On 16 Feb 2008, at 11:40 PM, Peter Verswyvelen wrote:
After having played with some packages that use arrows, and after
having read the very nice programming with arrows paper I wanted
to build some of my own.
Strangely my code did not work, even the simplest function got
stuck in an
On Sun, 2008-02-17 at 02:46 -0500, Anton van Straaten wrote:
Colin Paul Adams wrote:
Cale == Cale Gibbard [EMAIL PROTECTED] writes:
Cale So, the first version:
Cale import System.IO import Control.Exception (try)
Cale main = do mfh - try (openFile myFile ReadMode)
Colin Paul Adams wrote:
Left? Right?
Hardly descriptive terms. Sounds like a sinister language to me.
The mnemonics is that Right x is right in the sense of correct. So,
the error case has to be Left err .
Regards,
apfelmus
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apfelmus == apfelmus [EMAIL PROTECTED] writes:
apfelmus Colin Paul Adams wrote:
Left? Right?
Hardly descriptive terms. Sounds like a sinister language to
me.
apfelmus The mnemonics is that Right x is right in the sense of
apfelmus correct. So, the error case
On 17 Feb 2008, at 1:12 AM, Colin Paul Adams wrote:
apfelmus == apfelmus [EMAIL PROTECTED] writes:
apfelmus Colin Paul Adams wrote:
Left? Right?
Hardly descriptive terms. Sounds like a sinister language to
me.
apfelmus The mnemonics is that Right x is right in the sense of
Alan Carter wrote:
We now need to be able to do parallel with ease. Functional
programming just got really important.
While this is a reason to have a look at Haskell, I think it's not the
best one. In fact, I think it's probably harmful to have parallelism as
single goal for learning
On 17 feb 2008, at 08.46, Anton van Straaten wrote:
Colin Paul Adams wrote:
Cale == Cale Gibbard [EMAIL PROTECTED] writes:
Cale So, the first version:
Cale import System.IO import Control.Exception (try)
Cale main = do mfh - try (openFile myFile ReadMode) case mfh
Cale of
On Sun, Feb 17, 2008 at 12:00:43AM -0800, Jonathan Cast wrote:
arr = pure
pure = arr
[...]
This example is admittedly kind of silly, but I'm sure someone has a
passionate attachment to one or both names, so requiring definitions
to use one or the other would be
This is a small package for error handling when making foreign calls
to the Windows API. The functions are similar to those in
Foreign.C.Error, e.g. throwWinErrorIf corresponds to throwErrnoIf.
Dynamic io errors are thrown with GHC so the catchWinError function
can catch specific Windows error
On Thu, Feb 14, 2008 at 04:56:39AM -0800, Grzegorz Chrupala wrote:
I have a very simple program which reads a Data.Map from a file using
Data.Binary and Data.ByteString.Lazy, which gives stack overflow with files
over a certain size. Any ideas of what might be causing it?
You can try it with
Hi
2) You would hope there is a quick way to search those symbols. But
most search engines do not treate symbols friendly, often just ignore
them. I typed ~ in Hoogle, it also returned nothing.
3) If the module defining the symbol is not in standard library, it is
not possible to look up the
I don't get why the name isn't arrow instead of arr... Arr reminds
me of pirates, arrrhh ;-)
I guess first was chosen because fst was already taken, but then it
would be logical to choose arrow instead of arr ;-)
Ross Paterson wrote:
On Sun, Feb 17, 2008 at 12:00:43AM -0800, Jonathan
On Sun, 17 Feb 2008, Anton van Straaten wrote:
Is there a benefit to reusing a generic Either type for this sort of thing?
For code comprehensibility, wouldn't it be better to use more specific
names? If I want car and cdr, I know where to find it.
It's Haskell's standard sum type, with a
Hi Richard,
On Mon, Feb 11, 2008 at 12:37:27PM +1300, Richard A. O'Keefe wrote:
On 9 Feb 2008, at 2:29 pm, Philip Weaver wrote:
GHC certain *could* do this, but it's arguably not the right thing
to do.
I have reminded the GHC maintainers before that the Haskell
specification
On Feb 17, 2008 12:13 AM, Dave Hinton [EMAIL PROTECTED] wrote:
(This is a toy program to demonstrate only the part of my real program
that I'm having trouble with.)
Suppose I'm writing a program to print the current time in various
time zones. The time zones are to be given symbolically on
Am Sonntag, 17. Februar 2008 16:09 schrieb Bjorn Bringert:
Interesting, it works for me:
$ ghc --make hsnow.hs -o hsnow
[1 of 1] Compiling Main ( hsnow.hs, hsnow.o )
Linking hsnow ...
