frode k writes:
> Installation of GHC 7.0.2 failed:
> # ./configure --prefix=/usr/haskell-platform-2011.2.0.0/
> checking for path to top of build tree...
> utils/ghc-pwd/dist/build/tmp/ghc-pwd: /lib64/libc.so.6: version `GLIBC_2.9'
> not found (required by utils/ghc-pwd/dist/build/tmp/ghc-pwd)
>
Tristan Ravitch writes:
> The ghc7 binaries are compiled against a newer version of glibc than
> is available on RHEL/CentOS. It works fine if you compile ghc7 from
> source yourself (you can use 6.12 for that).
Did it? I tried to do that, but I got errors about needing -fPIC. I
tried to mess
frode k writes:
> (Note: I also installed GCC 4.4 (as mentioned by Mr Peterson) before I
> retried installing Cabal and the Haskell Platform , but I do not think that
> affected the build / compile process at all, since GHC and not GCC is used
> here. And GCC 4.4 is also installed next to 4.1 tha
frode k writes:
> The command should be "-with-gcc".
Ah, thanks, missed that, I guess.
> Implicit import declaration:
> Could not find module `Prelude':
> Perhaps you haven't installed the profiling libraries for package
> `base'?
> Use -v to see a list of the files searched for
Hi,
I'm seeing some weirdness here. My code does this:
omap <- atomically $ (newArray_ (0,n-1) :: STM (TArray Int Int))
This gives a stack overflow when n is one million. The equivalent code
in the ST monad doesn't show this behavior, and works as expected.
I'm not sure what is going on
Bas van Dijk writes:
Thanks to you and Felipe for trying this out.
>> omap <- atomically $ (newArray_ (0,n-1) :: STM (TArray Int Int))
> I can't reproduce this with ghci-7.0.2 (base-4.3.1.0, array-0.3.0.2
> and stm-2.2.0.1).
It works (calling the same function) from GHCi, but breaks when
comp
Bas van Dijk writes:
> sequence ms = foldr k (return []) ms
> where
> k m m' = do
> x <- m
> xs <- m'
> return (x:xs)
Isn't this really a strictness problem with the STM monad? If I
understand correctly, this forces xs before x can be examined. Something
to be
Bas van Dijk writes:
> Maybe it's not really a bug:
Any idea why it works in GHCI?
-k
--
If I haven't seen further, it is by standing in the footprints of giants
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/l
"Vasili I. Galchin" writes:
> I am very curious about the readiness of trading and banking industries
> to adopt FPLs like Haskell:
Yes, I've noticed that, too. And it goes both ways - it's an industry
of which the computer science crowd tends to be unaware as well.
Some hypotheses, off t
John Millikin writes:
> OSX's chief weirdness is that its GUI programs swap ':' and '/' when
> displaying filenames.
A remnant from the bad old days of MacOS <10, where : was the path
separator, and / was a perfectly good character to use in filenames.
> -- | Try to decode a FilePath to Text,
Michael Snoyman writes:
> My guess is that a large subset of Haskell modules start with one of left
> brace (starting with comment or language pragma), m (for starting with
> module), or some whitespace character. So it *might* be feasible to take a
> guess at things. But as I said before: I like
Evan Laforge writes:
>> Most of the (non-IO) runtime errors I get using Haskell software is
>> due to head or fromJust, it's actually quite annoying.
> Just singling this one out because I've heard it before. I've never
> gotten a runtime error from these. It seems quite easy to just not
> us
"Edward Z. Yang" writes:
> I've been toying around with some ideas where we do alternative
> forms of controlled mutation. One such idea has to do with memoization.
[..]
> Hash tables take advantage of this fact by simply chaining together values
> in a linked list if they land in the same buc
Henning Thielemann writes:
> I like to apply for the quote of the week. :-)
>
> "If Haskell is great because of its laziness,
>then Python must be even greater,
>since it is lazy at the type level."
Well, this is indeed (an elegant reformulation of) a common objection,
namely that Pyth
I'm following Harper's blog, Existential Type¹, which I find to be an
enjoyable and entertainingly written tirade about the advantages of
teaching functional programming - specifically ML - to students. Of
course, he tends to be critical of Haskell, but it's nice to get some
thought provoking opi
Hi,
I'm using Bryan's bloomfilter package, and I would like to calculate the
false positive rate after constructing the bloom filter. Two reasons:
1. Bloom filters have a power-of-two size, which means that the FP rate
you ask for becomes an approximation (upper bound), and the real FP rate
mig
Daniel Fischer writes:
> Not having Eq and Ord instances for Double and Float would be extremely
> inconvenient (too inconvenient to seriously consider, I think), so one can
> a) do what's done now
> b) make NaNs an error
> c) come up with a brilliant solution.
