I've often seen it referred to as the base functor for a recursive data
type. You can then fix that functor in interesting ways i.e. with (Fix,
Free, Cofree) and having the explicit base functor allows you to define
general purpose recursion schemes over the data type. All of that extra
machinery
Anton van Straaten wrote:
On the plus side, this does make for a slogan with high market appeal:
Haskell: Kittens inside
Thanks. Now I have trouble getting this image of lambda-shaped bonsai
kittens out of my head.
;-)
Martijn.
___
ssqHitNum.txt contains data as below:
6 7 18 24 30 32 9
4 12 20 25 28 29 16
3 5 11 12 31 32 11
2 9 13 15 19 24 3
5 17 21 25 27 32 14
5 9 15 21 26 31 13
12 16 25 26 27 31 05
...
good_ssq_red:: IO [Int]
good_ssq_red = withFile ssqHitNum.txt ReadMode (\h - do {
samp - fmap str2Ints $
You may enjoy this interesting blog post by Bartosz Milewski about
understanding C++ template metaprogramming by starting with Haskell.
http://bartoszmilewski.wordpress.com/2009/10/21/what-does-haskell-have-to-do-with-c/
Bartosz gave the talk at the Northwest C++ users group; the video for the
Hello zaxis,
Friday, October 23, 2009, 11:15:01 AM, you wrote:
good_ssq_red = withFile ssqHitNum.txt ReadMode (\h - do {
samp - fmap str2Ints $ hGetContents h;
print samp;--without this line, the result will always [1..16]
return $ statis samp;
})
withFile
Bas van Dijk wrote:
1) What's the difference between your:
tail ~(Cons _ xs) = xs
and the more simple:
tailStrict (Cons _ xs) = xs ?
I know they're desugared to:
tail ys = let Cons _ xs = ys in xs
and:
tailStrict ys = case ys of Cons _ xs - xs respectively.
But aren't they
good_ssq_red:: IO [Int]
good_ssq_red =do {
samp - fmap str2Ints $ readFile ssqHitNum.txt;
return $ statis samp;
}
It works now ! thank you
Bulat Ziganshin-2 wrote:
Hello zaxis,
Friday, October 23, 2009, 11:15:01 AM, you wrote:
good_ssq_red = withFile ssqHitNum.txt ReadMode
Hello zaxis,
Friday, October 23, 2009, 12:02:57 PM, you wrote:
btw,
good_ssq_red = fmap (statis.str2Ints) $ readFile ssqHitNum.txt
or
good_ssq_red = (statis.str2Ints) `fmap` readFile ssqHitNum.txt
good_ssq_red:: IO [Int]
good_ssq_red =do {
samp - fmap str2Ints $ readFile
Paul Johnson wrote:
Paul Johnson wrote:
takeLargest k = take k . sort
Because sort is lazily evaluated this only does enough sorting to
find the first k elements. I guess the complexity is something like
O(n*k*log(k)).
Correction: O(n*log(k))
It's O(n + k log k) (which is the same
Or
good_ssq_red = readFile ssqHitNum.txt = return . statis . str2Ints
I personally prefer this because I like how the = illustrates that
the result is being fed into return . statis . str2Ints, but it is a
matter of style. :-)
Cheers,
Greg
On Oct 23, 2009, at 1:09 AM, Bulat Ziganshin
Hi,
As we know, CST could mean both +8 or -6 time zone. So I got a problem.
In the same envoironment. When a ZonedTime is shown, I got x
CST. Now it means +8 time zone. Then I read it, stupidly, it turns
into -6 time zone.
How could I fix this? I am using ghc 6.10.4 in rhel 5.
--
Thanks for all the pointers, guys. You've been very helpful.
I also found Type-indexed data types (Hinze et al) to be a good source.
Much appreciated!
Martijn.
Martijn van Steenbergen wrote:
data ExprF r
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1) What's the difference between your:
tail ~(Cons _ xs) = xs
and the more simple:
tailStrict (Cons _ xs) = xs ?
I'm no expert - but I can't think of any difference at all.
2) Why don't you also use an irrefutable pattern in take? take is
now defined as:
This is a trickier question: should
Hello.
I have made a simple test.hs file that imports the module QuickCheck.
However, when I load this module in ghci, it says that the module QuickCheck
is not found. I have looked in my haskell platform folder and find the
folder QuickCheck 1.2.0.0.
I also tried to :set -package QuickCheck.
What's wrong?
The package is called QuickCheck. The package consists of a number
of modules. The main module is called Test.QuickCheck.
So
import Test.QuickCheck
should bring all relevant symbols in scope.
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On Tue, 2009-10-13 at 08:48 -0500, John Goerzen wrote:
Now I'm getting complaints from people using 6.10.4 saying that there
are now missing instances of Typeable with time 1.1.2.4.
Right, because 1.1.2.4 is an earlier version than 1.1.3 which is the
random intermediate snapshot version
Nice article from Bartosz , thanks for sharing this.
The best comment (and oh so true IMO) on his article is:
I agree, however, a little more familiarity than that may result in
the desire never to see another line of C++ again, so you have to be
careful.
Although learning Haskell improved my
Andy Stewart lazycat.mana...@gmail.com writes:
Hi all,
Okay, question is, IORefObject module and most module reference each
other, so i will got `recursive reference problem` (looks how many
.hs-boot in my project).
Current version compile fine.
The key is design of IORefObject, It's too
Fellow Haskelleers,
I'm pleased to announce the release of haskell-src-exts-1.2.0!
* On hackage: http://hackage.haskell.org/package/haskell-src-exts
* Via cabal: cabal install haskell-src-exts
* Darcs repo: http://code.haskell.org/haskell-src-exts
Version 1.2.0 is a new major release, following
* On hackage: http://hackage.haskell.org/package/haskell-src-exts
* Via cabal: cabal install haskell-src-exts
Actually, it seems something went awry. I got a 500 Internal Server
Error on my cabal upload, the package is there on hackage but it seems
it was never added to the list of packages.
Maciej Kotowicz asked about implementing binomial heaps using types to
enforce the shape invariants. I dug up an old email from 1998 talking
about how to do this with nested types, and posted it to my blog:
http://okasaki.blogspot.com/2009/10/binomial-queues-as-nested-type.html
-- Chris
I'm happy to announce PastePipe (v1.3)!
PastePipe reads from stdin and publishes whatever it reads to the
hpaste instance of your choice (defaulting to hpaste.org). This makes
it trivial to.
* post a file to hpaste.org: `cat file | pastepipe'
* turn a terminal into a pastebin
Niklas Broberg wrote:
Actually, it seems something went awry. I got a 500 Internal Server
Error on my cabal upload, the package is there on hackage but it seems
it was never added to the list of packages. This means cabal update
doesn't know about it, nor is it listed on the What's New page.
Günther
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Nothing by itself. It's just a definable constructor of some sort.
- Jake
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gue.schmidt:
Günther
Usually it is a strict product. It's just a type constructor of some sort though
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Haskell Weekly News
http://sequence.complete.org/hwn/20091024
Issue 136 - October 24, 2009
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Welcome to issue 136 of HWN, a newsletter covering
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