Jeremy,
The problem you're trying to solve might seem tricky but it is in fact
quite solvable. In Feldspar[1] we use monads quite frequently and generate
code from them, in a similar fashion to what you're trying to do. We've
written a paper about how we do it[2] that I welcome you to read. If
Hi,
I'm putting together a cabal package and I'd like to have some code
examples in my description file. In particular I would like to have a code
block containing markdown containing a code block of Haskell, like this:
~~~{ .haskell }
module Main where
main = putStrLn Hello World!
~~~
://hackage.haskell.org/packages/archive/shpider/0.2.1.1/doc/html/Network-Shpider.html
On 04/02/13 12:30, Josef Svenningsson wrote:
Hi,
I'm putting together a cabal package and I'd like to have some code
examples in my description file. In particular I would like to have a
code block
should be fine if you follow Haddock formatting. For example:
http://hackage.haskell.org/package/lens
Is from the cabal file:
http://hackage.haskell.org/packages/archive/lens/3.8.5/lens.cabal
Ryan
On Mon, Feb 4, 2013 at 7:30 AM, Josef Svenningsson
josef.svennings...@gmail.com wrote:
Hi
documentation for now.
Thank you very much!
Josef
Ryan
On Mon, Feb 4, 2013 at 8:37 AM, Josef Svenningsson
josef.svennings...@gmail.com wrote:
Hi Ryan,
As far as I can tell I'm following the Haddock formatting just fine. I'm
using bird tracks for my code block and according to the Haddock
On Thu, Dec 15, 2011 at 7:04 PM, Dimitrios Vytiniotis
dimit...@microsoft.com wrote:
I've a quick question:
Are there Haskell wrappers for the Z3 C API around?
I believe sbv recently got support for Z3 but I don't know if it uses the
C API. Neither have I tried the Z3 backend, I only played
Hi cafe!
I'm hitting a very strange problem when using haskell-src-exts and
haskell-src-exts-qq. Consider the following module:
\begin{code}
{-# Language QuasiQuotes #-}
module TestBug where
import Language.Haskell.Exts
import Language.Haskell.Exts.QQ
unit = TyTuple Boxed []
ty = [dec| quux
On Thu, Mar 17, 2011 at 10:58 PM, Niklas Broberg
niklas.brob...@gmail.comwrote:
I already export a partial parser for top-of-file pragmas,
I see. What I don't see is how such a parser would return the rest of
input.
Hmm. I see. And I see that you are correct in not seeing it, since it
On Thu, Nov 25, 2010 at 11:32 AM, Joachim Breitner m...@joachim-breitner.de
wrote:
Hi,
although semantically it could, ghc does not do common subexpression
elimination (CSE), at least not in every case. The canonical example
where it would be bad is the function (with div to avoid numerical
Fiddling with GHC internals sounds like overkill for this project.
Are you really sure you need a timeout to run the Haskell metaprogram? There
are many implementations of EDSLs which take the approach that you want to
take by using Haskell to create a syntax tree and the offshore it to some
On Mon, Aug 23, 2010 at 6:10 PM, Max Rabkin max.rab...@gmail.com wrote:
(Accidentally sent off-list, resending)
On Mon, Aug 23, 2010 at 15:03, Eugene Kirpichov ekirpic...@gmail.com
wrote:
* Difference lists
I mean that not only higher-order facilities are used, but the essence
of the
On Fri, Aug 20, 2010 at 6:05 AM, Jason Dagit da...@codersbase.com wrote:
On Thu, Aug 19, 2010 at 8:05 PM, Michael Litchard mich...@schmong.orgwrote:
I'd like the community to give me feedback on the difficulty level of
implementing an awk interpreter. What language features would be
On Tue, Mar 23, 2010 at 11:52 AM, Ozgur Akgun ozgurak...@gmail.com wrote:
Can a user define a derivable type class of her own? If yes, how?
GHC has a feature which lets you define classes such that making an
instance of them is as easy as deriving. It's called Generic classes.
