I remember this discussion, lazy vectors would also enable an
implementation of bytestring and (maybe) text only with unboxed vectors,
unifying it all:
type ByteString = Vector Word8
2012/7/12 Evan Laforge
> he recent discussion of whether storablevector should be deprecated in
> favor of vector
Hi,
the package http://hackage.haskell.org/package/haskelldb-hdbc-mysql/ the
use of HDBC <2.3.0
I'm using cabal-install 0.14, and with a fresh install (no packages already
installed), cabal-install tries to install HDBC-2.1.1 instead of, say,
HDBC-2.2.7.0.
The problem is that HDBC-2.1.1 is old (20
> I'm not happy with any of these options.
Why are you unhappy with the ImplicitParams option?
It's pretty much like resorting to a newtype, as it's been suggested before.
2012/6/27 Tillmann Rendel
> Hi Rico,
>
> Rico Moorman wrote:
>
>> data Tree = Leaf Integer | Branch (Tree Integer) (Tree
> To move between functional and monadic code you have to completely
rewrite the code procedurally
I don't like the way people segregate "pure" from "monadic". Monadic code
*is* pure: it's written with completely pure Haskell and completely pure
combinators. As Alexander said, it's really importan
Mmmmh... no, to do that you need ImpredicativeTypes (which is I believe
about to be deprecated).
You have to declare Job a data, not a type, and use
ExistentialQuantification.
2012/6/13 Ismael Figueroa Palet
> Do you want to hide the specific types of the job? Presumably to then
> define a type
Oh my god, that was it?
I looked at your code for half an hour, and I've never thought about
that... That is really misleading.
So vector forces you to use strict ST? (That's right:
http://hackage.haskell.org/packages/archive/primitive/0.4.1/doc/html/Control-Monad-Primitive.html#t:PrimMonadshows
th
e wild guess '42 does not either ) So I guess we don't have type-level
integers for now. How are promoted Ints usable then?
[1]
http://hackage.haskell.org/trac/ghc/wiki/NewAxioms<http://hackage.haskell.org/trac/ghc/wiki/NewAxioms>
2012/6/8 AntC
> Yves Parès gmai
The doc page
http://www.haskell.org/ghc/docs/7.4.1/html/users_guide/kind-polymorphism-and-promotion.html#promotionshow
that lists are now usable as types.
So I'm trying to make a type level function to test if a type list contains
a type. Unless I'm wrong, that calls to the use of a type family.
> Then I wrote about a dozen lines of Haskell to do the job--and running
time turned out to be O(n^2).
Do you still have the code?
2012/6/1 Doug McIlroy
> > > I love Haskell. It is my absolute favorite language.
> > > But I have a very hard time finding places where I can actually use it!
> >
>
Yes, it's that one, the first Quickcheck paper, thanks.
The link on the wikipedia page is also dead.
2012/6/1 Ivan Perez
> Is this the paper you are looking for:
> http://www.eecs.northwestern.edu/~robby/courses/395-495-2009-fall/quick.pdf
> ?
>
> On 1 June 2012 11:2
Yes ^^ but I can't find this paper, Koen Claessen website doesn't mention
it and the link on the page
http://www.haskell.org/haskellwiki/Introduction_to_QuickCheck is dead.
2012/6/1 Janis Voigtländer
> Am 01.06.2012 12:00, schrieb Yves:
>
>> Out of curiosity, does someone know if QuickCheck was
Out of curiosity, does someone know if QuickCheck was the first test
framework working through test by properties associated with random
generation or if it drew the idea from something else?
Because the idea has be retaken by a lot of frameworks in several languages
(see http://en.wikipedia.org/w
Actually, I think the backtracking property here stems more from the
MonadPlus StateT instance than from the properties of Maybe.
(mplus a b runs a and b by passing explicitely the same state to them).
2012/5/28 Roman Cheplyaka
> * Yves Parès [2012-05-28 11:28:22+0200]
> > > ob
> observe $ flip runStateT 10 $ (put 0 >> mzero) <|> modify (+3)
> ((),13)
If the only thing you need is backtracking, using LogicT might be a little
overkill, using Maybe in the bottom of you monad stack suits just fine:
case flip runStateT 10 $ (put 0 >> mzero) <|> modify (+3) of
Just x -
I enclosed a source file that shows the use of a GADT in that case.
