#2275: Poor indication of type error location
+---
Reporter: guest| Owner:
Type: bug | Status: new
Priority: normal | Component:
#2275: Poor indication of type error location
+---
Reporter: guest|Owner:
Type: bug | Status: new
Priority: normal |
#2275: Poor indication of type error location
-+--
Reporter: guest| Owner:
Type: bug | Status: new
Priority: normal |
#2269: Word type to Double or Float conversions are slower than Int conversions
+---
Reporter: dons| Owner: [EMAIL PROTECTED]
Type: feature request | Status: new
#1958: collect2: ld terminated with signal 10 [Bus error]: Building parsec on a
PPC Mac OS X 10.5 Leopard as part of GHC 6.9
-+--
Reporter: thorkilnaur | Owner: thorkilnaur
Type: bug |
#2277: GHCi silently aborts on 'take' computation
---+
Reporter: cdsmith | Owner:
Type: bug | Status: new
Priority: normal | Component: GHCi
Dear Haskellers,
It is not yet too late to contribute to the 14th edition of the HCA
Report. The deadline is this weekend,
Saturday, 10 May 2008.
If you haven't already, please write an entry for your new project or
update your old entry.
Please mail your entries to hcar at haskell dot org
You can also drop the type signature and see what type deduction you get in
ghci :)
Your program would have compiled well without the type signature!
It's also a good exercise to come up with the most general type of a
function that you write, and then compare it with the type that is deduced
by
I'm pleased to announce the 0.1 release of Streaming Component
Combinators in Haskell, based on my earlier work done in OmniMark and
published in paper
Mario Blažević, Streaming component combinators, Extreme Markup
Languages, 2006.
Hello,
I am running some monadic code that I have written. I double checked my
code and it seems to be ok (no guarantee though). I am getting a resource
exhausted (Message too long). I just did a google on resource exhausted
and saw a few posts on the number of open files which is obviously
On 08/mag/08, at 08:59, Benjamin L. Russell wrote:
One hint that is not (at least to my knowledge) listed on
haskell.org is that, according to at least one user (see The
Programmers’ Stone » Blog Archive » A First Haskell Experience at
Hi Donnie,
Any chance of those issues being moved over still? I'd prefer to
read the older issues in pdf format, like the new issues.
I have gotten permission from (almost) all the authors to move the
content to the new wiki. I've started reformatting everything to the
MediaWiki format
More importantly I grepped(Linux) through the ghc6.8.2 source for resource
exhausted .. maybe incorrectly ??
Vasili
On Fri, May 9, 2008 at 1:04 AM, Galchin, Vasili [EMAIL PROTECTED] wrote:
Hello,
I am running some monadic code that I have written. I double checked my
code and it seems
Dear Haskellers,
It is not yet too late to contribute to the 14th edition of the HCA
Report. The deadline is this weekend,
Saturday, 10 May 2008.
If you haven't already, please write an entry for your new project or
update your old entry.
Please mail your entries to hcar at haskell dot org
Hello Giorgio,
Friday, May 9, 2008, 10:40:47 AM, you wrote:
be the next one. Should I wait for Real world Haskell or do you think
that the books you listed offer something new/different/more advanced
than Programming in Haskell?
i recommend you to read papers from the
David Waern wrote:
2008/5/8 Simon Marlow [EMAIL PROTECTED]:
So basically you want to run a lexer over the source again to collect all
the comments?
Yes.
You really want to use GHC's lexer, because otherwise you
have to write another lexer.
I don't mind writing a lexer that just collects
Hi,
No, the thunks are (usually) stored on the heap. You don't get the
stack overflow until you actually force the computation at which point
you have an expression like:
(...(((1+2)+3)+4) ... + 1000)
which requires stack in proportion to the number of nested parentheses
(effectively)
Edsko de Vries [EMAIL PROTECTED] wrote:
(...(((1+2)+3)+4) ... + 1000)
which requires stack in proportion to the number of nested parentheses
Ah, that makes! So does it make sense to talk about tail recursive
thunks? Or does the evaluation of thunks always take stack space
2008/5/9 Simon Marlow [EMAIL PROTECTED]:
David Waern wrote:
2008/5/8 Simon Marlow [EMAIL PROTECTED]:
So basically you want to run a lexer over the source again to collect all
the comments?