See GHC's
On Mon, Oct 12, 2009 at 6:22 PM, Kim-Ee Yeoh a.biurvo...@asuhan.com wrote:
Does anyone know if it's possible to write the following:
** :: (Applicative m, Applicative n) =
m (n (a-b)) - m (n a) - m (n b)
Clearly, if m and n were monads, it would be trivial.
Rereading the original paper, I
Conor,
I'd like to point out a few things that may help you on the way.
On Wed, Apr 15, 2009 at 8:58 PM, Conor McBride
co...@strictlypositive.org wrote:
I don't immediately see what the clash in that context would be - I
*think* what you propose should be doable. I'd be interested to know
On Mon, Feb 16, 2009 at 2:30 AM, wren ng thornton w...@freegeek.org wrote:
Louis Wasserman wrote:
I follow. The primary issue, I'm sort of wildly inferring, is that use of
STT -- despite being pretty much a State monad on the inside -- allows
access to things like mutable references?
On Wed, Dec 10, 2008 at 5:34 AM, Don Stewart [EMAIL PROTECTED] wrote:
I'd like to echo Jason's remarks earlier.
http://www.reddit.com/r/haskell_proposals/
We've tried for a couple of years now to efficiently track 'wanted
libraries' for the community, but never with much success.
In
2008/11/27 Galchin, Vasili [EMAIL PROTECTED]:
Hello,
I am reading re-reading Prof. Wadler paper
Proofs are Programs: 19th Century Logic and 21st Century Computing
but also want to re-read watch his video on same subject.
Is it this talk you're after?
On Wed, Nov 26, 2008 at 11:14 PM, David Menendez [EMAIL PROTECTED] wrote:
How old is nhc? I've always thought of it as one of the big three,
but I don't really know how far back it goes compared to ghc.
The following page suggests that it was released mid 1994 but there
could of course have
On Mon, Oct 6, 2008 at 2:58 PM, Cale Gibbard [EMAIL PROTECTED] wrote:
2008/10/6 Don Stewart [EMAIL PROTECTED]:
dagit:
data and newtype vary in one more subtle way, and that's how/when they
evaluate to bottom. Most of the time they behave identically, but in the
right cases they act
On Fri, Sep 26, 2008 at 7:18 PM, Stephan Friedrichs
[EMAIL PROTECTED] wrote:
apfelmus wrote:
[..]
Persistent data structures are harder to come up with than ephemeral
ones, [...]
Yes, in some cases it's quite hard to find a persistent solution for a
data structure that is rather trivial
On Fri, Jun 27, 2008 at 12:39 PM, Claus Reinke [EMAIL PROTECTED] wrote:
Assuming I get it included, is there any features in particular you'd
want to
see in there? Note that if I do have it produce visualisations, they'll
be
static images as part of an analysis report rather than being
be the cause of this. Hopefully someone with a bit more cabal
knowledge can help out.
Good luck,
Josef
On Sat, May 17, 2008 at 11:02 AM, Josef Svenningsson
[EMAIL PROTECTED] wrote:
On Sat, May 17, 2008 at 1:00 PM, Galchin, Vasili [EMAIL PROTECTED]
wrote:
Josef,
E.g.
[EMAIL PROTECTED
Vasili,
I have pretty much exactly the same set up as you seem to have. I
haven't had a single problem with running configure using cabal. In
what sense does it stop working?
Cheers,
Josef
2008/5/17 Galchin, Vasili [EMAIL PROTECTED]:
PS I have always installed ghc first via the Ubuntu package
2008/3/9 Galchin Vasili [EMAIL PROTECTED]:
I am playing around with the STM API. I would like to see examples of
STM other than the Santa.hs as I am having problems with STM vs IO.