2012/5/27
> 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:
> case myData of
> myA@A{} -> fooForA's myA
> myB@B{} -> fooForB's myB
I think this would typecheck if you used GADTs.
Actually what you'd want is to use the record syntax with GADTs (there are
to add the extra type safety you want), however both are not compatible.
data ALike
data BLike
dat
> On Wed, May 23, 2012 at 09:24:06AM +0200, Ertugrul Söylemez wrote:
> > Yves Parès wrote:
> >
> > > > Note about []: Don't even mention foldl. The folding
> > > > combinator for lists is foldr, period.
> > >
> > > Yes, I do agre
ch kind of
numbers do developers work with more often? Regular Ints and Doubles or
Peano lazy numbers?)
2012/5/23 wren ng thornton
> On 5/21/12 10:51 AM, Yves Parès wrote:
>
>> I do think we have the opposite problem, however, in much Haskell code --
>>>
>> people are us
> Note about []: Don't even mention foldl. The folding combinator
> for lists is foldr, period.
Yes, I do agree. I came to this when I realized foldr gave the church
encoding of a list.
(Well, actually, due to parameters ordering:
*churchList list* z0 f = foldr f z0 list
does)
_
> If you are writing a program or system that has significant performance
requirements, you might just be better off doing the whole thing in C/C++
and living with the annoyance of doing GUIs
I fail to see how the GUI part would suffer from lack of performance if the
rest of the system is fine. I
> Not necessarily. For example the 'nub' function from Data.List could be
> much faster. Unfortunately this would also change its type. O(n²)
> complexity is really the best you can get with the Eq constraint.
Why not in that kind of cases provide a second function (named
differently), together
> I do think we have the opposite problem, however, in much Haskell code --
people are using the clean, obviously correct, but inefficient code even in
standard library functions that really should be optimized like crazy!
And even before optimizing "like crazy", I think the functions that are
"mo
When explaining monads to beginners (having an imperative background), I
found myself to say that there is *roughly* three "groups" of monads
(because they're always worried about their cost, i.e. their incidental
complexity):
- Function-oriented monads (e.g. State, Reader, Cont)
- Reductible data
> The profiler is certainly useful (and much better with GHC 7.4)
What are the improvements in that matter? (I just noticed that some GHC
flags wrt profiling have been renamed)
2012/5/16 Ben Gamari
> Kevin Charter writes:
>
> snip
> > For example, imagine you're new to the language, and as an
ations are shared between list1 and list2 (I expected
list1 to get 100% and list2 0%, due to sharing).
Strange...
2012/5/16 Anthony Cowley
> On May 16, 2012, at 12:08 PM, Yves Parès wrote:
>
> The buffer http://hpaste.org/68595 presents a simple code I tried to
> profile.
> I spotte
The buffer http://hpaste.org/68595 presents a simple code I tried to
profile.
I spotted what I strongly think to be an abusive memoization. The problem
is that I don't see how to (simply) get rid of it.
Compiled with -O2, it consumes 130MB of memory, however lines A and B
executed separately consum
> On the one hand, characterizing those who desire the best performance
possible as "simple-minded" is, at best, a gross over-generalization. Like
you, I work in a field where optimization is king (e.g., in machine
translation, program runtimes are measured in days).
You misread the logical implic
Yet this resource seems a little outdated:
http://www.haskell.org/haskellwiki/Performance/Strings does not speak about
Text
http://www.haskell.org/haskellwiki/Performance/Arrays about Vector
And what's the status of the Streams IO approach detailed in
http://www.haskell.org/haskellwiki/Performance/
One thing that baffles me is the comparison Haskell V. Java:
http://shootout.alioth.debian.org/u32/benchmark.php?test=all&lang=ghc&lang2=java
Would've expected always shorter code and better performances on average.
2012/5/8 Silvio Frischknecht
> -BEGIN PGP SIGNED MESSAGE-
> Hash: SHA1
Sorry sorry sorry ^^
I read too fast and realized I was wrong before you sent this.
Okay so then it would be nice that somewhere with higher skills tells us
where does Haskell recursive calls stand when compared to C's.
2012/5/6 Roman Cheplyaka
> It is not tail-recursive.
