On Mar 18, 2007, at 21:36 , Jeremy Shaw wrote:
Hello,
If you have tried to do any MIME processing using Haskell, you are
likely to have found two things:
1) There are a lot of MIME libraries for Haskell
2) None of them do everything you want
So, I propose that we form a MIME Strike Force
On Mon, Mar 19, 2007 at 05:11:19PM +, Edsko de Vries wrote:
What I'm wondering about is if this monad is an instance of a more
general monad(if so, which one?), and generally if people have any
comments about these definitions.
It's like the Writer monad used with different monoids.
On 20/03/07, Bryan Burgers [EMAIL PROTECTED] wrote:
On the topic of 'fix', is there any good tutorial for fix?
I quite liked this one:
http://dreamsongs.org/Files/WhyOfY.pdf
Alistair
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Matthew Brecknell wrote:
Ivan Miljenovic:
As such, I'd like to know if there's any way of storing a an n-by-n
matrix such that the algorithm/function to get either the rows or the
columns is less than O(n^2) like transposition is. I did try using an
Array, but my (admittedly hurried and
I would also recommend
Mitchell, Machine Learning.
I have quite a lot of Haskell code for stuff in this book, which I'm currently
polishing for publishing. (For example, I'm rather proud of my thirty line
neural network code.)
___
Haskell-Cafe
oops, I realized now that my answer did not go to the list.
For the record here is it:
Thanks to everybody for the answers and to Henning Thielemann for the
useful links:
http://haskell.org/haskellwiki/Qualified_names
http://haskell.org/haskellwiki/Category:Style
I agree with apfelmus
Bulat Ziganshin wrote:
Hello Fawzi,
Monday, March 19, 2007, 8:26:33 PM, you wrote:
Maybe I did not express me clearly enough, I think that classes are
useful (and the language that I was speaking of, aldor, has them), but
it is not nice that the only way to have an overloaded function is
David House wrote:
On 19/03/07, Fawzi Mohamed [EMAIL PROTECTED] wrote:
Vectors don't act like numbers, a vector space is not a field, even if
they have some common operations.
As I said in my previous email, this is because Num is too big. We
need to split it down, but there's no sane way of
Matthew Brecknell wrote:
There is the question of whether it's preferable to use the let form
or the fix form for embedding a recursive function in the middle of a
do-block. I don't know if there's any consensus on this question, but it
seems to me to be about whether one prefers to read a
[left-fold operator for enumerating the lines of a text file]
..
enumLines :: (a - String - Either a a) - a - FilePath - IO a
enumLines iter accum filename = do
h - openFile filename ReadMode
flip fix accum $
\iterate accum - do
try_line - try (hGetLine h)
case try_line of
When you tried using Arrays, I presume you used an array indexed by a
pair (i,j), and just reversed the order of the index pair to switch from
row-wise to column-wise access? It's hard to see how that would slow you
down. Perhaps the slowdown was caused by excessive array copying?
the
This page was sent to you by: [EMAIL PROTECTED]
John Backus, inventor of Fortran, Turing Award winner, and also an early
pioneer in functional programming, died Saturday at his home in Oregon. Many of
us have fond memories of him in the earlier days of our careers, and we all owe
a lot to him
Just thought I'd add another potentially helpful bit to this oneliner
/ shell scripting thread. Though to be fair, this perhaps strains the
definition of one in one liner.
This takes a long file containing mostly numerical data, filters out
the numerical data, and sorts it numerically. (Not the
To answer my own post, the Data.List.sort *is* necessary.
Otherwise, you get alphabetic sort.
2007/3/20, Thomas Hartman [EMAIL PROTECTED]:
Just thought I'd add another potentially helpful bit to this oneliner
/ shell scripting thread. Though to be fair, this perhaps strains the
definition of
Same thing, but with better comments and whitespace.
[EMAIL PROTECTED]:~/learning/haskell/UnixToolshead -n30 sortNumeric.sh
cat out_select_char_length_csv.out | ghc -e '
interact $
unlines
-- take 10 from the end
-- more efficient than
-- reverse . take 10 . reverse
Quoth Thomas Hartman, nevermore,
This takes a long file containing mostly numerical data, filters out
the numerical data, and sorts it numerically. (Not the same thing as
sorting alphabetically, which is what you get by default, or using the
unix sort utility). Maybe there's some flag to make
I've been talking to Chris Eidhof the last days and we'd like to suggest adding
another specialized haskell mailinglist: Haskell and web developement.
I think the global interest will increase in the feature, libraries are
evolving and it would be nice to have a place to discuss them.