Here's my implementation of the Dining Philosophers in STM:
On Feb 6, 2008 3:06 PM, Miguel Mitrofanov [EMAIL PROTECTED] wrote:
On 6 Feb 2008, at 16:32, Peter Padawitz wrote:
Can anybody give me a simple explanation why the second definition
of a palindrome checker does not terminate, although the first one
does?
pal :: Eq a = [a] - Bool
pal
On Dec 28, 2007 11:40 PM, Mitar [EMAIL PROTECTED] wrote:
Would not it be interesting and useful (but not really efficient) to
have patterns something like:
foo :: Eq a = a - ...
foo (_{4}'b') = ...
which would match a list with four elements ending with an element 'b'. Or:
foo
This sounds like a fun project and it is certainly feasible to do. I
thought I'd give you some pointers to fun stuff that people have been
doing in the past.
Thomas Reps have been doing program analysis since the dawn of time,
but one paper that seems particularly related to what you try to do is
On Nov 20, 2007 4:32 PM, Ian Lynagh [EMAIL PROTECTED] wrote:
Hi Brad,
On Tue, Nov 20, 2007 at 09:50:02PM +1000, Brad Clow wrote:
$ ./test
23
24
I can't reproduce this. Can you please tell us what platform you are on
(e.g. x86_64 Linux) and what gcc --version says?
Also, where did
On 10/29/07, Bulat Ziganshin [EMAIL PROTECTED] wrote:
you may also look at these data:
1,225,416 bytes allocated in the heap
152,984 bytes copied during GC (scavenged)
8,448 bytes copied during GC (not scavenged)
86,808 bytes maximum residency (1 sample(s))
3
On 10/30/07, Henning Thielemann [EMAIL PROTECTED] wrote:
When following the description on
http://www.haskell.org/haskellwiki/How_to_write_a_Haskell_program#Add_some_automated_testing:_QuickCheck
then darcs will run the QuickCheck tests on each 'darcs record', but the
new patch is also
On 10/28/07, Isaac Dupree [EMAIL PROTECTED] wrote:
Josef Svenningsson wrote:
Less bogus timing:
avg4: 18.0s
avgS: 2.2s
avgP: 17.4s
OK, so these figures make an even stronger case for my conclusion :-)
Single traversal can be much faster than multiple traversals *when
done right
On 10/29/07, Josef Svenningsson [EMAIL PROTECTED] wrote:
But using those flags yielded a very interesting result:
avgP: 4.3s
Superlinear speedup!? As you say, I would have expected something
slightly larger than 9s. I think what happens here is that for avg4
the entire list has to be kept
On 10/26/07, Dan Weston [EMAIL PROTECTED] wrote:
Thanks for letting me know about the Data.Strict library on Hackage. I
will definitely make use of that! BTW, you left out an import
Data.List(foldl') in your example.
Yes, Data.Strict can be pretty handy for getting the right strictness.
Sorry
Sorry for reacting so late on this mail. I'm digging through some old mails...
On 10/12/07, Dan Weston [EMAIL PROTECTED] wrote:
Always check optimizations to make sure they are not pessimizations!
Actually, traversing the list twice is very cheap compared to space
leakage, and accumulating
On 10/24/07, Neil Mitchell [EMAIL PROTECTED] wrote:
Hi
Are there binary constants in Haskell, as
we have, for instance, 0o232 for octal and
0xD29A for hexadecimal?
No, though it is an interesting idea.
You can get pretty close with existing Haskell though:
(bin 100010011)
On 9/6/07, Simon Marlow [EMAIL PROTECTED] wrote:
Ketil Malde wrote:
I, on the other hand, have always wondered why the strict arrays are
called unboxed, rather than, well, strict? Strictness seems to be
their observable property, while unboxing is just an (admittedly
important)
On 8/10/07, John Meacham [EMAIL PROTECTED] wrote:
On Thu, Aug 09, 2007 at 06:37:32PM +0100, Andrew Coppin wrote:
Which of these is likely to go faster?
type Quad = (Bool,Bool)
...
data Quad = BL | BR | TL | TR
...
I'm hoping that the latter one will more more strict / use less space.
On 8/3/07, Chris Smith [EMAIL PROTECTED] wrote:
Neil Mitchell [EMAIL PROTECTED] wrote:
I'm not convinced either, a nice concrete example would let people
ponder this a bit more.