>
>
I do not agree: the fib function is tail-recursive, any good C compiler is
able to optimize away the calls and reduce it to a mere loop.
At least that's what I learnt about tail recursion in C with GCC.
2012/5/6 Artur
> On 06.05.2012 10:44, Ivan Lazar Miljenovic wrote:
>
>> On 6 May 2012 16:40,
Well actually, unless you _really_ need paramterizable indexes (i.e. not
only Ints) I don't see reasons to prefer array to vector now.
2012/5/4 Johan Tibell
> Hi Morten,
>
> If speed is really important I would go with the vector package. It
> has a more modern API and better performance.
>
> --
run :: Monad IO a -> IO a
Actually this type is wrong. Monad has to appear as a class constraint, for
instance :
run :: Monad m => m a -> IO a
Are you trying to make:
run :: IO a -> IO a
??
2012/5/4 Magicloud Magiclouds
> Hi,
> Assuming this:
> run :: Monad IO a -> IO a
> data Test = Test {
Why do you make your own overlay to download files via HTTP?
HXT has backends (hxt-http or hxt-curl) to do that.
Le 27 avril 2012 04:16, aditya bhargava a écrit :
> *Homepage:* http://egonschiele.github.com/HandsomeSoup
> *On Hackage:* http://hackage.haskell.org/package/HandsomeSoup
>
> *Blurb:*
So is this possible now to have a desktop PC compile your program using
template haskell into llvm bytecode and then run it on ARM?
If not, is it definitely impossible (as I said, I don't know much about
llvm) or is it "yet to be done"?
Le 10 avril 2012 19:03, Joey Hess a écrit :
> Joachim Breit
3, Joachim Breitner a écrit
:
> Hi,
>
> Am Dienstag, den 10.04.2012, 13:04 +0200 schrieb Yves Parès:
> > > All these are not cross-compiled, but natively
> > > compiled on the repective architecture, and I don’t think it is
> > easily
> > > possible to cross-co
don't use Debian?
And why was Joey Hess talking about performance issues?
(I'll be eventually interested, as Graham Klyne suggested earlier, in
compiling for Raspberry Pi, if the hardware suits).
Le 10 avril 2012 12:49, Joachim Breitner a écrit
:
> Hi,
>
> Am Dienstag, den 10.04.20
n ARM, which means GHC
can be compiled for ARM.
Le 10 avril 2012 12:27, Joachim Breitner a écrit
:
> Hi,
>
> Am Dienstag, den 10.04.2012, 11:00 +0200 schrieb Yves Parès:
> > Plus, I believed some had used GHC for smartphones?
>
> do you refer to
>
> http://www.joachim-breitne
> Other than speed, it's fine.
Do we know what speed issues are due to?
Plus, I believed some had used GHC for smartphones?
Le 9 avril 2012 01:45, Joey Hess a écrit :
> Thomas DuBuisson wrote:
> > On Sun, Apr 8, 2012 at 4:03 PM, Francesco Mazzoli wrote:
> > > No, it is not possible to build G
That would be a great idea... too bad it's an April hoax ;)
Le 1 avril 2012 21:50, John Millikin a écrit :
> There are currently several APIs for processing strict monoidal values
> as if they were pieces of a larger, lazy value. Some of the most
> popular are based on Oleg's left-fold enumerat
Plus one might argue that using <> to mean different is a bad choice, as it
graphically means "strictly inferior or strictly superior" which implies
comparability, whereas equality and comparison are two different things.
(e.g. Eq and Ord are two distinct classes in Haskell).
Le 1 avril 2012 23:06
It may come from the version of GHC you're using (Cabal version is fixed
for one specific GHC version).
Which one is it?
Le 28 mars 2012 23:05, Michael Iles a écrit :
> I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then
> tried to install snap. I get:
>
> $ cabal install sna
Think of "traverse" as a "mapA", as it's just like Data.Traversable.mapM,
but with the Applicative class constraint instead of the Monad one.
I've always wondered why it isn't called this way, sequenceM equivalent for
Applicatives is sequenceA for instance.
Le 28 mars 2012 22:19, Christopher Done
Oh, okay ^^ sorry, my bad. I should have compiled with -Wall.
