T.B. Carroll wrote:
I don't know what the infamous expression problem is, nor am I
familiar with polymorphic variants or structural subtyping, but have you
looked at the Data.Generics.* stuff and Scrap Your Boilerplate papers?
They may be relevant.
The expression problem is a new name
apfelmus wrote:
Al Falloon wrote:
OCaml has been getting a lot of mileage from its polymorphic variants
(which allow structural subtyping on sum types) especially on problems
relating to AST transformations and the infamous expression problem.
Has there been any work on extending Haskell's
Thomas Schilling wrote:
I bring this up because I have been working on a Scheme compiler in
Haskell for fun, and something like polymorphic variants would be quite
convinent to allow you to specify versions of the AST (input ast, after
closure conversion, after CPS transform, etc.), but allow
Jon Harrop wrote:
On Thursday 31 May 2007 15:36:13 Al Falloon wrote:
I bring this up because I have been working on a Scheme compiler in
Haskell for fun, and something like polymorphic variants would be quite
convinent to allow you to specify versions of the AST (input ast, after
closure
Stefan Holdermans wrote:
Al,
Has there been any work on extending Haskell's type system with
structural subtyping?
Koji Kagawaga. Polymorphic variants in Haskell. In Andres Loeh,
editor, Proceedings of the 2006 ACM SIGPLAN Workshop on Haskell,
Portland, Oregon, USA, September 17, 2006,
Jim Burton wrote:
After posting I realised the difference between parsing (a) | (b) and
parsing a | aa ... so Parsec doesn't do the latter well or at all?
It should do (try aa) | a just fine. If you mean a general
sequence of as then (many1 (char a)) should do.
The Morse Code problem is a
Magnus Therning wrote:
On Thu, Apr 19, 2007 at 09:20:36 -0700, David Roundy wrote:
On Thu, Apr 19, 2007 at 05:37:05PM +0200, Fawzi Mohamed wrote:
I was wondering if someone had fftw bindings for haskell, or if I should
roll my own.
Not that I'm aware of, but if you roll your own, please make
Bayley, Alistair wrote:
Al Falloon wrote:
what does withSession return if there is a DBException?
Well, whatever the handler returns, same as with any other exception
handler. Note that this must have the same type as whatever withSession
returns, and this constraint is enforced by the type
Boost.Python is for extending Python with C++, or embedding Python in
C++. This is especially useful because it allows you to use Python as an
extension language for a C++ program.
Presumably Boost.Haskell would be for integrating Haskell code with C++,
which would of course be useful, but
Bulat Ziganshin wrote:
Hello Al,
Tuesday, January 30, 2007, 6:01:16 PM, you wrote:
Design of functional programs is very bottom-up. The general plan is to
identify the primitives for your domain and embed them in the language,
oh, really? may be i'm using Haskell in OOP way? :)
i strongly
Paul Moore wrote:
Now, I can protect my query with something like
main = do
withSession (connect ... ... ...) ( do
catchDB (do
-- simple query, returning reversed list of rows.
r - doQuery (sql select username from all_users) query1Iteratee []
liftIO $ putStrLn $ show r
Alexy Khrabrov wrote:
Well, I'm thinking in terms of OOD/OOA/OOP -- Design, Architecture,
Programming. That's about the only way to model a bog system. Say I
have a stock market model -- I'll have a database of tickers, a
simulator to backtest things, a trading strategy, etc.
Do Haskell
Kenneth Hoste wrote:
The idea is to gather a bunch of programs written in Haskell, and which
are representative for the Haskell community (i.e. apps, libraries,
...).
A While ago I tried to write a Haskell version of John Harrops
ray-tracer benchmark
David Roundy wrote:
On Fri, Jan 26, 2007 at 10:17:28AM -0500, Al Falloon wrote:
Kenneth Hoste wrote:
The idea is to gather a bunch of programs written in Haskell, and which
are representative for the Haskell community (i.e. apps, libraries,
...).
A While ago I tried to write a Haskell version
John Ky wrote:
Is there a built-in function that already does this?
Usually, when I have a question like this, I try Hoogle first:
http://www.haskell.org/hoogle/?q=%28a+-%3E+b%29+-%3E+Maybe+a+-%3E+Maybe+b
Unfortunatly, the right answer (fmap) is on the second page of results.
(I am really
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