This seems like a bug in GHC. But it has nothing to do with MVars. I've
narrowed this down and filed a bug report here:
http://hackage.haskell.org/trac/ghc/ticket/7528
Timothy
-- Původní zpráva --
Od: Yuras Shumovich shumovi...@gmail.com
Datum: 24. 12. 2012
Předmět: Re:
I'm not sure that there is anything great about this bug. It seems to me
to be a rather severe demonstration of a somewhat already known design flaw
in the runtime :(
Could you please comment on the actual bug rather than replying here so that
the devs see that this behaviour has been
The real question is, does this mean that GHC is stopping the world every
time it puts an MVar?
Tim
-- Původní zpráva --
Od: Brandon Allbery allber...@gmail.com
Datum: 24. 12. 2012
Předmět: Re: [Haskell-cafe] multi-thread and lazy evaluation
On Mon, Dec 24, 2012 at 8:45 AM,
I created that for a specific application I was writing, where I was saving
the data directly to disk. I modularized as an afterthought. But I don't
see anything wrong with using types that have JS in their names. It is
STILL a haskell data structure. Just one which can be converted to a
Also GTK, but I ran across this a little while ago http://hackage.haskell.
org/package/barrie not sure if it still builds as it's a bit old, but it
looked interesting.
-- Původní zpráva --
Od: Rune Harder Bak r...@bak.dk
Datum: 1. 12. 2012
Předmět: Re: Re: [Haskell-cafe] Simple
I know it's not wx, but if you were willing to use GTK, you could simply
install:
http://hackage.haskell.org/package/gtk-jsinput
and generate the form automatically as described in:
https://github.com/timthelion/gtk-jsinput/blob/master/Graphics/UI/Gtk/
Custom/JSInput.hs
Timothy
Could you give us more info on what your constraints are? Is it necessary
that you have a certain number of connections per second, or is it necessary
that the connection results very quickly after some other message is
received?
-- Původní zpráva --
Od: Johan Tibell
What triggers GC in haskell? We obviously aren't using Java's method of GC
as needed(for good reasons, Java's method is terrible because you get slow
downs when you need speed the most). But we should be able to learn
something from Java and have a gc::IO() method that one could call BEFORE a
I've read a lot of negative regarding the problems with cabal and hackage.
I've written quite a few of them myself.
I want to propose a simple change in philosophy of packages.
Haskell has inherited a philosophy from the imperative world,
that there are two types of packages:
Libraries and
Well in some cases, it might not be easy to break up the libraries. If
there is sufficient mutual dependency, doing so won't even help the
situation. However, I already looked at the code to some large libraries,
such as xmonad-contrib, and gtk2hs and am certain that no code modifications
are
I understand your concern. Of course with cabals current implementation
this proposal requires a lot of fluff. I thought about implementing a cabal
syntax directly into Haskell pragmas, getting rid of the cabal file format
entirely. I think that would be a pie in the sky optimum. However, I
You are correct this won't help(and may even hurt) in places where there is
true mutual inter-dependency between parts of libraries. But I gave
examples where I was sure this was not the case.
Timothy
-- Původní zpráva --
Od: Brandon Allbery allber...@gmail.com
Datum: 18. 11.
This smells like homework to me,
which isn't a bad thing,
it will however change the way I answer you.
Please look at http://hackage.haskell.org/packages/archive/base/latest/doc/
html/Data-List.html#v:permutations
and show us your attempts to use this function.
Timothy
-- Původní
Hello,
There are several packages without haddock documentation on hackage. The
one that bugs me right now, is the latest version of gtk2hs: http://hackage.
haskell.org/package/gtk
I've been told that this may be due to hackage updating docs with an
infrequent cron job, so that new packages
I agree with Andreas, we need a package recall method. This should be an
ability granted only to certain people, so that all of hackage cannot be
deleted by one rogue user with recall privileges, but this is still a
necessary feature.
Timothy
-- Původní zpráva --
Od: Andreas
Hello,
I have a very general question that doesn't exactly relate to Haskell. Do I
need to worry about hard drive thrashing with a modern controller? I
understand, that such thrashing can significantly reduce the lifespan of
modern SSD drives.
For example, if I do:
import Control.Monad
foo =
Hmm. I was hoping for good news that things had changed for the better :( .
I want these files to be on the disk so I don't lose data in the case of
failure. A common solution here is to acidify the program, but that is not
acceptable from a usability standpoint. I don't want to have the
Hello,
I'm writing a function to find out if a given directory is empty. I came up
with the obvious:
do{
contents - getDirectoryContents /home/timothy/works/current/anonGraph/
empty/ ;
let
realContents
=
filter
(\file -
case file of
. - False ;
.. - False ;
Thanks! That is a neat way. At least for exceptions which I know to exists
and know how to trigger ;)
Tim
-- Původní zpráva --
Od: Albert Y. C. Lai tre...@vex.net
Datum: 7. 11. 2012
Předmět: Re: [Haskell-cafe] Where is the documentation on exception types
kept?
On 12-11-07
I am subscribed to the xmonad mailing list. But the question still stands.
The list is pretty quiet and it seems xmonad is maintainerless :(
-- Původní zpráva --
Od: Roman Cheplyaka r...@ro-che.info
Datum: 5. 11. 2012
Předmět: Re: [Haskell-cafe] Is XMonad still developed or
To be clear, the project ArchHaskell has little or no relation to my
original post. If I understand correctly, ArchHaskell is a set of Arch uses
who attempted to repackage the packages in hackage in the AUR. This
addresses issues of package management that are unrelated to my complaint.
My
Hello,
Who is in charge of the ghc and haskell packages on Arch linux? The current
system isn't working.