So I started a repo at https://github.com/YwenP/bytestring-generic
Le 27 mars 2012 22:01, Bas van Dijk a écrit :
> On 27 March 2012 21:46, Yves Parès wrote:
> > Yes, thank you to remind me of that, I remember now having
L.Vector V.Vector a
Le 27 mars 2012 20:38, Bas van Dijk a écrit :
> On 27 March 2012 11:00, Yves Parès wrote:
> > Hello,
> >
> > As vector provides a class generalizing all flavours
> > (Data.Vector.Generic.Vector), it occurs to me that the same could be done
> &g
Hello,
As vector provides a class generalizing all flavours
(Data.Vector.Generic.Vector), it occurs to me that the same could be done
for ByteString. Then, packages based on it would have the choice between
hardcoded and generic, they wouldn't have to duplicate a module to handle
both strict and l
l:
>
> http://www.haskell.org/haskellwiki/HXT
>
> I also show some basic functionality of HXT in this blog post:
>
>
> http://adit.io/posts/2012-03-10-building_a_concurrent_web_scraper_with_haskell.html
>
> I'm curious to hear how HaXml compares to HXT / HXML / TagS
Hello café,
Provided what I read, HaXml seems to be the recommended library for parsing
XML files (I'm trying to browse and alter spreadsheets (ODS) and possibly
release a package when I'm done), is there somewhere tutorials on how to
use it?
I used 'xml' package by the past, but HaXml is more sub
Plus yampa hasn't been maintained for more than 3 years, and I lacks
documentation, which makes it a bad choice for beginners.
I don't even know what is the future of that project...
Le 23 mars 2012 09:22, Heinrich Apfelmus a
écrit :
> erik flister wrote:
>
>> giving
>>> a real-time audio synthe
e and pack function from Data.ByteString(.Lazy).
And if you want to convert your String directly to a CString (a Ptr CChar)
you better use Foreign.C.String.withCString.
Le 22 mars 2012 15:17, Yves Parès a écrit :
> This joins the question I asked two days ago here. (See
> http://haskell
This joins the question I asked two days ago here. (See
http://haskell.1045720.n5.nabble.com/Quickest-way-to-pass-Text-to-C-code-td5582223.html
)
Hope that helps.
Le 22 mars 2012 15:10, rajendra prasad a écrit :
> Hi,
>
> I have just started learning Haskell FFI. I am trying to send a string
> f
(.
castPtr)
As the function passed copies or at least does not store the pointer, I can
use unsafeUseAsCString, but then I have to manually append the
null-termination.
Le 21 mars 2012 13:09, Antoine Latter a écrit :
> On Wed, Mar 21, 2012 at 3:35 AM, Yves Parès wrote:
> > Hello,
> &g
nvenient way to convert Text into Vector?
Le 21 mars 2012 12:35, James Cook a écrit :
> On Mar 21, 2012, at 4:35 AM, Yves Parès wrote:
>
> > Hello,
> >
> > I have to interact with a C++ library that accepts as string types
> (putting c++ strings aside) pointers of wcha
Hello,
I have to interact with a C++ library that accepts as string types (putting
c++ strings aside) pointers of wchar_t (CWString in Haskell) or unsigned
32-bit int (Ptr Word32 for UTF-32 codepoints).
I have read what text, bytestring and base provide, but Text can only be
directly converted to
I might have a simpler way: make you base type polymorphic and add
capabilities to it thanks to that type:
data Base a = Base Foo Bar a
data Capa1 a = Capa1 Stuff Baz a -- We leave the 'a' so that you can
continue to "stack".
data Capa2 = Capa2 Thing Stuff -- We want it to be final, so no addit
e faster than SYB. It isn't planned to replace SYB.
>
>
> Cheers,
> Pedro
>
> [1] http://www.haskell.org/haskellwiki/Generics
> [2] http://www.cs.uu.nl/wiki/bin/view/GenericProgramming/SYB
>
>
> On Mon, Mar 12, 2012 at 16:35, Yves Parès wrote:
>
>> I'
I'd have a question concerning GHC.Generics: how does it relate to SYB's
Data.Generics?
Is it intended to replace it or complete it?
In other words: does class Data.Generics.Data class do things that class
GHC.Generics.Generic can't do?
Le 12 mars 2012 04:27, Reiner Pope a écrit :
> Hi all,
>
>
each time you need to
access it).
But I can't think of a way to check that property (list never accessed
twice) statically in Haskell.