Yes.
You really want to use GHC's lexer, because otherwise you
have to write another lexer.
I
Paul: okay, da capo: We prove/test through case analysis
that the predicate p holds true for the first/starting case/element
in the sequence. When dealing with natural numbers this could be 0 or
1. We try the formula with 0 and if it returns the desired result we
move onto the next
--- On Fri, 5/9/08, Bulat Ziganshin [EMAIL PROTECTED] wrote:
Hello Giorgio,
Friday, May 9, 2008, 10:40:47 AM, you wrote:
be the next one. Should I wait for Real world Haskell
or do you think
that the books you listed offer something
new/different/more advanced
than Programming in
On 2008 May 9, at 2:51, Wouter Swierstra wrote:
Any chance of those issues being moved over still? I'd prefer to
read the older issues in pdf format, like the new issues.
I have gotten permission from (almost) all the authors to move the
content to the new wiki. I've started reformatting
On 2008 May 9, at 2:04, Galchin, Vasili wrote:
I am running some monadic code that I have written. I double
checked my code and it seems to be ok (no guarantee though). I am
getting a resource exhausted (Message too long). I just did a
google on resource exhausted and saw a few posts
Am Freitag, 9. Mai 2008 13:50 schrieb PR Stanley:
Paul: okay, da capo: We prove/test through case analysis
that the predicate p holds true for the first/starting case/element
in the sequence. When dealing with natural numbers this could be 0 or
1. We try the formula with 0 and if it
Hi all,
I'm trying to make RFC calls to SAP using the nwsaprfc library. Some structs
defined in the library contains arrays (byte or word arrays). For example:
typedef struct _RFC_ATTRIBUTES
{
SAP_UC dest[64+1]; /* RFC destination */
SAP_UC host[100+1];
On 2008 May 9, at 9:42, Olivier Boudry wrote:
Of course it won't work as HArrayStruct in file HArrayStruct.hs uses
Strings and String is not an instance of Storable.
Ideally I would need some sort of Storable array of char. Is
Data.Storable.Array the type I'm looking for? Could someone
Darrin Thompson wrote:
2008/5/8 Donnie Jones [EMAIL PROTECTED]:
I would be interested to see an article on Haskell in the same light as this
Ocaml article, aka a constructive criticism of Haskell.
http://www.drmaciver.com/2008/02/tell-us-why-your-language-sucks/
Impressive. He
Hello all,
In the GHC Commentary [1] I can read that the type checker adds type
information to the syntax tree. So I would expect that there is a way to
get a syntax tree of type HsModule Id.
The GHC API provides functions checkModule and checkAndLoadModule which
both return a CheckedModule that
The function (++) :: [x] - [x] - [x] has O(n) complexity.
If somebody were to invent some type that looks like [x] but actually
uses some sort of tree rather than a linked list, you should be able to
get O(1) concatenation. Has anybody ever implemented such a thing?
Hi
data List a = Zero | One a | Two (List a) (List a)
On Fri, May 9, 2008 at 3:16 PM, Andrew Coppin
[EMAIL PROTECTED] wrote:
The function (++) :: [x] - [x] - [x] has O(n) complexity.
(++) = Two -- O(1) complexity
If somebody were to invent some type that looks like [x] but actually uses
Hey everyone,
I was tired of all those graphical Twitter clients that aren't usable
from my Terminal, so I wrote my own. It's still very much alpha, but
comments or improvements are more than welcome. You can install it by
downloading the twitter-package from hackage.
In order to get it
Hello,
The function (++) :: [x] - [x] - [x] has O(n) complexity.
If somebody were to invent some type that looks like [x] but actually
uses some sort of tree rather than a linked list, you should be able to
get O(1) concatenation. Has anybody ever implemented such a thing?
You can also
Hi Brandon,
Thanks for your help, CString will work great for Char arrays, but what
about the 16bit-Word arrays? I was not clear in my previous post but the
structures used in the nwrfcsdk library can use 8bit or 16 bit chars
depending on a #define (#define SAPwithUNICODE).
Reading another post
Andrew Coppin wrote:
The function (++) :: [x] - [x] - [x] has O(n) complexity.
If somebody were to invent some type that looks like [x] but actually
uses some sort of tree rather than a linked list, you should be able to
get O(1) concatenation. Has anybody ever implemented such a thing?