Arch linux tends to update packages very quickly.
For ghc, always having the latest ghc isn't a good thing. At least if you
actually want to get some work done. A majority of the time the
I didn't wish to suggest that the latest version shouldn't be available. If
you read my entire message, the suggestion I made, is that arch should
install the latest with the next to latest in parallel and do so by default
rather than as some weird and hacky work-around.
Sending pull
Actually Arch has been accommodating in other cases when there was a stable
library and a new/developing. It certainly keeps around two versions of
python, autoconf, GTK, qt, gambas... The solution I'm proposing would be a
little different than those cases, but on the same principle.
Use a tuple: (Result,Maybe Error) rather than an Either. Do everything
lazily, and in the case of an error, undo the result.
-- Původní zpráva --
Od: Eric Velten de Melo ericvm...@gmail.com
Datum: 11. 9. 2012
Předmět: [Haskell-cafe] Either Monad and Laziness
Hello,
I am
So I've been playing with the median problem today. Not sure why, but it
stuck in my head.
import Data.List
import Control.Monad.ST
import Data.STRef
import Control.Monad
I've been using the hashing algorithm that I described last night, but it's
quite slow. I must be missing something
Thanks for the advice. After taking most of it it is faster. But it is
still many times slower than it ought to be! This algorithm should be much
faster than simply sorting the list, and yet it is more than twice as slow!
One note, you said:
Increment length.
modifySTRef
lengthRef
(+1)
Aha!!! Now it's working. Just had to compile with -O2 :D :D
Now I'm over twice as fast for a list of 2 million! With better length
based analysis of how many buckets should be used, this number can be
improved.
You can feel free to use my code however you like. I've attached the final
The problem with the last example I gave is evident in your statement It
appears you need to distinguish between Bars and Frogs. I have written
quite a number of largish code bases, and I've run into the following
problem every time:
case largeMultiConstructorTypedValue of
The thing is, that one ALWAYS wants to create a union of types, and not
merely an ad-hock list of data declarations. So why does it take more code
to do the right thing(tm) than to do the wrong thing(r)? Lets take an
example from Conor McBride's she https://github.com/timthelion/her-lexer/
Looks like I failed to reply all
-- Původní zpráva --
Od: timothyho...@seznam.cz
Datum: 2. 9. 2012
Předmět: Re: Re: [Haskell-cafe] Over general types are too easy to make.
Care to link me to a code repository that doesn't have this problem? The
only Haskell program that I have
It really depends on how you are reading in the data and what you plan to do
with it besides taking the median. Obviously, if you read in your data as
an ordered list things can be done O(n) without any trouble.
In another case, if you already know the range, you can make a hash table
and
Sorry, I am horribly mistaken. Hash table is O(n)+O(numbuckets)+O
(middlebucketsize log(middlebucketsize))... It's too late for this stuff...
Tim
-- Původní zpráva --
Od: timothyho...@seznam.cz
Datum: 3. 9. 2012
Předmět: Re: [Haskell-cafe] hstats median algorithm
It really
So after having played with it a little, it looks like GADTs are the way to
go. The method of manipulating the module system won't work because of two
reasons:
A) How can a user pattern match against data constructors that are hidden by
the module system?
B) It's an awful hack.
Do I
I'd have to say that there is one(and only one) issue in Haskell that bugs
me to the point where I start to think it's a design flaw:
It's much easier to type things over generally than it is to type things
correctly.
Say we have a
data BadFoo =
BadBar{
badFoo::Int} |
BadFrog{
Sure, but that's relying on the promise that you're passing it a valid
BadFrog... Consider then:
deBadFrog $ BadFrogType (BadBar { badFoo = 1})
-- Původní zpráva --
Od: John Wiegley jo...@newartisans.com
Datum: 31. 8. 2012
Předmět: Re: [Haskell-cafe] Over general types
And of course the biggest reason for this change, is we want GHC to continue
to become smarter. Remember, Haskell is a high level language. The
original promise, is that the code should be algebraically optimizable by
the compiler itself. Yes, of course many Haskell coders have learned to
deal
So that we are using concrete examples. here is an example of a change that
really shouldn't break any package:
https://github.com/timthelion/threadmanager/commit/c23e19cbe78cc6964f23fdb90
b7029c5ae54dd35
The exposed functions are the same. The behavior is changed. But as the
commiter
Can we have at least 5 consonants? There are enough people with names such
as Srbský in eastern European In fact, the Czechs can make use of as
many as 9 consonants in a row! http://ld.johanesville.net/perlicky/03-
jazykova-nej-a-jine-hricky
On a side note, image based CAPACHA's can
There's always this, for ALL types a :( So even where you would think that
the documentation can claim that a given Eq instance follows the law of
commutativity, it really cannot.
Prelude Control.Concurrent System.IO.Unsafe do m - newEmptyMVar ;putMVar m
1 ; print $ (unsafePerformIO (do v -
Your Maybe example is very contrived. The place where I ran into this was
much less contrived I think.
I have an editor for a visual programming language. That looks like this:
https://github.com/timthelion/gridhaskell-haskarrow/wiki
I'm using a modified version of the Document-View model for
Somehow I don't understand you.
Could you please fill out your example into a working bit of code?
Thank you,
Timothy
-- Původní zpráva --
Od: Yves Parès limestr...@gmail.com
Datum: 27. 5. 2012
Předmět: Re: [Haskell-cafe] Record syntax, reopening a can of worms.
case
Hello list,
As my first post. I'd like to open a can of worms that I sure has been
opened before. That is record syntax.
As we all know, there are some type safety problems with our current record
syntax. The most obvious is that this compiles without even giving you a
warning:
data MyData =
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