Any
You contributed
#12:14 Thunder @pl \s - drop (length s - n) s
#12:14 lambdabot drop = subtract n . length
But, on second thought, 1) I can't use this as a drop-in replacement
for the non points free (right term?) version, and 2) I don't really
understand it.
Still, I would be curious to see
Claus Reinke wrote:
When you tried using Arrays, I presume you used an array indexed by a
pair (i,j), and just reversed the order of the index pair to switch from
row-wise to column-wise access? It's hard to see how that would slow you
down. Perhaps the slowdown was caused by excessive array
Marco Weber wrote:
I've been talking to Chris Eidhof the last days and we'd like to suggest adding
another specialized haskell mailinglist: Haskell and web developement.
I support the idea to have such a mailing list.
Thanks.
--
Dimitry Golubovsky
Anywhere on the Web
* Thomas Hartman wrote:
You contributed
#12:14 Thunder @pl s - drop (length s - n) s
#12:14 lambdabot drop = subtract n . length
But, on second thought, 1) I can't use this as a drop-in replacement
for the non points free (right term?) version, and 2) I don't really
understand it.
I did
Thomas Hartman wrote:
To answer my own post, the Data.List.sort *is* necessary.
Otherwise, you get alphabetic sort.
Which is why you do the Set trick at a different stage in the process,
like this:
interact $
unlines
. map show
-- more efficient than -- reverse . take 10 . reverse
. (
Hello Fawzi,
Tuesday, March 20, 2007, 1:47:48 PM, you wrote:
That was the reason that is spoke of aldor ( http://www.aldor.com ), as
it has type inference, but yes indeed this makes type inference much
more difficult and undefined in some cases (also haskell extensions make
inference in
Hallo list,
I don't quite get how ($!) works. I have this function:
dbCreateIndices con dtn dof = do
let dummy = newDbItem
let query = SELECT id FROM ++ (dtn dummy) ++ ORDER BY ++ (dof dummy)
ids - liftM (map fromSql . concat ) $! quickQuery con query []
return $ IntMap.fromList
Alex Queiroz wrote:
quickQuery returns a lazy list of results, and I expected ($!) to make
it strict. But my program crashes if I use it this way. But, if I add
a print to the function:
'Making things strict' isn't that simple.
What $! does is force its arguments into WHNF before applying the
Hallo,
On 3/20/07, Jules Bean [EMAIL PROTECTED] wrote:
What $! does is force its arguments into WHNF before applying the
function. WHNF means, roughly, either a lambda or a constructor at the
top-level.
I think I got it now.
However that's a bit clumsy. What kind of error are you
Alex Queiroz wrote:
However that's a bit clumsy. What kind of error are you seeing when you
say 'it crashes'?
I must fetch all rows of the result, otherwise the database will
be in an inconsistent state and all subsequent queries crash the
application. Fetching all rows automatically
Bulat Ziganshin wrote:
Hello Fawzi,
Tuesday, March 20, 2007, 1:47:48 PM, you wrote:
That was the reason that is spoke of aldor ( http://www.aldor.com ), as
ehm http://www.aldor.org
it has type inference, but yes indeed this makes type inference much
more difficult and undefined in
On 20/03/07, Marc Weber [EMAIL PROTECTED] wrote:
I've been talking to Chris Eidhof the last days and we'd like to suggest adding
another specialized haskell mailinglist: Haskell and web developement.
I'd love to contribute here. You should be able to find an appropriate
email to ask for this
it seems unlikely to me that this would cause a degradation in
performance with respect to lists...
that might depend on the number of operations per transposition, i guess.
lists and explicit transpositions make it very obvious what is going on in
terms of
iteration order, so i would be
Ivan Miljenovic wrote:
(a primitive Sudoku solver, to be precise)
Concerning Sudoku, there is a beautiful talk from R. Bird
http://icfp06.cs.uchicago.edu/bird-talk.pdf
The other problem with using a list of lists is that the only reason I'm sure
that the matrix is valid (i.e. all the
Alfonso Acosta wrote:
Just in case it helps, I ported the code of Norvigs Paradigms of
Artificial Intelligence Programming chapter 8 (integrals and
derivates) for a collage course.
A link to this code would have been / would still be most appreciated.
Jacques
Edsko de Vries wrote:
Hey,
I have a structure containing Xs in various places, like so
data X
data Structure = Structure .. [X] .. [X] ..