[*] But wouldn't GHC do in that specific case do something about that with
-O2 activated?
2012/3/10 Yves Parès
> I'm afraid without uniquene
I'm afraid without uniqueness or linear typing it would be hard to avoid.
2012/3/10 Thiago Negri
> I see. Thanks for the answers.
>
> Any data structure or source annotation that would prevent that?
>
> For example, if I try the same program to run on a
> [1..] list, I'll get an
Thanks Mark!
It works also here, and even without the "-fpic" flag. Was it necessary for
you?
2012/3/8 Mark Wright
> Hi Yves,
>
> It works (on Gentoo) when I compile it as a shared library.
>
> % g++ -o libstuff.so -fpic -shared Stuff.cpp
> % ghci Main.hs -L$PWD -lstuff
> GHCi, version 7.4.1: ht
If you just need to go back and forth from String to Text, why do you need
to be generic? pack and unpack from Data.Text do the job.
Plus, in the way of what Christopher said, you can use the
OverloadedStrings extension. You can then use the string syntax at a place
that expects a text:
{-# LANGU
Sorry for the double post, but I forgot to mention I'm using GHC 7.4 and
gcc/libstdc++ 4.5.2.
(Running Ubuntu 11.04 Natty Narwhal).
2012/3/7 Yves Parès
> Hi, I'm trying to have GHCi load a haskell file that depends on a C++
> object file, which causes GHCi to fail because of a
Hi, I'm trying to have GHCi load a haskell file that depends on a C++
object file, which causes GHCi to fail because of an unknown symbol (*and I
did link with **libstdc++*), whereas the link into an executable with ghc
works and runs perfectly.
I've reduced my code to the smallest one that produc
Yes, but in 5 minutes I take it they won't have time to ask questions
before your presentation is over.
I haven't thought about parallel computing but it's one of the many assets
of the language.
The problem IMHO with STM is that it relies on too many Haskell elements to
be grasped in 5 minutes. M
Hi,
I downloaded those vim extensions, and I just wonder how I could have done
before syntastic ;)
Is there a vim plugin useful for runtime (putting breakpoints, seeing if an
expression has been evaluated or if it's still a thunk?)
I believe it exists for emacs.
2012/2/16 Nicolas Wu
> On 16 Fe
Nevermind, I think I found:
http://jduchess.org/duchess-france/blog/battle-language-a-la-marmite/
You could try the JSON parser exercise. (
https://github.com/revence27/JSON-hs) Or anything else with Parsec, it's a
pretty good power-showing library.
2012/2/28 Yves Parès
> Where exac
Where exactly does that event take place?
Is it open to public?
And I strongly disadvise fibonacci, quicksort and other mind-blowing
reality-escapist stuff. Show something real world and practical.
2012/2/27 Arnaud Bailly
> Hello Cafe,
>
> I will be (re)presenting Haskell in a "Batlle Language"
Hello,
When I was using C code from Python, the overhead put on calling C code by
Python was significant.
To simplify, say I have on C-side two procedures f and g, I do all the
stuff to call them in a row from Python, well I'm better off factorizing:
adding on C side a wrapper h procedure that call
Hi, so there are different regions libraries?
Is there a shootout comparing them, possibly also with ResourceT from
conduit (which has also been implemented in a stand-alone package
http://hackage.haskell.org/package/resource-simple-0.1 by Robin Banks), for
I take it it tries to respond to the same
to use regular Ptrs with Foreign.Marshall.Alloc.malloc
2012/2/12 Antoine Latter
> On Sun, Feb 12, 2012 at 3:09 PM, Yves Parès wrote:
> > But then,
> > In use case 1), how can a Haskell function modify the data addressed?
> >
>
>
> http://hackage.haskell.org/packages/archive/base/latest/doc/h
), that mostly limits their interest, doesn't it?
2012/2/12 Albert Y. C. Lai
> On 12-02-12 09:18 AM, Yves Parès wrote:
>
>> According to the documentation
>> (http://hackage.haskell.org/**packages/archive/base/4.5.0.0/**
>> doc/html/Foreign-StablePtr.**html<ht
/2/12 Antoine Latter
> On Sun, Feb 12, 2012 at 8:18 AM, Yves Parès wrote:
> > Hello,
> >
> > According to the documentation
> > (
> http://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Foreign-StablePtr.html
> ),
> > StablePtrs aims at being opaq
Hello,
According to the documentation (
http://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Foreign-StablePtr.html),
StablePtrs aims at being opaque on C-side.