I tried to provide something in my response to Simon. Here it is again:
One could sugar:
do tax -
On 7/26/07, Jon Harrop [EMAIL PROTECTED] wrote:
Does Haskell have anything similar to OCaml's polymorphic variants?
No as such, but it's possible to simulate them. As always Oleg was the
one to demonstrate how:
http://okmij.org/ftp/Haskell/generics.html
Cheers,
Josef
Michael,
I think what you're trying to do is perfectly doable in Haskell and I think
the right tool for it is arrows, as Tomasz Zielonka mentioned before. I
suggest you take a look at the following paper which uses arrows to enforce
security levels in the code:
On 7/6/07, Thomas Hartman [EMAIL PROTECTED] wrote:
I am a total quickcheck noob. Is there a way to find out what predicate test
function is, below?
The trick that I know of to do that is to not generate a function in
the first place, but a data type which can represent various functions
of
On 6/30/07, Jon Cast [EMAIL PROTECTED] wrote:
On Friday 29 June 2007, Jon Cast wrote:
Here's my solution (drawn from a library I'll be posting Real Soon Now):
snip solution
I forgot to point out that this is 75-90% drawn from a library called
Fudgets[1], which is probably the most extended
On 6/21/07, Michael T. Richter [EMAIL PROTECTED] wrote:
Is there a good book or web site outlining decent pure-lazy-functional
data structures, with or without code samples?
Chris Okasaki's publication page is a goldmine when it comes to functional
data structures, lazy and otherwise.
I think both Benja's and David's answers are terrific. Let me just add
a reference.
The person who's given these issues most thought is probably Per
Martin-Löf. If you want to know more about the meaning of local
connectives you should read his On the Meanings of the Logical
Constants and the
Hi,
Just a small comment on one of the comments.
On 5/1/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
Also, rather than this:
add :: Bloom a - a - Bloom a
a better argument order is this:
insert :: a - Bloom a - Bloom a
That way, you can use it with foldr.
Hmmm. If you want to
On 4/24/07, Jacques Carette [EMAIL PROTECTED] wrote:
In Ocaml, you can frequently use polymorphic variants to get the same
effect.
Which means that if you are willing to do enough type-class-hackery, it
should, in principle, be possible to do the same in Haskell. But it
sure isn't as
On 4/21/07, Donald Bruce Stewart [EMAIL PROTECTED] wrote:
chak:
Duncan Coutts wrote:
If anyone is interested in developing a Language.C library, I've just
completed a full C parser which we're using in c2hs.
It covers all of C99 and all of the GNU C extensions that I have found
used in
Hi,
Just a comment or two on the implications of converting higher-order
functions to data.
The paper you reference about this uses the method of
defunctionalization. This is a whole program transformation and might
therefore not be suitable in a compiler such as GHC or YHC. On the
other hand,
On 3/8/07, John Meacham [EMAIL PROTECTED] wrote:
it seems we can almost do this now without adding any new API calls,
just have 'thawArray' and 'freezeArray' perform the check, and behave
like 'unsafeThawArray' or 'unsafeFreezeArray' when they are the only
reference.
The compiler may even be
On 1/20/07, Brian Hulley [EMAIL PROTECTED] wrote:
Neil Mitchell wrote:
Hi Brian,
Is there any solution that would allow excess laziness to be removed
from a Haskell program such that Hask would be a category?
class Seq a where
seq :: a - b - b
Then you have a different seq based on
On 1/11/07, Yitzchak Gale [EMAIL PROTECTED] wrote:
Josef Svenningsson wrote:
Take the state monad for example. Should it be
strict or lazy in the state that it carries
around? What about the value component?
...both strict and lazy variants are useful.
I wrote:
Are those really needed
Yitzchak,
I agree with you that both lazy and strict monads are important and
that we should have both options in a monad library.
But the fun doesn't end there. There are other strictness properties
to consider. Take the state monad for example. Should it be strict or
lazy in the state that it
On 1/10/07, Yitzchak Gale [EMAIL PROTECTED] wrote:
Hi Josef,
Josef Svenningsson wrote:
...the fun doesn't end there. There are other strictness properties
to consider.