And I defined mapStructure
mapStructure :: (X - X) - (Structure - Structure)
I then wanted to use mapStructure to define queries as well as
Hello,
On my system, GHC 6.6 running on windows xp, System.Time.toClockTime
fails on calendar times later than (by days, I didn't check hours,
minutes, etc.) January 18, 2038. Is this a bug?
thanks,
Jeff
---
This e-mail may contain confidential and/or privileged information. If you
On 3/20/07, Jacques Carette [EMAIL PROTECTED] wrote:
A link to this code would have been / would still be most appreciated.
I would have provided it if I had it, but the code is not online.
However I don't have any problem to send it or uploaded somewhere. Any
suggestions?
Quoth Jeff Polakow, nevermore,
On my system, GHC 6.6 running on windows xp, System.Time.toClockTime
fails on calendar times later than (by days, I didn't check hours,
minutes, etc.) January 18, 2038. Is this a bug?
That *sounds* suspiciously like the Year 2038 problem [1]. I thought it
Alfonso,
Lemmih (from #haskell) has been kind enough to give me space on a
server for a darcs repo. I could add your code there if you'd like to
email it to me, or we could ask him if you could have your own space.
Perhaps you could email me off-list and we can arrange it.
On 3/20/07, Alfonso
Hallo,
On 3/20/07, Jules Bean [EMAIL PROTECTED] wrote:
Personally I'd inclined to suggest use of the strict FetchRow which the
library provides than struggle with explicit uses of seq to fight an
over-lazy IO action.
Sounds like a good suggestion. Thanks very much for the help!
Cheers,
Oleg,
data Name = Name String String deriving Show
newtype Salary = S Float deriving Show
data Dept = D String Int deriving Show
I like the idea of these simpler label declarations, but I think the
cost is that it is harder to write generic code for e.g. parsing
urlencoded data or
i get the following error message
new.o:fake:(.text+0x85): undefined reference to
`parseczm2zi0_TextziParserCombin
atorsziParsecziChar_oneOf_closure'
new.o:fake:(.rodata+0x4): undefined reference to
`parseczm2zi0_TextziParserCombi
natorsziParsecziChar_oneOf_closure'
collect2: ld returned 1 exit
Matthew Brecknell [EMAIL PROTECTED] writes:
enumLines :: (a - String - Either a a) - a - FilePath - IO a
enumLines iter accum filename = do
h - openFile filename ReadMode
flip fix accum $
\iterate accum - do
try_line - try (hGetLine h)
case try_line of
Left e -
On Mar 20, 2007, at 1:23 PM, david karapetyan wrote:
i get the following error message
new.o:fake:(.text+0x85): undefined reference to
`parseczm2zi0_TextziParserCombin
atorsziParsecziChar_oneOf_closure'
Add either the --make parameter or the -package parsec parameter to GHC.
--
brandon
Bulat Ziganshin wrote:
Hello Fawzi,
Tuesday, March 20, 2007, 5:37:45 PM, you wrote:
ambiguous function call at line xxx.
Possible instances are:
f: Int - String - Double - a
f: String - Int - [Int] - a
please explicitly annotate the type to disambiguate
Note that you
At Tue, 20 Mar 2007 12:02:20 -0400,
Jeff Polakow wrote:
[1 multipart/alternative (7bit)]
[1.1 text/plain; US-ASCII (7bit)]
Hello,
On my system, GHC 6.6 running on windows xp, System.Time.toClockTime
fails on calendar times later than (by days, I didn't check hours,
minutes, etc.)
Dan Weston wrote:
Douglas Philips wrote:
On 2007 Mar 20, at 3:30 PM, Dan Weston indited:
I looked up John Backus on wikipedia and followed a link to ALGOL:
http://en.wikipedia.org/wiki/ALGOL_60
where the following undesirable property of call-by-name is mentioned.
ALGOL 60 allowed for two
There is currently a happs mailing list. I see no reason not to
broaden the subject matter to haskell web development in general.
The URL for the list is http://groups.google.com/group/happs
-Alex-
On Tue, 20 Mar 2007, David House wrote:
On 20/03/07, Marc Weber [EMAIL PROTECTED] wrote:
I'm also interested. I'm trying to free up some time to experiment a
bit with web frameworks. I would also like to try help to clean up the
HTTP module and increase its performance.
Johan
On 3/20/07, Marc Weber [EMAIL PROTECTED] wrote:
I've been talking to Chris Eidhof the last days and we'd
On 3/20/07, David House [EMAIL PROTECTED] wrote:
On 20/03/07, Marc Weber [EMAIL PROTECTED] wrote:
I've been talking to Chris Eidhof the last days and we'd like to suggest
adding
another specialized haskell mailinglist: Haskell and web developement.
