On Fri, Feb 13, 2009 at 05:21:50PM +0100, Thomas Davie wrote:
Hey,
Thanks for all the suggestions. I was hoping that there was some
uniform
pattern that would extend to n arguments (rather than having to use
liftM2, litM3, etc. or have different 'application' operators in
between
Hi Conor,
Will this do?
http://www.haskell.org/haskellwiki/Idiom_brackets
You get to write
iI f a1 a2 a3 Ji
for
do x1 - a1
x2 - a2
x3 - a3
f a1 a2 a3
amongst other things...
Cool :-) I had seen those idiom brackets before and put them on my
mental
Hello!
There was a new HaskellDB release, but I didn't see any announcement
here. Is it back alive? What happened to 0.11?
Thanks =)
--
Felipe.
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Haskell-Cafe@haskell.org
Hello,
2009/2/14 Felipe Lessa felipe.le...@gmail.com:
There was a new HaskellDB release, but I didn't see any announcement
here. Is it back alive? What happened to 0.11?
Well, HaskellDB HDBC backend got updated. HaskellDB itself lacks
manpower, you can see it for yourself by browsing it's
Thank you Benedikt!
Thanks to your help I also figured out the way to do it using type families
yesterday:
class Pro p where
type I p
type O p
re :: p → [I p → O p]
instance Pro (b → c) where
type I (b → c) = b
type O (b → c) = c
re = repeat
instance Pro [b → c] where
On Feb 13, 2009, at 6:31 PM, Krzysztof Skrzętnicki wrote:
On Fri, Feb 13, 2009 at 22:37, John A. De Goes j...@n-brain.net
wrote:
On Feb 13, 2009, at 2:11 PM, Jonathan Cast wrote:
The compiler should fail when you tell it two mutually contradictory
things, and only when you tell it two
Take, for example, this function:
f :: [Char] - Char
f [] = chr 0
f (c:cs) = chr (ord c + ord (f cs))
[] is typed as [Char], even though it could be typed in infinitely
many other ways. Demonstrating yet again, that the compiler *does* use
the additional information that it gathers to
From Fixing Haskell IO:
We can summarize the SDIOH (Standard Definition of IO in Haskell)
as a value of type IO a is a value, that performs, then delivers
a value of type a.
I think you've already made a critical mistake here. The quotes you
give all describe an IO value as something that when
On Thu, Feb 12, 2009 at 04:10:21PM +0100, Wolfgang Jeltsch wrote:
Am Donnerstag, 12. Februar 2009 15:34 schrieb Thomas DuBuisson:
Daniel Kraft asked:
That sounds interesting... What do you mean by no canonical library?
Are there already ones but just no standard one? But in this case,
Dear friends of Haskell and Functional Reactive Programming,
its my pleasure to announce the first official release of Grapefruit, a
library for Functional Reactive Programming (FRP) with a focus on user
interfaces.
With Grapefruit, you can implement reactive and interactive systems in a
Am Samstag, 14. Februar 2009 16:37 schrieb Heinrich Apfelmus:
That of course begs the question whether there is a faster but purely
No, it didn't beg any question. (Sorry for being a humourless pedant here)
functional algorithm for generating random permutations without indexes
and arrays?
Am Freitag, 13. Februar 2009 01:30 schrieben Sie:
On 12 Feb 2009, at 8:48 pm, Wolfgang Jeltsch wrote:
I don’t understand this. The way which works is conversion from
MathML to TeX.
So your suggestion would be to use MathML as the source language.
But this is
obviously not what you
Am Samstag, 14. Februar 2009 16:59 schrieb Brent Yorgey:
On Thu, Feb 12, 2009 at 04:10:21PM +0100, Wolfgang Jeltsch wrote:
Am Donnerstag, 12. Februar 2009 15:34 schrieb Thomas DuBuisson:
Get a community.haskell.org account once you are ready to start a
repo, it can not only host your repo
On Sat, Feb 14, 2009 at 9:15 AM, Stuart Cook sco...@gmail.com wrote:
From Fixing Haskell IO:
We can summarize the SDIOH (Standard Definition of IO in Haskell)
as a value of type IO a is a value, that performs, then delivers
a value of type a.