Could be. But after using mtl heavily for a few years now,
I find that in practice the only one where have felt the need
On 9/19/06, Jan-Willem Maessen [EMAIL PROTECTED] wrote:
On Sep 18, 2006, at 4:47 AM, Einar Karttunen wrote:
On 18.09 01:23, Josef Svenningsson wrote:
On 9/17/06, Jan-Willem Maessen [EMAIL PROTECTED] wrote:
You can associate a unique name with each traversal, and store a set
of traversals
On 9/17/06, Jan-Willem Maessen [EMAIL PROTECTED] wrote:
On Sep 13, 2006, at 3:37 AM, Einar Karttunen wrote:
Hello
Is there an elegant way of traversing a directed graph in STM?
type Node nt et = TVar (NodeT nt et)
type Edge et= TVar et
data NodeT nt et = NodeT nt [(Node nt et,
Klaus,
You've gotten many fine answers to your question. I have yet another
one which is believe is closest to what you had in mind. The key to
the solution is to add an extra type parameter to Labelled like so:
data Labelled f a = L String (f a)
Now you can use it to form new recursive type
Brian,
You might also want to take a look at the list fusion functionality in
GHC which often can help optimize your programs when programming with
lists.
http://www.haskell.org/ghc/docs/latest/html/users_guide/rewrite-rules.html#id3153234
It doesn't help in your particular program but it might
On 4/5/06, Robert Dockins [EMAIL PROTECTED] wrote:
Hey, if we wanted a private conversation, we'd take it off-list. :-)
:-)
Do you have any reference to the fact that there is any diagreement
about the term? I know it has been used sloppily at times but I think
it is pretty well defined.
On 3/28/06, Neil Mitchell [EMAIL PROTECTED] wrote:
This feels like a situation Parsec users would find themselves in all the
time. When you have a bunch of parsers in a 'choice', does the start of the
input stream linger until the last parser is executed?
No, as soon as one token is
Sorry for the slow reply,On 3/8/06, Einar Karttunen ekarttun@cs.helsinki.fi wrote:
Does anyone have an efficient tree implemented in STM thatsupports concurrent updates in an efficient fashion? Thisseems suprisingly hard to implement - a normal binarytree with links as TVar is very slow and does
On 1/7/06, Chris Kuklewicz [EMAIL PROTECTED] wrote:
When you put print (head p) at then end, it keeps a reference to thewhole list p which is your space leak.If you want to store the headof p, this *should* work: main = do n - getArgs = return . read . head
let p = permutations [1..n] headOfP -
On 10/12/05, John Meacham [EMAIL PROTECTED] wrote:
I certainly think we should somehow centralize an index to papers onhaskell. I have found it extremely difficult to track down papers forauthors that have since moved out of academia or have passed on anddon't have their personal homepages with
On 6/6/05, Dimitry Golubovsky [EMAIL PROTECTED] wrote:
Does there exist a tool which given a Haskell source, shows functions
that are mutually recursive (i. e. call each other, even via calling
third, etc. functions)? Knowledge of that would help to split the
module into smaller modules
On Mon, 14 Feb 2005 19:01:53 -0500, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
I was thinking more along the lines of Ralf Hinze's nondeterminism
transformer monad:
http://haskell.org/hawiki/NonDeterminism
The relevant instance is this:
instance (Monad m) = MonadPlus (NondetT m)
On Sun, 13 Feb 2005 19:08:26 -0500, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
Quoting Josef Svenningsson [EMAIL PROTECTED]:
I think it's unfair to the monad transformers to simply say that they
don't obey the law. The interesting thing is whether they *preserve*
the law. A monad
On Mon, 14 Feb 2005 10:07:41 -0500, Jacques Carette [EMAIL PROTECTED] wrote:
Josef Svenningsson [EMAIL PROTECTED] wrote:
You claimed that monad transformers break the
mzero-is-right-identity-for-bind law because they can be applied to
IO. I say, it's not the monad transformers fault
On Sun, 13 Feb 2005 17:59:57 -0500, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
G'day all.