Hello Olivier,
Friday, May 9, 2008, 6:28:38 PM, you wrote:
Thanks for your help, CString will work great for Char arrays, but
what about the 16bit-Word arrays?
TString. they are used a lot for interfacing with Win32 API
--
Best regards,
Bulatmailto:[EMAIL
Put them up as is, let people with haskellwiki accounts reformat them?
Good idea. All the old content is now available, although some
articles do look fairly horrendous:
http://www.haskell.org/haskellwiki/The_Monad.Reader/Issue2
http://www.haskell.org/haskellwiki/The_Monad.Reader/Issue3
I'm pleased to announce the 0.1 release of Streaming Component
Combinators in Haskell, based on my earlier work done in OmniMark and
published in paper
Mario Blažević, Streaming component combinators, Extreme Markup
Languages, 2006.
On Fri, May 9, 2008 at 10:02 AM, Andrew Coppin [EMAIL PROTECTED]
wrote:
Darrin Thompson wrote:
2008/5/8 Donnie Jones [EMAIL PROTECTED]:
I would be interested to see an article on Haskell in the same light as
this
Ocaml article, aka a constructive criticism of Haskell.
On Fri, May 09, 2008 at 11:35:32AM -0400, Brent Yorgey wrote:
On Fri, May 9, 2008 at 10:02 AM, Andrew Coppin [EMAIL PROTECTED]
wrote:
While I'm here - I'm aware of how you control importing [or not] from the
Prelude. Is there a way that I can, for example, import all the stuff like
the
Brent Yorgey wrote:
On Fri, May 9, 2008 at 10:02 AM, Andrew Coppin
[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] wrote:
While I'm here - I'm aware of how you control importing [or not]
from the Prelude. Is there a way that I can, for example, import
all the stuff like the basic
On Fri, May 09, 2008 at 05:19:05PM +0100, Andrew Coppin wrote:
Brent Yorgey wrote:
On Fri, May 9, 2008 at 10:02 AM, Andrew Coppin
[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] wrote:
While I'm here - I'm aware of how you control importing [or not]
from the Prelude. Is there a way
David Roundy wrote:
It's pretty easy (albeit tedious) to do this for yourself (except that you
wouldn't automatically turn off the import of Prelude, and you'd still
suffer from the instances disease).
module Prelude.Types ( Int, Double, Char, String ) where
import Prelude
Sounds like a
Hi
(take 4 . map (0)) (f s t)
where
s = 2 : t
t = 3 : s
f = zipWith (-)
What would be the order of evaluation for the above code? How would I
illustrate the evaluation step-by-step?
I'm guessing that the code necessitates lazy evaluation and as such
it starts with take then
On 9 May 2008, at 21:52, PR Stanley wrote:
Hi
(take 4 . map (0)) (f s t)
where
s = 2 : t
t = 3 : s
f = zipWith (-)
What would be the order of evaluation for the above code? How would
I illustrate the evaluation step-by-step?
What do you need it for, really? Pure functional
Hello,
I'm quite new to Haskell, but this is my understanding... Please correct me
if I am wrong, as there is a good chance I am. ;)
### Begin Code ###
module Main where
main =
putStrLn (show( (take 4 . map ( 0)) (f s t) ))
where
s = 2 : t
t = 3 : s
f = zipWith (-)
{-
-
PR Stanley wrote:
(take 4 . map (0)) (f s t)
where
s = 2 : t
t = 3 : s
f = zipWith (-)
What would be the order of evaluation for the above code?
As I understand it Haskell does not specify an order of evaluation
and it would therefore be a mistake to write a program which relies
on
As I understand it Haskell does not specify an order of evaluation
and it would therefore be a mistake to write a program which relies
on a particular evaluation order. This is the 'unsafe' aspect of
unsafePerformIO.