Maybe not terribly brilliant, but
Casey McCann writes:
> It would improve things in the sense of giving well-behaved instances
> for Eq and Ord, yes. It would not improve things in the sense that it
> would violate the IEEE floating point spec.
I'm not intimately familiar with IEEE 754, but in any case we'd be in
good company: R
Casey McCann writes:
>> At any rate, I think we already violate the spec by not having the
>> required "unordered" result for comparisons, and just treating every
>> comparison involving a NaN as "GT". I don't think considering NaN as
>> e.g. less than -Inf would violate the spec *more*.
>
> Wel
Andrew Coppin writes:
> I'm trying to voice the opinion that there is such a thing as too many
> libraries. The article I linked to explains part of why this is the
> case, in a better way than I've been able to phrase it myself.
I don't think so, the article seems to talk more about social prob
Juan Daugherty writes:
> Every computing culture is different.
Definitely. I've just given up on several "cultures" which are just too
vitriolic. Scala is on my list of interesting stuff to look at some
day, but if I'm going to be flamed for asking questions about the
language, I can easily fi
"Richard O'Keefe" writes:
>> Then tell me, why does calculating the length of a (Haskell)
>> list has O(n) complexity.
> Because it is a rather rare operation and the cost of doing
> this would be far higher than you think.
I suspect that if you store the length non-strictly, it would build up
Tom Murphy writes:
Modules tend to group togheter data structures and functions that
operate on them - i.e. natural units of code. So I think modules are
good also for didactical reasons, in that module imports limit the scope
a reader needs to know to understand the code.
I don't know Erlang,
Aleksandar Dimitrov writes:
> Now, here's some observations: on a 75M input file (minuscule, compared to
> what
> I actually need) this program will eat 30M of heap space (says profiling) and
> return in 14 secs.
>
> I have two problems with that: a) that's too much heap space, b) the actual
>
Since frequency counts are an important use of map-like data structures,
I did a brief test of the available options. First using regular
strings for input, and Data.Map.fromListWith - i.e. the operational bit being:
freqs :: [String] -> M.Map String Int
freqs = M.fromListWith (+) . map (,1)
By the way, what is the advantage of using iteratees here? For my
testing, I just used:
main = printit . freqs . B.words =<< B.readFile "words"
(where 'printit' writes some data to stdout just to make sure stuff is
evaluated, and you've already seen some 'freqs' examples)
I have a bunch of o
dm-list-haskell-c...@scs.stanford.edu writes:
> leaking file descriptors
...until they are garbage collected. I tend to consider the OS fd
limitation an OS design error - I've no idea why there should be some
arbitrary limit on open files, as long as there is plenty of memory
around to store the
Michael Litchard writes:
> I disagree. I'm by no means proficient in Haskell. And, I never
> bothered learning PHP. I will when I need to. PHP programmers are a
> dime a dozen.
..and since PHP programmers are a dime a dozen, any decent manager (who,
after all, has an MBA and knows that employee
Guy writes:
> Out of interest, is there any other language where the comment
> delimiter is invalid if immediately followed by a symbol?
Perl has a rather infamous example where the comment syntax may depend
on run-time properties - would that count?
whatever / 25 ; # / ; die "this dies!";
Guy writes:
> Out of interest, is there any other language where the comment
> delimiter is invalid if immediately followed by a symbol?
Another quaint example, in shell scripts, lines starting with '#' are
comments, except when the first line starts with '#!'. Admittedly, this
is still a comm
Ivan Lazar Miljenovic writes:
> And #! in the first line is also treated as a comment in Haskell code
> so that you can run it as a script.
True. But then you're allowed to add arbitrary symbols after it, I
think. At least, GHC seems happy about it.
-k
--
If I haven't seen further, it is by
"Dmitri O.Kondratiev" writes:
>>xss2 <- read `fmap` readFile "output.txt"
> Two questions:
> 1) Why to use 'fmap' at all if a complete file is read in a single line of
> text?
Because it's not 'map', it's more generalized. So the argument ('read'
here) is applied to whatever is "inside" th
"Dmitri O.Kondratiev" writes:
> Which platform - Mac OS X, Linux or Win32 is best for development with GHC
> today?
I think most developers use Linux, which tends to ensure that more stuff
will work there. Most developers will also tend to use recent versions
of everything, so go with Fedora or
"Dmitri O.Kondratiev" writes:
>> Let me know if you would like opinions on Emacs vs vi!