I think you've already made a critical
Am Freitag, 13. Februar 2009 17:16 schrieb Peter Verswyvelen:
Can all functional dependencies be completely replaced with associated
types when using GHC 6.10.1?
It might be possible as long as you don’t use overlapping instances. With
overlapping instances, it’s typically not possible since
it was on MS.NET 3.5
now the problem was the following
the problematic object encapsulated a running timer. on each tick of the
timer, I added an occurrence to a stream
this stream was used in another thread, but the stream itself had no
backpointer to the object that generated it
so the object
felipe.lessa:
Hello!
There was a new HaskellDB release, but I didn't see any announcement
here. Is it back alive? What happened to 0.11?
Thanks =)
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskelldb-0.12
___
Haskell-Cafe mailing
John A. De Goes wrote:
Take, for example, this function:
f :: [Char] - Char
f [] = chr 0
f (c:cs) = chr (ord c + ord (f cs))
[] is typed as [Char], even though it could be typed in infinitely many
other ways. Demonstrating yet again, that the compiler *does* use the
additional
g9ks157k:
Am Samstag, 14. Februar 2009 16:59 schrieb Brent Yorgey:
On Thu, Feb 12, 2009 at 04:10:21PM +0100, Wolfgang Jeltsch wrote:
Am Donnerstag, 12. Februar 2009 15:34 schrieb Thomas DuBuisson:
Get a community.haskell.org account once you are ready to start a
repo, it can not only
On Sat, Feb 14, 2009 at 3:18 PM, Peter Verswyvelen bugf...@gmail.com wrote:
Do you think this is something to report as a bug to Microsoft?
But this is a bit off topic in Haskell Cafe :-)
I don't know how MS treats bug reports, but if you can make a small
test case, then you should. It would
Peter Verswyvelen wrote:
Consider the following code
stamp v x = do
t - getCurrentTime
putMVar v (x,t)
Is it possible - with GHC - that a thread switch happens after the t
- getCurrentTime and the putMVar v (x,t)?
If so, how would it be possible to make sure that the operation of
If you have two streams of time/value pairs - using MVars as write-once
sampling variables - and both streams are fed from another thread (e.g.
timers firing), and you want to merge these two streams into a single stream
with monotonic time stamps, then you want to be able to check if at time t
an
Dear Group,
When trying to run the example at:
http://www.cs.vu.nl/boilerplate/testsuite/gzip/Main.hs
ghc 6.10.1 says
A pattern type signature cannot bind scoped type variables `a'
unless the pattern has a rigid type context
In the pattern: f :: a - a - a
In the definition of
I'm pretty sure that the problem is decidable, at least with haskell
98 types (other type extensions may complicate things a bit). It ends
up being a graph unification algorithm. I've tried some simple
algorithms and they seem to work.
What do you mean by the inference engine is only half of the
On Sat, Feb 14, 2009 at 7:56 AM, John A. De Goes j...@n-brain.net wrote:
Don't overlook the advantages of using familiar operators and names: you
have some intuition about '+' and 'map', so if you see them, then you'll
have some idea what they do (assuming the author is neither stupid nor
* Wolfgang Jeltsch g9ks1...@acme.softbase.org [2009-02-14 17:19:09+0100]
Dear friends of Haskell and Functional Reactive Programming,
its my pleasure to announce the first official release of Grapefruit, a
library for Functional Reactive Programming (FRP) with a focus on user
interfaces.
2009/2/13 Peter Verswyvelen bugf...@gmail.com:
No the error I got was
Could not deduce (Controller m v c)
from the context (Controller m v c2)
arising from a use of `MVC' at NM8\GUI\PanZoom.hs:126:32-65
Possible fix:
add (Controller m v c) to the context of the constructor
Always wanted to have an full-color rotating vector based ascii art
lambda on your terminal? This is your chance, installing `haha' will
do the trick!
This is very minimal vector based ascii art library written just for
fun. There is a sample program called `rotating-lambda' which does
Thanks Ryan.