Quoting Remi Turk [EMAIL PROTECTED]:
According to http://www.haskell.org/hawiki/MonadPlus (see also
the recent thread about MonadPlus) a MonadPlus instance
should obey m mzero === mzero, which IO
On Thu, 09 Dec 2004 10:18:12 -0500, Robert Dockins
[EMAIL PROTECTED] wrote:
And I thought that most programmers used zipWith, which has to be
prefix.
Is this true? Can you not use backticks on a partially applied
function? If so, it seems like such a thing would be pretty useful
On Tue, 30 Nov 2004 18:36:46 + (UTC), Pavel Zolnikov
[EMAIL PROTECTED] wrote:
[..]
type M2 a = OuptutMonadT Maybe String a
whenError:: M2 a - M2 a - M2 a
1 foo a b = do
2 output before
3 let r = liftM2 (+) a b
4 `whenError` $ reportError error
5 return r
Let me just begin by sharing my experience with scoped type variables. I've
found them very useful in a project were I was to generalize a substantial
code base. Many of the functions had local definitions whose type were
simply not expressible without scoped type variables. During this work I
Hi all,
At osdir there is a nice interview with David Roundy about darcs, the
revision control system written in Haskell. He has a few comments about
Haskell as well. Read it here:
http://osdir.com/Article2571.phtml
This was also covered on /. (which is where I found it).
/Josef
It is, of course, trivial to implement this for lists. I've run into
a snag, however, when trying to implement this for Arrays (as in
Data.Array) - I can't seem to find a way to represent an empty array,
which makes implementing 'empty' and 'null' impossible. Suggestions?
Empty arrays can
Andre,
I very much enjoyed reading your blog entry. I would like to make a few
comments.
First of all I heartly agree with what you call the main problem. I
quote: The main problem I see with all this is that its just too hard
for an average Haskell programmer to get good performance out of
On Mon, 29 Mar 2004, Fred Nicolier wrote:
Is there a way to get the number of dimension of an array ? i.e.
something like :
dims :: (Ix a) = Array a b - Int
dims = ...
a = listArray (1,10) [1,2..]
b = listArray ((1,1),(10,10)) [1,2..]
dims a -- should be equal to 1
dims b -- should
Hi,
On Thu, 5 Feb 2004, Ron de Bruijn wrote:
Hi there,
I need a complete 3-CNF-Sat solver that can solve
sentences of about length 20 (or shorter).
Now I use simple model checking, but that's a bit slow
, you understand :)
I have seen some algorithms on the web and some
code-sniplets
OK, this one is just too good not to post about it.
Microsoft has developed a now command line interface. Guess what they call
it? Read it here:
http://slashdot.org/articles/03/10/31/1346201.shtml?tid=185tid=190tid=201
Well, it seems Simoj PJ is doing a good job introducting functional
Sorry about replying to my own mail.
On Mon, 27 Oct 2003, Josef Svenningsson wrote:
On Mon, 27 Oct 2003, Paul Hudak wrote:
Thomas L. Bevan wrote:
Is there a simple transformation that can be applied to all
recursive functions to render them non-recursive with fix.
Suppose you
On Mon, 27 Oct 2003, Paul Hudak wrote:
Thomas L. Bevan wrote:
Is there a simple transformation that can be applied to all
recursive functions to render them non-recursive with fix.
Suppose you have a LET expression with a set of (possibly mutually
recursive) equations such as:
let f1
Hi,
On Mon, 29 Jul 2002, Scott J. wrote:
Can one write withthe Haskell compliler faster code than in the
examples of http://www.bagley.org/~doug/shootout/ where GHC (old
Haskell 98?) seems to be much slower than Ocaml or Mlton both strict
functional languages. Can one expect any
On Thu, 21 Feb 2002, Mark Wotton wrote:
Hi,
I'm trying out some combinatorial parsers, and I ran into a slightly
inelegant construction. To parse a sequence of things, we have a function
like
pThen3 :: (a-b-c-d) - Parser a - Parser b - Parser c - Parser d
pThen3 combine p1 p2 p3 toks =
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