>
> I know vi, but it is just that I got used to Emacs which is my main IDE for
> most PL that I work with and for many years already )
No, no! Stop, it was just a joke, really. I regret it already. :-)
-k
"John D. Ramsdell" writes:
> Developers should be using older versions of GHC because they cannot
> be sure users will have an up-to-date GHC.
I wonder, how hard would it be to have, say Amazon images of various
Linux distributions with ghc and cabal-install available? Currently, I
have a dis
Eugene Kirpichov writes:
> 2011/7/1 Heinrich Apfelmus :
>> Eugene Kirpichov wrote:
>>> I'm rewriting timeplot to avoid holding the whole input in memory, and
>>> naturally a problem arises:
>> Plain old lazy lists?
Heretic! :-)
I generally have written a bunch of programs that do things that
[snip haskell@, leaving -café]
Heinrich Apfelmus writes:
> Do you know any *small GUI programs* that you would *like* to see
> *implemented with Functional Reactive Programming?*
I don't know if this fits the bill, but a tool that I'd like to see is
plotting for one or more live streams of dat
Max Bolingbroke writes:
>> Stack space overflow: current size 8388608 bytes.
>> Use `+RTS -Ksize -RTS' to increase it.
>> I want to find out the culprit function and rewrite it tail-recursively. Is
>> there a way to find out which function is causing this error other
>> than reviewing the code m
John Lato writes:
>> I want to find out the culprit function and rewrite it tail-recursively. Is
>> there a way to find out which function is causing this error other
>> than reviewing the code manually?
> I'd like to point out that a stack-space overflow in Haskell isn't quite the
> same thing
Perhaps this is interesting? On the relationship between exploratory
(a.k.a. sloppy or theoretical) and rigorous math.
http://arxiv.org/pdf/math/9307227v1
-k
--
If I haven't seen further, it is by standing in the footprints of giants
___
Haskell-Caf
Patrick Browne writes:
> Is it possible to model partial inheritance using Haskell type classes?
> For example, if the class Bird has a flying method can we represent
> Penguins as a sub-class of Bird without a flying method?
I'm not sure the question makes sense, if "fly" is a method of class
B
"Andrew Smith B.Sc(Hons),MBA" writes:
> I'd like to add you to my professional network on LinkedIn.
Since LinkedIn tends to spam even more ambitiously than the other social
network sites, I have a procmail rule sending any mail from Linkedin to
/dev/null. But it doesn't work when it's sent via
Jason Dagit writes:
> On Thu, Aug 25, 2011 at 2:39 PM, Greg Fitzgerald wrote:
>> "cabal update" hangs. "ping haskell.org" times out. But haskell.org and
>> hackage webpages are loading just fine. What's going on?
> Lots of servers turn off ICMP packet responses these days
Because users don
Jason Dagit writes:
>>> Lots of servers turn off ICMP packet responses these days
>> Because users don't really need error messages, that's privileged
>> information for system administrators.
> Besides, if someone is trying to debug http protocol issues using
> ICMP, they're taking an awfully
yrazes writes:
> I want to compare data structure between Haskell, Java, Lisp and C. I am
> wondering if I could compare list comprehention in haskell with the vector
> class in Java, macros in common lisp and dynamic arrays in C.
You /can/ compare them, of course, but they are very different
co
Hi,
I have a program that makes use of the applicative instance for Either
String. I used to define these instances locally, but at some point,
they became part of Control.Applicative. I have limited the
dependencies to 'base >= 4', but apparently, some version 4s of base
include this instance,
Daniel Fischer writes:
>> Is there any information, or otherwise accessible source specifying
>> exactly when this was changed,
> Checking the sources, it wasn't in base-4.2.0.2 (ghc-6.12.3), but it was in
> base-4.3.1.0 (ghc-7.0.2), so it was introduced with base-4.3
Thanks to you, and every
Chris Smith writes:
> It would be a shame if we lost an occasionally useful and easy to read
You forgot "confusing"? Expecting Enum to enumerate all inhabitants of
a type seems very reasonable to me, and seems to hold for all
non-floating point types. A numeric range [a..a+n] might be expected
>> You forgot "confusing"?
> I didn't forget it
Sorry, I should have written "omitted".
> perhaps we ought to ask what the cause of the confusion is.
tr.v. e·nu·mer·at·ed, e·nu·mer·at·ing, e·nu·mer·ates
1. To count off or name one by one; list: A spokesperson enumerated the
strikers' demand
Daniel Fischer writes:
>>> Btw, -0.0 can be problematic too.
>> How so? As far as I can tell Ord and Eq treat it as equal to 0.0 in
>> every way,
> Yes. Which can be inconvenient if you are interested in whether you got a
> -0.0, so if that's the case, you can't simply use (== -0.0).