I'd love to contribute here. You should be
On 3/20/07, Dan Weston [EMAIL PROTECTED] wrote:
Dan Weston wrote:
Douglas Philips wrote:
On 2007 Mar 20, at 3:30 PM, Dan Weston indited:
I looked up John Backus on wikipedia and followed a link to ALGOL:
http://en.wikipedia.org/wiki/ALGOL_60
where the following undesirable property of
Bertram Felgenhauer wrote:
Having to rely on GC to close the fds quickly enough is another problem;
can this be solved on the library side, maybe by performing GCs when
running out of FDs?
Claus Reinke wrote:
in good old Hugs, for instance, we find in function newHandle in
src/iomonad.c
On 21/03/07, apfelmus [EMAIL PROTECTED] wrote:
Concerning Sudoku, there is a beautiful talk from R. Bird
http://icfp06.cs.uchicago.edu/bird-talk.pdf
I based my Latin Squares algorithms on Bird's Functional Pearl article
A Program to play Sudoku
The other problem with using a list of
The nice thing about Haskell's overloading is that every function,
like f, has a type.
Not two different types, but one general type you can give it. It's
a different approach to overloading.
-- Lennart
On Mar 20, 2007, at 14:37 , Fawzi Mohamed wrote:
Bulat Ziganshin wrote:
Jeremy Shaw [EMAIL PROTECTED] writes:
Try using Data.Time instead -- it was written by a self-professed time
nerd, and probably works correctly. It was added in GHC 6.6 and
largely supercedes System.Time.
Curiously, Hoogle doesn't seem to have it indexed yet -- I
was looking for it just the
On Tue, Mar 20, 2007 at 04:04:42PM -0400, S. Alexander Jacobson wrote:
There is currently a happs mailing list. I see no reason not to
broaden the subject matter to haskell web development in general.
The URL for the list is http://groups.google.com/group/happs
-Alex-
Hi Alex
The
Jules Bean:
If you're merely talking about top-down or bottom-up then there is also
'where' rather than 'let'.
Yes, I admit I tend to prefer where over let, all else being equal.
But my main concern was embedding recursive functions in do-blocks,
particularly monadic loops that aren't
On Tue, Mar 20, 2007 at 02:25:41PM +0100, Marc Weber wrote:
I've been talking to Chris Eidhof the last days and we'd like to suggest
adding
another specialized haskell mailinglist: Haskell and web developement.
I've written to John Peterson who replied:
I'm sure that will be fine -
Matthew Brecknell [EMAIL PROTECTED] writes:
Pete Kazmier:
I understand the intent of this code, but I am having a hard time
understanding the implementation, specifically the combination of
'fix', 'flip', and 'interate'. I looked up 'fix' and I'm unsure how
one can call 'flip' on a function
Pete Kazmier:
Haskell has a way of making one feel dumb. This is by far the most
challenging programming language I've ever used.
It (or perhaps the community around it) does have a way of making you
realise that the rabbit-hole really is very deep. But that's no reason
to feel dumb.
I won't
Matthew Brecknell [EMAIL PROTECTED] writes:
As others have pointed out, fix is polymorphic, so a can stand for any
type, including (b - c). Removing redundant parentheses, this means
fix can directly specialise to:
fix :: ((b - c) - b - c) - b - c
I understand now. I think part of my
Haskell has a way of making one feel dumb. This is by far the most
challenging programming language I've ever used.
i wouldn't see either as a particularly positive attribute. a language should
enable,
explain, encourage, and perhaps inspire. if it also leaves you feeling that you
could
do
But in fact it seems to me that the type variable a not only can, but
must unify with b-c.
Is there any use of fix for which this is not true? If this is true, is
the type a instead of b-c because it is not possible in general for
the type checker to verify this fact, making it some kind of
Assuming 1 :: Int, then:
ones = 1 : ones
is equivalent to:
ones = fix (\ones - 1:ones)
where fix has type ([Int] - [Int]) - [Int].
It's also the case that:
inf = 1+inf
is equivalent to:
inf = fix (\inf - 1+inf)
where fix has type (Int - Int) - Int.
Unfortunately (perhaps), the fixed point
In effect, this is a demonstration that Haskell supports recursive
values and not just recursive functions. If the a in
fix :: (a - a) - a
were to be unified always with a function type, then that would imply
that the language only supported recursive definitions for functions,
which would be a
On 3/19/07, Nicolas Frisby [EMAIL PROTECTED] wrote:
Nope, but I believe the two are equipotent. This usage of believe is
one of those I think I remember reading it somewhere usages.
On 3/19/07, Henning Thielemann [EMAIL PROTECTED] wrote:
On Sat, 17 Mar 2007, Nicolas Frisby wrote:
Bekic's
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