But they provide functions to be casted to/from regular *void**'s.
Does that mean if for instance you have a StablePtr CInt
ng, but it's just I don't picture the overhead being so huge in
that case. What so big would the runtime need to keep in memory except for
the closure that generates the infinite list?
2012/2/10 Aleksey Khudyakov
> On 10.02.2012 18:38, Yves Parès wrote:
>
>> I just thou
I just thought about something: basically all these APIs provides a "IO
[a]" (where a is a randomly generable type) function.
Is there a problem with the approach that is to rely on lazy evaluation to
pass to pure code (either explicitely or through State) the infinite list
generated in IO and cons
Hi,
I've been in the past told that mersenne-random was much better than the
standard random package.
However, System.Random.Mersenne doesn't follow the general API described in
System.Random, MTGen is not an instance of RandomGen.
But a sample on System.Random.Mersenne.getStdRandom documentation
Why do you think it's a lot? MVar are a teeny tiny and convenient primitive
of communication, and I don't see why they wouldn't suit your need.
Sure a throwTo would do the trick... But they're is "do the trick" and "do
the job", you see?
Using STM and TVars *would* be kind of overkill.
2012/2/8
Are there documentation on constraints being types, how they can be
declared/handled and what are the interests?
2012/2/7 Mikhail Vorozhtsov
> On 02/06/2012 03:32 AM, Gábor Lehel wrote:
>
>> There's a common pattern in Haskell of writing:
>>
>> data E where E :: C a => a -> E
>> also written
>
wo list of MyTuple is just base on its first
> element.
> Basically it means: [(1,2), (2,2)] `union` [(1,0), (2,0), (0,0)]
> produce [(1,2), (2,2), (0,0)]
> rather than [(1,2),(2,2),(1,0),(2,0),(0,0)] by default.
>
> -Haisheng
>
>
>
> On Sun, Feb 5, 2012 at 11:37
That is a great initiative.
I didn't know about those Kind extensions that enable you to pass a
typeclass as a type parameter...
However, have you considered putting the Data.Exists.Default module in a
separate package? That would reduce the dependencies for those who just
need Exists and Existent
> For instance your Eq instance could have been written
> x == y = (==) `on` (fst . getTuple)
Sorry, wrong arity:
(==) = (==) `on` (fst . getTuple)
Okay for the imperative code.
2012/2/5 Yves Parès
> Concerning your first solution, I don't understand why you redefine Eq but
>
Concerning your first solution, I don't understand why you redefine Eq but
not Ord instance. Ord will still work by comparing the tuples and not the
first elements of said tuples.
Plus the good news is you don't have to do this: just use regular tuples
and use sort*By *or group*By *functions from D
Have you tried to compile your code with optimisations? I guess GHC's
strictness analysis would find strict evaluation is better here.
2012/1/30 Joey Hess
> Claude Heiland-Allen wrote:
> > Control.Monad.State.Strict is strict in the actions, but the state
> > itself is still lazy, so you end up
f pure closure-based automata)
2012/1/28 Erik de Castro Lopo
> Yves Parès wrote:
>
> > Yes, and IMO this is a growing problem. Since iteratees were designed, a
> > lot of different libraries providing this kind of service have appeared.
>
> Thats mainly because the solution sp
> http://hackage.haskell.org/package/network-server
Straightforward to use, but unfortunately uses "unix" package. I take it it
is not portable.
However its first version did not use it, so maybe the concerned part could
be rewritten.
> I think there is still no consensus on which iteratee librar
If I consider the functions head, length, elem & sum, each is of them is
strict, as:
head/length/elem x/sum _|_ are always _|_.
However:
head (x:_|_) is never _|_.
length [_|_, _|_, _|_ ...] is also never _|_.
elem x [4,5,6,8,2,90,_|_,_|_ ...] is *only sometimes *_|_ (depending on x
value).
In fac
One day, I _really_ should learn all GHCI commands...