Hmm... IMHO unsafePerformIO is 'unsafe' because it can lead to type
errors
On 5/9/08, Daniel Fischer [EMAIL PROTECTED] wrote:
Right. I only wanted to say that we might have chosen the wrong base case for
the proposition. If p(0) doesn't hold, then obviously [for all n. p(n)]
doesn't hold. But [for all n. p(n) implies p(n+1)] could still be true, and
in that case, if
On 2008.05.09 16:23:03 +0200, Chris Eidhof [EMAIL PROTECTED] scribbled 0.6K
characters:
Hey everyone,
I was tired of all those graphical Twitter clients that aren't usable from
my Terminal, so I wrote my own. It's still very much alpha, but comments or
improvements are more than welcome. You
OK, so I feel I understand monads fine. I regularly use Maybe, [] and
IO, and I've even constructed a few monads of my own. But here's a
question: what is the purpose of the MonadPlus class?
Clearly it defines a binary operation over monadic values and an
identity element for that operation.
On Fri, May 09, 2008 at 08:39:38PM +0100, Andrew Coppin wrote:
OK, so I feel I understand monads fine. I regularly use Maybe, [] and
IO, and I've even constructed a few monads of my own. But here's a
question: what is the purpose of the MonadPlus class?
Clearly it defines a binary
On Fri, May 9, 2008 at 2:39 PM, Andrew Coppin [EMAIL PROTECTED]
wrote:
[In a somewhat unrelated question... I saw some code the other day that
used Either as if it were a monad. And yet, I don't see an instance given in
the standard libraries - even though there should be one. I can see
Andrew Coppin wrote:
But here's a
question: what is the purpose of the MonadPlus class?
It gives you a way of working with monads as monoids. Consider a Parsec
example:
metasyntactic = text foo `mplus` text bar `mplus` text baz
You'll get back whichever one matched, in left-to-right-order,
Bryan O'Sullivan wrote:
Andrew Coppin wrote:
But here's a
question: what is the purpose of the MonadPlus class?
It gives you a way of working with monads as monoids. Consider a Parsec
example:
metasyntactic = text foo `mplus` text bar `mplus` text baz
You'll get back whichever one
On May 9, 2008, at 15:56 , Andrew Coppin wrote:
Bryan O'Sullivan wrote:
Andrew Coppin wrote:
But here's a
question: what is the purpose of the MonadPlus class?
It gives you a way of working with monads as monoids. Consider a
Parsec
example:
metasyntactic = text foo `mplus` text bar
On Fri, 2008-05-09 at 12:47 -0700, David Roundy wrote:
On Fri, May 09, 2008 at 08:39:38PM +0100, Andrew Coppin wrote:
OK, so I feel I understand monads fine. I regularly use Maybe, [] and
IO, and I've even constructed a few monads of my own. But here's a
question: what is the purpose of
Andrew Coppin wrote:
...so it's a kind of choice operator? Run all actions until you get to
one that succeeds and return the result from that?
In the context of Parsec, yes. In the grander scheme of things, the
behaviour depends on whatever is appropriate for the particular monad
you're
On Fri, 2008-05-09 at 12:48 -0700, Bryan O'Sullivan wrote:
Andrew Coppin wrote:
But here's a
question: what is the purpose of the MonadPlus class?
It gives you a way of working with monads as monoids.
I find this description mostly useless. Monads form monoids without
being MonadPlus.
It sounds like the semantics of the MonadPlus methods are
under-specified. I recall once writing a newtype wrapper to treat the
same non-determinism monad with different mplus semantics, akin to cut
versus backtracking.
I think of MonadPlus as a less expressive version of msplit, from
Hi
(take 4 . map (0)) (f s t)
where
s = 2 : t
t = 3 : s
f = zipWith (-)
What would be the order of evaluation for the above code? How would
I illustrate the evaluation step-by-step?
What do you need it for, really? Pure functional programs are not
about evaluation order, but
I'm experiencing strange behavior when executing some Haskell OpenGL
code inside unsafeInterleaveIO.
For example,
vp - get GL.viewport
returns garbage, as if the opengl context is not correctly set.
Is this to be expected? Or is it likely a bug on my side?
Thanks,
Peter
Andrew asked,
...so it's a kind of choice operator? Run all actions until you get to one
that succeeds and return the result from that?
The eternal bit of trickiness for Haskell is that type classes group
often together things that people don't immediately see as similar -
monads probably
As long as you don't mind producing two-color images,
http://haskell.org/haskellwiki/Library/PNG is an option. I found it
very easy to extend it to eight-bit grayscale - I didn't need
fullcolor images.
