Hi,
I have a set of functions:
f1 :: DBRecord - Maybe Int
f2 :: Int - IO Maybe DBRecord
f3 :: DBRecord - Maybe Int
The odd numbered functions are field accessors, accessing a field that
might hold an identifier for another record. The even numbered functions
are record fetch functions that
OK, there's the option of replacing working tools with hype.
It worked for C++, and it worked for Java.
Pity I don't have the slightest idea how to work up a hype for Haskell.
Who would want such a hype?
Why not simply start picking up fruits before the mainstream notices?
;-)
Hi,
I'm trying this in ghci:
let b = array (1,33) [(i,False) | i - [1..33]]
after :m Data.Array.IArray. It gives me that error message:
interactive:1:8:
No instance for (IArray a Bool)
arising from use of `array' at interactive:1:8-12
Probable fix: add an instance
Hello Joachim,
Friday, December 15, 2006, 10:31:35 PM, you wrote:
Because a mainstream language has more tools, more libraries, and an
easier job search.
once i've got job offer just because i know Haskell. although the job was
nothing common with FP, he searched programmers on this maillist
Hello Felix,
Thursday, December 14, 2006, 6:00:53 PM, you wrote:
The program isn't that well written so the overflow did not surprise me,
I expected that it might run out of memory. What did surprise me was the
*stack* overflow. I do not use recursion in my program except for a
couple of
Hello Joachim,
Friday, December 15, 2006, 11:34:09 PM, you wrote:
This problem affects all libraries, not just the Prelude.
The only solution that I know is explicit version numbering: wxHaskell
5.3.1 needs the Prelude 3.1.574, and there's a respository somewhere (on
the net or locally or
b needs a type.
[code]
Prelude Data.Array.IArray :t array
array :: (Ix i, IArray a e) = (i, i) - [(i, e)] - a i e
Prelude Data.Array.IArray let b = array (1,33) [(i,False) | i - [1..33]] ::
Array Int Bool
Prelude Data.Array.IArray :t b
b :: Array Int Bool
Prelude Data.Array.IArray b
array (1,33)
[EMAIL PROTECTED] wrote:
Is there a canonical example example that exhibits this behavior?
Yes, it was discussed back in 2003. Here's the canonical form:
g::(Show a,Show b) = a-b
g = undefined
--h :: Show a = b - a
h x = g(h x)
Both Hugs and GHC (in the pure Haskell98 mode!) are happy
Hey Mark,
How can I concisely compose these functions without having to write
a cascade of case statements such as:
case f1 rec1 of
Nothing - return Nothing
Just id1 - do
rec2 - f2 id2
return $ case rec2 of
I spent time working with cubic mappings. With two critical points, there
are Julia sets that consist of infinitely many disconnected components that
are still locally connected, corresponding two one critical point escaping
and one falling into one of the basins of attraction.
Of course that was
On Fri, Dec 15, 2006 at 10:05:38AM +, Felix Breuer wrote:
On Thu, 14 Dec 2006 15:31:54 -0800, David Roundy [EMAIL PROTECTED] wrote:
main = do putStrLn strict foldl1
print $ foldl1' (\a b - a + 1) $ [1..largenum]
putStrLn lazy foldl1
print $ foldl1 (\a
Adam Megacz [EMAIL PROTECTED] wrote in article [EMAIL PROTECTED] in
gmane.comp.lang.haskell.cafe:
Is there any work on automatic translation of code in some tiny
imperative language into Haskell code that uses the ST and/or IO
monads (or perhaps even pure functional code)?
Is it possible to
Wait, there are two monads in scene here, IO and Maybe.
The right solution is to compose them indeed. One could use the
MaybeT monad transformer defined in the 'All about monads' tutorial
[1], or we could just define the IOmaybe monad:
import Data.Traversable (mapM)
newtype IOMaybe a =
Hello!
I'd like to start programming in Haskell.
But as an industry programmer I have a hope to use Haskell in my every-day
work. Big part of my every-day work are GUI applications (in MS-Windows)
working with SQL databases (PostgreSQL on Linux servers).
My question: Is there a TRUE
On Sat, 2006-12-16 at 19:50 +0100, Waldemar Biernacki wrote:
Hello!
I'd like to start programming in Haskell.
But as an industry programmer I have a hope to use Haskell in my every-day
work. Big part of my every-day work are GUI applications (in MS-Windows)
working with SQL databases
Hi,
Take a look at http://www.haskell.org/haskellwiki/HGene which uses HSQL
and Gtk2hs. I don't have any code to release yet - only parts work and
the code is in an extreme state of flux; I am currently refactoring (see
my post on monads).
More generally you might be interested in the other
Hi Conrad,
On Mon, Dec 11, 2006 at 09:56:35AM +0900, Conrad Parker wrote:
I received the following bug report from someone trying to build HOgg
on Fedora Core 6 (FC6) with its ghc66 package. The build error is:
Could not find module `Data.Map':
it is a member of package base, which
That said, if I was writing a GUI+database thing, which doesn't do a
lot of substantial processing (more just Add/Edit/Delete buttons), I'd
definately use C# over Haskell. Haskell can do this, but you are
walking a relatively new path. On the other hand C# developers do this
day in, day out, and
On 16/12/06, Ian Lynagh [EMAIL PROTECTED] wrote:
Hi Conrad,
On Mon, Dec 11, 2006 at 09:56:35AM +0900, Conrad Parker wrote:
I received the following bug report from someone trying to build HOgg
on Fedora Core 6 (FC6) with its ghc66 package. The build error is:
Could not find module
Once I start needing to combine Maybe with other monads, I usually
take a moment to generalize the appropriate Maybe parts to MonadError
e m = m. Then we can just use the (ErrorT e IO) monad.
Nick
On 12/16/06, Pepe Iborra [EMAIL PROTECTED] wrote:
Wait, there are two monads in scene here, IO
minh thu schrieb:
With the arrival of Java, people get
used to have scores of libraries which are 'right there', just 'part'
of the java api.
Actually, the importance of libraries predates Java.
However, Java may have been the first language where writing the
libraries was a conscious
John Meacham schrieb:
I think we need some sort of signal, to show that one means I
understand why haskell doesn't allow this in general, but am interested
in a compiler specific trick or some theoretical background on the
issue rather than I am learning haskell and am somewhat confused due
to
There are several GUI libs that were started but not maintained. The
main ones that are maintained are Gtk2Hs and wxHaskell.
There is no current release of Gtk2Hs or wxHaskell for GHC 6.6 on
Windows (that i know about), in my opinion that means they are not
supported enough to actually use.
'Point free' is standard mathematical terminology for nothing more
than the style of defining functions without making direct reference
to the elements the functions act on.
This style is exemplified by category theory and the reason it's
called 'point free' rather than 'element free' is that
Hi,
Am Samstag, den 16.12.2006, 20:23 +0100 schrieb Duncan Coutts:
I don't actually know of anyone using one of the GUI libs in combination
with one of the DB libs. It's an obvious thing to do but you'll not find
a lot of pre-existing examples or infrastructure to help you.
Just for the
Hi Waldemar,
The final aim of the aproach is to get a tool in which there will be no
syntactic errors during modelling bussiness logic. Recently I've finished very
primary version of the tool (0.001:-).
Ah, now that sounds like Haskell might be good for :)
Haskell isn't great at writing a
On Sat, Dec 16, 2006 at 10:40:10PM +0100, Joachim Durchholz wrote:
John Meacham schrieb:
I think we need some sort of signal, to show that one means I
understand why haskell doesn't allow this in general, but am interested
in a compiler specific trick or some theoretical background on the
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