Thanks, Felipe ^^
2012/1/25 Felipe Almeida Lessa
> On Wed, Jan 25, 2012 at 7:38 PM, Yves Parès wrote:
> > But I haven't found a way to tell GHCI to fully evaluate 'x' but _not_
> print
> > its value.
>
Hi, nice little package!
I just made a fork and added a new function makeHTrace to be able to have
separate variables 'level'.
I also add the htrace type signature (or else haddock won't generate
documentation for this module):
https://github.com/YwenP/htrace
I was also investigating in a way to
Hello,
By randomly typing : under GHCI, I discovered it could be used as a
debugger (:breakpoint, :step, etc.)
Three questions in that regard:
1) Is there some documentation about it?
2) I haven't investigated much, is that fairly thorough and convenient?
Does some people over here use those funct
I may be curious to see how you intend to use such enum...
It is very C-wise, I'm not sure it will be very handy, but I need some
context.
2012/1/22 Данило Глинський
> What is natural Haskell representation of such enum?
>
> enum TypeMask
> {
>UNIT,
>GAMEOBJECT,
>
>CREATURE_OR_GAMEOB
Big sum up of everything:
If TestN is a newtype constructor, then
'TestN undefined' and 'undefined' are exactly the same thing.
2012/1/22 Yitzchak Gale
> Yves Parès wrote:
> >> Is there some litterature expliciting in a less empiric way than I did
> the
>
atched against ⊥.
Put shorter:
newtype TestN = TestN Int
TestN x = undefined
Then x = undefined.
Which means you cannot make a boxed type out of un unboxed one using
newtype. That makes sense.
2012/1/22 Roman Cheplyaka
> * Yves Parès [2012-01-22 11:32:30+0100]
> > These make me thin
Hello,
I had for long thought that data and newtype were equivalent, but then I
spotted some differences when it comes to strictness.
Those can be summed up as:
data Test = Test Int
newtype TestN = TestN Int
pm (Test _) = 12 -- Strict (pm undefined = undefined)
pm2 t = t `seq` 12 -- Strict
> (StrictT op) >>= f = StrictT (op >>= \ x -> x `seq` runStrictT (f x))
Are you sure? Here you evaluate the result, and not the computation itself.
Wouldn't it be:
(StrictT op) >>= f = op ` seq` StrictT (op >>= \x -> runStrictT (f x))
??
2012/1/21 David Barbour
> On Sat, Jan 21, 2012 at 10:0
uvector is deprecated, its functionnalities has been ported into vector.
2012/1/11 Artyom Kazak
> Also, uvector already supports unboxed Ratios:
> http://hackage.haskell.org/package/uvector
>
> In fact, I am surprised that Data.Vector doesn't have a Ratio
> instance, but has a Complex instance.
2012/1/6 AUGER Cédric
> when you write "forall a. exists b. a -> b -> a", then you allow the
> caller to have access to b to produce a (didn't you write "a->b->a"?)
>
Yes, sorry, I always assumed independence between the type variables. Like
in:
f :: forall a. a -> (forall b. b -> a)
being the s
Something) -> SomethingElse
And to be sure:
foo :: forall a. a -> (forall b. b -> a)
is equivalent to:
foo :: forall a b. a -> b -> a
Right?
And:
foo :: forall a. a -> ((forall b. b) -> a)
to:
foo :: forall a. exists b. a -> b -> a
??
2012/1/4 AUGER Cédric
> Le Wed, 4
id so f will decide what will be its type. In this case, because
it's applied to 'x', id type will get instanciated to 'a -> a' (where a is
rigid, because bound by f signature).
2012/1/4 AUGER Cédric
> Le Wed, 4 Jan 2012 14:41:21 +0100,
> Yves Parès a écrit :
>
;
> f :: Int -> Int
> f x = undefined :: a
>
> f :: Int -> Int
> f x = 3 :: (Num a => a)
>
>
> Can someone explain case by case?
>
> Thanks,
> Thiago.
>
> 2012/1/4 Yves Parès :
> >> I don't see the point in universally quantifying over typ
" the scoping of variables, so that
> f :: a -> a
> f x = x :: a
> becomes valid?
You mean either than compiling with ScopedTypeVariables and adding the
explicit forall a. on f? I don't think.
2012/1/4 Brandon Allbery
On Wed, Jan 4, 2012 at 08:41, Yves Parès wrote:
> Wo
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