/g
On Sat, May 3, 2008 at 11:12 PM, Nahuel Rullo [EMAIL PROTECTED] wrote:
Hi list, i am new
On 10 May 2008, at 00:43, Dan Piponi wrote:
Andrew asked,
...so it's a kind of choice operator? Run all actions until you get
to one
that succeeds and return the result from that?
The eternal bit of trickiness for Haskell is that type classes group
often together things that people don't
On Fri, 9 May 2008, Peter Verswyvelen wrote:
I'm experiencing strange behavior when executing some Haskell OpenGL code
inside unsafeInterleaveIO.
For example,
vp - get GL.viewport
returns garbage, as if the opengl context is not correctly set.
Sounds reasonable.
Hello,
One frequent criticism of Haskell (and by extension GHC) is that it has
unpredictable performance and memory consumption. I personally do not find
this to be the case. I suspect that most programmer confusion is rooted in
shaky knowledge of lazy evaluation; and I have been able to fix,
Hi
I thought [1, 2, 3] :: [Int]
GHC says it's (Num t) [t]
Okay, when it comes to 3.3:[1,2,3] (Num t) = [t] makes more sense.
Is that the only reason?
Cheers,
Paul
___
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Haskell-Cafe@haskell.org
On Mon, Nov 26, 2007 at 9:27 AM, Wouter Swierstra [EMAIL PROTECTED] wrote:
On 18 Aug 2007, at 20:10, Henk-Jan van Tuyl wrote:
Now that all hawiki pages have been removed, we have lost some valuable
information. For example The Monad.Reader; on
Hello PR,
Saturday, May 10, 2008, 1:07:48 AM, you wrote:
Okay, when it comes to 3.3:[1,2,3] (Num t) = [t] makes more sense.
Is that the only reason?
the reason is that 1 as any other numerical constant, may be directly
used as Int, Integer, Double or any other Num value. if 1 is Int, you
will
On Fri, 9 May 2008, Andrew Coppin wrote:
Brent Yorgey wrote:
On Fri, May 9, 2008 at 10:02 AM, Andrew Coppin [EMAIL PROTECTED]
mailto:[EMAIL PROTECTED] wrote:
While I'm here - I'm aware of how you control importing [or not]
from the Prelude. Is there a way that I can, for example,
jeff.polakow:
Hello,
One frequent criticism of Haskell (and by extension GHC) is that it has
unpredictable performance and memory consumption. I personally do not find
this to be the case. I suspect that most programmer confusion is rooted in
shaky knowledge of lazy
Miguel said:
Well, that's the whole point of mathematics, isn't it?
Abstraction is common to mathematics and computing. But in computing
the abstraction often follows lines that seem obvious. For example a
GUI library might have a Widget class and people can immediately
identify various regions
Miguel Mitrofanov [EMAIL PROTECTED] wrote:
As I understand it Haskell does not specify an order of evaluation
and it would therefore be a mistake to write a program which relies
on a particular evaluation order. This is the 'unsafe' aspect of
unsafePerformIO.
Hmm... IMHO
On Fri, May 09, 2008 at 02:24:12PM -0700, Don Stewart wrote:
jeff.polakow:
Hello,
One frequent criticism of Haskell (and by extension GHC) is that it has
unpredictable performance and memory consumption. I personally do not find
this to be the case. I suspect that most programmer
Oh, you sure?
quote src=http://www.haskell.org/ghc/docs/latest/html/libraries/base/System-IO-Unsafe.html
It is less well known that unsafePerformIO is not type safe. For
example:
test :: IORef [a]
test = unsafePerformIO $ newIORef []
main = do
writeIORef test
Hello,
I am trying to write FFI wrappers for a dynamic library in windows.
I would like to get some help in how to go about doing things.
For example for this C function, the import and wrapper I came up with
are listed below.
-- STATUS LNPUBLIC NSFDbOpen (char far *PathName, DBHANDLE far
Miguel Mitrofanov [EMAIL PROTECTED] wrote:
Oh, you sure?
I was, until you wrote that. But then, I am, as I wouldn't use
unsafePerformIO together with IORef's, it's giving me the creeps.
--
(c) this sig last receiving data processing entity. Inspect headers for
past copyright information. All
On 2008 May 9, at 17:07, PR Stanley wrote:
I thought [1, 2, 3] :: [Int]
GHC says it's (Num t) [t]
Okay, when it comes to 3.3:[1,2,3] (Num t) = [t] makes more sense.