$ ./hsnow Europe/Paris Europe/Moscow Europe/London
Europe/Paris2008-02-17 16:07:43.009057
On Feb 17, 2008, at 1:12 AM, Colin Paul Adams wrote:
And left is not the opposite of correct. That would be incorrect.
Also, it is not clear to me that a failure to read a file (for
instance) is incorrect behaviour. If the file doesn't exist, then I
think it ought to be considered correct
On Feb 17, 2008, at 13:22 , Daniel Fischer wrote:
Am Sonntag, 17. Februar 2008 17:26 schrieb Daniel Fischer:
Looking at the code in HsTime.c, it might be a difference between
localtime
and localtime_r.
Indeed, mucking about a bit with HsTime.c, so that either
a) localtime is called
Am Sonntag, 17. Februar 2008 17:26 schrieb Daniel Fischer:
Looking at the code in HsTime.c, it might be a difference between localtime
and localtime_r.
Indeed, mucking about a bit with HsTime.c, so that either
a) localtime is called instead of localtime_r
or
b) tzset() is done before
Donn Cave writes:
On Feb 17, 2008, at 1:12 AM, Colin Paul Adams wrote:
And left is not the opposite of correct. That would be incorrect.
...
If it's any consolation to those of the left handed persuasion, I guessed
it wrong - I have used Either in this way, but Left was Success and
Right
Writing a parsing library like this is a great learning experience;
Graham Hutton wrote a paper you can follow along with entitled
Monadic Parsing in Haskell at
http://www.cs.nott.ac.uk/~gmh/bib.html#pearl
But if you're just interested in writing a parser, and not in writing
a parser generator, I
Hurrah, I am now calling the C function tzset() from my Haskell code
via FFI, and I'm getting the results I want.
$ cat hsc2now.hs
{-# LANGUAGE ForeignFunctionInterface #-}
import Data.Time
import Data.Time.LocalTime
import System.Environment
import System.Posix.Env
foreign import ccall time.h
beakerchu:
Hurrah, I am now calling the C function tzset() from my Haskell code
via FFI, and I'm getting the results I want.
$ cat hsc2now.hs
{-# LANGUAGE ForeignFunctionInterface #-}
import Data.Time
import Data.Time.LocalTime
import System.Environment
import System.Posix.Env
foreign
Philip Armstrong wrote:
Since no-one else has answered, I'll take a stab.
Obiously, you have a stack leak due to laziness somewhere
I wouldn't say that was obvious, though it is certainly a
possibility.
I'm never exactly clear what people mean by a stack leak.
It seems some folk regard any
Adrian Hey wrote:
Philip Armstrong wrote:
In fact, a little experimentation has revealed that this:
do
[path] - getArgs
m - liftM decode (BS.readFile path)::IO [((Int, Maybe String), Int)]
putStrLn . show . findMax . fromAscList $ m
will work just fine. No extra evaluation needed
For a while I've been meaning to propose something along the lines of
this class:
class (MonadError m e, MonadError m' e') =
MonadErrorRelated m e m' e' | m - e, m' - e', m e' - m' where
catch' :: m a - (e - m' a) - m' a
rethrow :: m a - (e - e') - m' a
with an example instance
Bertram Felgenhauer wrote:
I'm fairly certain that the stack overflow is (indirectly) caused by
Data.Binary, not Data.Map.
Yes, I think you are right. At least it seems clear that the stack
overflow is not directly caused by fromDistinctAscList.
The result of 'decode' is a list of known
Matthew Naylor [EMAIL PROTECTED] wrote in article [EMAIL PROTECTED] in
gmane.comp.lang.haskell.cafe:
sklansky f [] = []
sklansky f [x] = [x]
sklansky f xs = left' ++ [ f (last left') r | r - right' ]
where
(left, right) = splitAt (length xs `div` 2) xs
left' = sklansky f
On Feb 17, 2008, at 18:53 , Chad Scherrer wrote:
ByteStrings have given a real performance boost to a lot of Haskell
applications, and I'm curious why some of the techniques aren't more
abstracted and widely available. If it's because it's a big job,
that's certainly understandable, but maybe
In C and in Java, I can use truetype fonts in Haskell using select
libraries, and I'd like to be able to do the same in Haskell. Are
there any portable libraries out there for loading fonts into OpenGL
geometry for Haskell? I can use the vector fonts from GLUT is
absolutely neccessary, but I'd
ByteStrings have given a real performance boost to a lot of Haskell
applications, and I'm curious why some of the techniques aren't more
abstracted and widely available. If it's because it's a big job,
that's certainly understandable, but maybe there's something I'm
overlooking that some of the
On Feb 17, 2008, at 19:13 , Jefferson Heard wrote:
In C and in Java, I can use truetype fonts in Haskell using select
libraries, and I'd like to be able to do the same in Haskell. Are
there any portable libraries out there for loading fonts into OpenGL
geometry for Haskell? I can use the
Hi Alan
I can help but feeling curious. Did some of the answers actually help
you? Are you still as doubtful about Haskell as when you wrote your
email?