For inst
Tim Docker writes:
> mapM_ applyAction sas
Maybe you could try a lazy version of mapM? E.g., I think this would do
it:
import System.IO.Unsafe (unsafeInterleaveIO)
:
mapM' f = sequence' . map f
where sequence' ms = foldr k (return []) ms
k m m' = do { x <- m; xs <
Here's my feeble understanding of GC:
1. GC runs when after some specified amount of allocations
2. GC runs in time proportional to the live heap, which it needs to
traverse.
This means that for a long running mapM, like any other computation
generating a long list, (1) GC will run a number o
Iavor Diatchki writes:
>>> last ([0.1, 0.2 .. 0.5]) == 0.5
>> False
>>> last (map fromRational [0.1, 0.2 .. 0.5]) == 0.5
>> True
> As Ross pointed out in a previous e-mail the instance for Rationals is
> also broken:
>> last (map fromRational [1,3 .. 20])
>> 21.0
But only because it tries to
Roshan James writes:
> This gives me several warnings of the form:
> */usr/lib/haskell-packages/ghc6/lib/network-2.2.1.7/ghc-6.12.3/libHSnetwork-2.2.1.7.a(BSD.o):
> In function `sw4B_info':*
> *(.text+0x584c): warning: Using 'getservbyport' in statically linked
> applications requires at runtime
sdiy...@sjtu.edu.cn writes:
> This has nothing to do with OOP or being imperative. It's just about types.
Of course, it's not necessarily linked to OOP, but OO languages - to the
extent they have types - tend towards ad-hoc polymorphism instead of
parametric polymorphism. There are different tra
Luis Cabellos writes:
> * The main reason is that I'm not comfortable with the license
> you're using. The original code by Jeff Heard was BSD3 with an
> additional copyright notice. Your code is AGPL3. The GPL is known to
> cause problems with Haskell code due to cross module inlining. I
>
I don't know if this is relevant to your problems, but I'm currently
struggling to get some performance out of a parallel - or rather,
concurrent - program.
Basically, the initial thread parses some data into an IntMap, and then
multiple threads access this read-only to do the Real Work.
Now, th
kaffeepause73 writes:
> Thanks for the quick reply - it works now. - I wasted quite a bit time on
> this.
Alternatively, you can turn on overloaded strings, which allows constructing
text values (along with other types that are instances of IsString) from
string constants. Add
{-# Language Ov
Jerzy Karczmarczuk writes:
> Don't worry, my friend. Haskell is lazy, so there is no problem in
> "handling" those infinite modules. It will just take you an infinite
> amount of time before you get any money from such a work. But this is
> a general problem elsewhere as well.
I guess you must
Michael Snoyman writes:
> sense to try and pursue something like what you're suggesting, but I
> think the default Show (Vector Word8) should be the one most useful,
> most of the time, and I think the general consensus seems to be the
> current ByteString instance fits that role.
Hm. I think i
Rustom Mody writes:
> I remember (vaguely) a 'live page' ie where one could enter (into the
> browser) changes to the diagrams code and see the results immediately.
> Is that page there? (Or am I mixing up with something else?)
Chris Smith's web interface to Ben Lippmeier's Gloss, perhaps?
http:
Tom Murphy writes:
> Blocking/unsubscribing people based on their email provider seems... sort of
> impolite or unwelcoming.
> A greylist could work.
Greylist, as in temporarily refuse a message, and wait for the sending
mail server to retry? I don't see how it would work against hijacked
hotma
Ivan Lazar Miljenovic writes:
> Right, but first we need to define what all those terms _mean_... and
> it's no good saying your package is "stable" if you change the API in
> a large-scale fashion every release.
I think there are better criteria to use, like:
- do exported definition have Hadd
Max Rabkin writes:
> This is useful information, but to call it "stability" is not only
> misleading, but it also prevents the package from using that field to
> indicate whether or not it is stable!
Oh, right - I'm not much interested in the stability of a package. What
I want to know, is whic
Ben Franksen writes:
> An array of TVars is certainly *much* too inefficient for what I have in
> mind w.r.t. both memory and cpu time.
You must be a lot more confident than I if you say this without
benchmarking first. :-) IME, there are (at least) two possible problems
here, 1) transactions
Hi, Café,
I'm playing with STM a bit, and did a small writeup. As I'm considering
to submit it, uh, tomorrow, I was wondering if anybody would care to
take a look? I'm especially nervous about the accuracy and clarity
of my descriptions of monads and STM, which are terse and written in a
hurry.