Is that the only reason?
The Haskell 98 standard says that numeric literals are of type Num t
= t (so you don't need to
GHC already ignores the existence of seq, for instance when doing list
fusion.
The unconstrained seq function just ruins too many things.
I say, move seq top a type class (where is used to be), and add an unsafeSeq
for people who want to play dangerously.
-- Lennart
On Tue, May 6, 2008 at 3:27
Ah, I didn't think about the GHC options that change the lexical
syntax. You're right, using the GHC lexer should be easier.
and, if you do that, you could also make the GHC lexer
squirrel away the comments (including pragmas, if they aren't
already in the AST) someplace safe, indexed by, or
Hi
data Ord a = Tree a = Nil | Node (Tree a) a (Tree a)
How would one go about inserting a value in a binary search tree of
the above description?
Cheers
Paul
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Haskell-Cafe@haskell.org
On 10 May 2008, at 00:35, PR Stanley wrote:
Hi
data Ord a = Tree a = Nil | Node (Tree a) a (Tree a)
How would one go about inserting a value in a binary search tree of
the above description?
All you need to do is consider what the trees should look like in the
two cases:
If I try and
Are there any invariants you wish to maintain when inserting? If not, it's
rather trivial.
-- Lennart
On Fri, May 9, 2008 at 11:35 PM, PR Stanley [EMAIL PROTECTED] wrote:
Hi
data Ord a = Tree a = Nil | Node (Tree a) a (Tree a)
How would one go about inserting a value in a binary search
PR Stanley [EMAIL PROTECTED] wrote:
Hi
data Ord a = Tree a = Nil | Node (Tree a) a (Tree a)
How would one go about inserting a value in a binary search tree of
the above description?
Using a library ;)
Inserting isn't the problem, balancing is where things get interesting:
have a look at
Actually, you've touched an important point there. It's balancing
that I'm having difficulty with.
Paul
At 23:46 09/05/2008, you wrote:
PR Stanley [EMAIL PROTECTED] wrote:
Hi
data Ord a = Tree a = Nil | Node (Tree a) a (Tree a)
How would one go about inserting a value in a binary search
Hello PR,
Saturday, May 10, 2008, 3:10:59 AM, you wrote:
in C you'd fiddle with pointers and Bob's your uncle. Here I'm not
sure how to piece that tree back together again with the new element
after having expanded it recursively.
in Haskell, you just return new tree with element inserted.
Lennart Augustsson wrote:
Even so, it's instructive to study how the normal order reduction of
this expression would proceed under the assumption that all 4 elements
will be used.
I think it's useful to try normal order until weak head normal form.
Not all steps are shown. Definitions of
website:http://roguestar.downstairspeople.org
darcs 2:darcs get --lazy http://www.downstairspeople.org/darcs/roguestar
tarball:http://www.downstairspeople.org/roguestar/roguestar-0.2.tar.gz
After much delay, I'm happy to announce Roguestar 0.2.
Roguestar is a science
Hello,
I changed the version # in a cabal file and now I get ...
runhaskell Setup.hs configure
Configuring unix-2.4.0.0...
[EMAIL PROTECTED]:~/FTP/Haskell/unix-2.2.0.0$ runhaskell Setup.hs build
Setup.hs: unix.cabal has been changed, please re-configure.
Now no matter what I change the
So here I am with 64 bit Athlon hardware, running amd64
NetBSD (a.k.a. x86_64), reasonably motivated to compile
Haskell. From what I make of the porting instructions,
my only hope is to install FreeBSD-amd64 on another
partition and download the 6.6.1 ghc for that platform,
use it to generate .hc
Hello,
Additional POSIX realtime (POSIX 1003.1b) support has been added:
1) MQueue.hsc - POSIX message queues
Supported FFI bindings for:
- mq_open
- mq_close
- mq_unlink
- mq_getattributes
- mq_setattributes
- mq_send
vigalchin:
Hello,
Additional POSIX realtime (POSIX 1003.1b) support has been added:
1) MQueue.hsc - POSIX message queues
Supported FFI bindings for:
- mq_open
- mq_close
- mq_unlink
-
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