Greetings,
Mads Lindstrøm
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On Feb 17, 2008 4:13 PM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
Have you looked at the stream-fusion package on Hackage?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/stream-
fusion-0.1.1
Yeah, I've seen this. It's nice that this is separated, but a little
unsatisfying
On Feb 17, 2008, at 19:23 , Chad Scherrer wrote:
On Feb 17, 2008 4:13 PM, Brandon S. Allbery KF8NH
[EMAIL PROTECTED] wrote:
Have you looked at the stream-fusion package on Hackage?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/stream-
fusion-0.1.1
Yeah, I've seen this. It's
chad.scherrer:
ByteStrings have given a real performance boost to a lot of Haskell
applications, and I'm curious why some of the techniques aren't more
abstracted and widely available. If it's because it's a big job,
that's certainly understandable, but maybe there's something I'm
overlooking
On Sat, Feb 16, 2008 at 05:04:53PM -0800, Donn Cave wrote:
But in Haskell, you cannot read a file line by line without writing an
exception handler, because end of file is an exception! as if a file does
not normally have an end where the authors of these library functions
came from?
Part of
chad.scherrer:
On Feb 17, 2008 4:13 PM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
Have you looked at the stream-fusion package on Hackage?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/stream-
fusion-0.1.1
Yeah, I've seen this. It's nice that this is separated, but
On Feb 18, 2008 12:20 AM, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
On Feb 17, 2008, at 19:13 , Jefferson Heard wrote:
In C and in Java, I can use truetype fonts in Haskell using select
libraries, and I'd like to be able to do the same in Haskell. Are
there any portable libraries
they currently use two different fusion systems. bytestring uses an
older version of what is now stream fusion. at some point we'll switch
bytestrings over to using the new stuff in the stream-fusion package,
since its a lot better.
Oh, that's pretty interesting. I had assumed bytestring had
chad.scherrer:
they currently use two different fusion systems. bytestring uses an
older version of what is now stream fusion. at some point we'll switch
bytestrings over to using the new stuff in the stream-fusion package,
since its a lot better.
Oh, that's pretty interesting. I had
Thanks. that's certainly a thought... doesn't make the text 3d,
though, does it? I'd ideally like to have something that turns the
text into geometry, but this'll do in a pinch...
On Sun, Feb 17, 2008 at 8:26 PM, Luke Palmer [EMAIL PROTECTED] wrote:
On Feb 18, 2008 12:20 AM, Brandon S.
On Feb 17, 2008 5:01 PM, Don Stewart [EMAIL PROTECTED] wrote:
yeah, with lists, as compared to bytestrings, there are:
* more complex operations to fuse
* allocation is much cheaper (lazy list cons nodes)
* built in desugaring for build/foldr fusion interferes (enumerations,
On Sun, 2008-02-17 at 18:02 -0800, Chad Scherrer wrote:
On Feb 17, 2008 5:01 PM, Don Stewart [EMAIL PROTECTED] wrote:
yeah, with lists, as compared to bytestrings, there are:
* more complex operations to fuse
* allocation is much cheaper (lazy list cons nodes)
* built in
At Mon, 18 Feb 2008 01:26:17 +,
Luke Palmer wrote:
I have an immature, but precise and picky implementation that renders text in
a ttf font to an OpenGL texture (using SDL-ttf) here:
http://svn.luqui.org/svn/misc/luke/work/code/haskell/frp/Fregl/Draw.hs
(It may have some dependencies in
Are there generally accepted English language names for the arrow combinators?
compose?
pair?
etc...
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On Mon, 2008-02-18 at 03:37 +, Tom Davies wrote:
Are there generally accepted English language names for the arrow combinators?
compose?
That's fine though ambiguous.
pair?
etc...
The rest don't generally accepted readings. There are some examples of
wordier names used (e.g. fork
A while ago I wrote a little data structure that allows weighted
random selection-without-replacement from a collection of values in
O(log n) time.[1] I'm now in the process of packaging it up for
Hackage, but I'm looking for good names for both the type and its
operations.
The name I have at the
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