I'm always struggling with functional dependencies since to be honest - I
don't really understand how the type inferer figures out all the types and I
didn't take the time to study it yet. Your email will help me a bit further
with this.
My functional dependency was c - m v. It can't
One of the things I liked a lot when working with C# was that as soon as my
code compiled, it usually worked after an iteration of two.At least if we
forget about the nasty imperative debugging that is needed after a while
because of unanticipated and unchecked runtime side effects.
After heaving
On Sat, 14 Feb 2009, Daniel Fischer wrote:
Am Samstag, 14. Februar 2009 16:37 schrieb Heinrich Apfelmus:
For the full exposition, see
http://apfelmus.nfshost.com/random-permutations.html
Excellent work, thanks.
Interesting read.
Btw. a further development of the PFP library is also
On Sun, Feb 15, 2009 at 12:51:38AM +0100, Peter Verswyvelen wrote:
However, it is just amazing that whenever my Haskell program compiles (which
to be fair can take a while for an average Haskeller like me ;-), it just...
works! I have heard rumors that this was the case, but I can really
I have been learning Haskell for the last two weeks and was relaying that
exact benefit to my friend in attempts to convert him. I spend 3 hours
getting a few functions to compile, but when they do, they just work. Every
time.
2009/2/14 Peter Verswyvelen bugf...@gmail.com
One of the things I
Artyom Shalkhakov wrote:
Is anybody planning to use these shiny new ways for doing IO?
Interesting that you ask. I am currently using the 'lightweight monadic
region' approach to manage network resources (so called 'channels',
connections to a named variable; the context is Haskell support for a
As this topic popped out, my secrets for programming in Haskell are
three words: assert, HUnit, QuickCheck.
- Create internal functions that verify the results of the exported
ones, or maybe an easier to verify implementation that is slower, and
put them on assert's. This has saved me a few
sfvisser:
Always wanted to have an full-color rotating vector based ascii art
lambda on your terminal? This is your chance, installing `haha' will do
the trick!
This is very minimal vector based ascii art library written just for
fun. There is a sample program called `rotating-lambda' which
2009/2/14 Peter Verswyvelen bugf...@gmail.com
If you have two streams of time/value pairs - using MVars as write-once
sampling variables - and both streams are fed from another thread (e.g.
timers firing), and you want to merge these two streams into a single stream
with monotonic time
Chung-chieh Shan wrote:
wren ng thornton wrote:
It's ugly, but one option is to just reify your continuations as an ADT,
where there are constructors for each function and fields for each
variable that needs closing over. Serializing that ADT should be simple
(unless some of those
2009/2/14 Peter Verswyvelen bugf...@gmail.com
One of the things I liked a lot when working with C# was that as soon as my
code compiled, it usually worked after an iteration of two.At least if we
forget about the nasty imperative debugging that is needed after a while
because of unanticipated
At Sun, 15 Feb 2009 05:37:12 +,
Sebastian Sylvan wrote:
So my conclusion is that it's not just static typing, it's functional
programming in conjunction with static strong type checking.
Indeed. For example, it's pretty hard to accidentally use an
'uninitialized variable' in Haskell,
John A. De Goes wrote:
On Feb 13, 2009, at 2:11 PM, Jonathan Cast wrote:
The compiler should fail when you tell it two mutually contradictory
things, and only when you tell it two mutually contradictory things.
By definition, it's not a contradiction when the symbol is unambiguously
2009/2/15 Sebastian Sylvan syl...@student.chalmers.se:
2009/2/14 Peter Verswyvelen bugf...@gmail.com
One of the things I liked a lot when working with C# was that as soon as
my code compiled, it usually worked after an iteration of two.At least if we
forget about the nasty imperative debugging
Hello,
2009/2/15 Michael D. Adams mdmko...@gmail.com:
Has anyone seen any real studies of this phenomenon? There is plenty
of anecdotal evidence that Haskell is doing something right to reduce
the bugs
Let's just call it a miracle of FP, write many books and articles on
the matter
(i.e.,
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