Hi,
I just upgraded my server, and set up everything again. Except
wordpress, as 1) I'm not too fond of its user interface, and 2) it's a
big pile of PHP, difficult to keep updated, and basically a disaster
waiting to happen (and in fact, it was hacked at one point).
Before I enable it again, i
Yitzchak Gale writes:
> Gregory Crosswhite wrote:
>> could [Hackage] have a feature where when a
>> working package breaks with a new version of
>> GHC the author is automatically e-mailed?
>
> This would be nice. However, there would have to be
> a way for it to be turned on and off by the autho
Max Bolingbroke writes:
>> This is where it stranded the last time, IIRC. That sentiment makes me
>> a bit uneasy; so you are the official maintainer of a package on
>> Hackage, but you do not want to hear about it when it fails to compile?
> Don't forget that some packages fail to compile on H
:-)
> it may cause some good packages not to be uploaded by people who are
> hesitant to agree to that.
One solution could be to have a Maintainer field contain a name, but no
email address? So I could do:
Maintainer: Ketil Malde -- send email to me
or
Maintainer: Ketil Malde
Simon Michael writes:
> Did someone mention hakyll already?
Yes, Mihai, but thanks for the link. I'll probably check it out when
I'm back from vacation.
Alistair: I'm already using gitit, but I think it's usage is a bit
different.
Jason: I know about the various services, but I prefer to h
Felipe Almeida Lessa writes:
> It's funny how we, haskellers, find 'm' and 'b' descriptive names. I
> know many programmers who would cry after seeing this =).
It takes a bit of practice to get used to, but then they really are
descriptive. The trick is to keep the number of entities - paramet
John Meacham writes:
> People tend to concentrate on the lambda which cooresponds to the
> functional aspect of haskell when designing logos. Not nearly enough
> attention is paid to the other striking feature, the
What about types? This is a distinguishing feature from many of the
other lambd
serialhex writes:
> On Tue, Nov 22, 2011 at 12:22 AM, Jeremy Shaw wrote:
>
>> - honey badger - can't beat that for 'robust' and 'fearless',
>> http://www.youtube.com/watch?v=wPKlryXwmXk
> i think you were referring to this vid:
Original channel with lots of other animals and similar
commentar
David Virebayre writes:
> Also, this is café, right ? Aren't people subscribed to this list
> supposed to expect a broad range of topics ?
I don't mind a broad range of topics, but using it to collect polls is
IMHO abusing it. I guess I can dust off the killfiling features in Gnus
to deal with
Henrik Nilsson writes:
>> Just like chatter and chattee, employer and employee, there is an
>> iterator (usually as part of an enumerator/ee) and an iteratee.
> Thanks for the attempt to explain. But I, at least, remain mystified,
> and I agree with Douglas that the terminology is confusing.
FW
Johan Brinch writes:
> Can GHC eliminate one of two equal ByteStrings, when they are compared
> and turns out to be equal?
Not in general, there is no guarantee that a is identical to b, just
because a == b.
> Say i have a map, ByteString -> Int.
Data.Map.Map ByteString Int
> I now do a loo
Michael Litchard writes:
> One article addresses the question above. His answer was that he uses
> RoR which has a large community and he is therefore easily
> replaceable. My question, for freelancers in general, and web
> developers in particular is this: How do you address this question?
In t
Chris Smith writes:
>> I wonder: can writing to memory be called a “computational effect”? If
>> yes, then every computation is impure.
I wonder if not the important bit is that pure computations are unaffected by
other computations (and not whether they can affect other computations).
Many pu
"Bryan O'Sullivan" writes:
>> The question is a simple one. Must all operations on a TVar happen
>> within *the same* atomically block, or am I am I guaranteed thread
>> safety if, say, I have a number of atomically blocks in an IO
>> function.
> If you want successive operations to see a consis
John Meacham writes:
> now, you might say we can just move hackage out of the US
This might actually make things worse. The President's office is against
hurting US industry, and wants it to be mainly used to attack foreign
sites. They will not only order takedowns, but use DNS and ICANN to
enf
Yves Parès writes:
> I had for long thought that data and newtype were equivalent, but then I
> spotted some differences when it comes to strictness.
>
> data Test = Test Int
> newtype TestN = TestN Int
Interesting. I'd thought that
data Test = Test !Int
and
newtype Test = Test Int
wou
Alan Pogrebinschi writes:
> That Cabal-1.10.1.0 bug seems to be back, now with bytestring-0.9.2.1
> just uploaded to hackage.
Thanks for the link! I was banging my head on against the virtual wall,
since all I'm getting is:
% cabal install -v biopsl
Reading available packages...
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