Hi cafè,
given the following toy code:
---
module Main where
class Dumb p where
dumb :: p - String
newtype Branded a b = Branded b
unbrand :: Branded a b - b
unbrand (Branded x) = x
wrong :: Dumb a = b - Branded a b
wrong = Branded
right :: Show a = b - Branded a b
right
On Fri, Feb 11, 2011 at 20:00, Daniel Fischer
daniel.is.fisc...@googlemail.com wrote:
...
It's because there's no way to determine the type variable a (in either
wrong or right).
That's what I thought when I wrote the code at first but then I was
surprised to see it working with the Show
Hi all,
I've a type problem that I cannot solve and, before I keep banging my
head against an unbreakable wall, I'd like to discuss it with the
list.
Consider the following code:
module Main where
class PRead p where {}
class PWrite p where {}
newtype Sealed p a = Sealed a
On Wed, Feb 9, 2011 at 18:43, Steffen Schuldenzucker
sschuldenzuc...@uni-bonn.de wrote:
...
let good = appendLog Foo Bar :: Sealed Admin String
unseal (undefined :: Admin) good
FooBar
That's true, but putting apart the problem I posed, in my construction
I wouldn't expose unseal directly nor
On Wed, Feb 9, 2011 at 19:33, Alexey Khudyakov
alexey.sklad...@gmail.com wrote:
...
If Private is not exported one cannot add instances to PRead.
Nice trick. I would have thought of hiding the classes PRead and
PWrite but I'm not sure if it could break the code.
Thank you!
--
Cristiano
GPG
On Wed, Feb 9, 2011 at 20:14, Alexey Khudyakov
alexey.sklad...@gmail.com wrote:
...
My solution is based on heterogenous lists and require number of
language extensions. I'd recomend to read paper Strongly typed
heterogeneous collections[1] which describe this technique in detail
Curious: I
On Wed, Feb 9, 2011 at 20:14, Alexey Khudyakov
alexey.sklad...@gmail.com wrote:
...
instance PRead (WRead ::: b)
instance PRead b = PRead (a ::: b)
instance PWrite (WWrite ::: b)
instance PWrite b = PWrite (a ::: b)
Brilliant! I was thinking to something like this but
Hi all,
I was reading:
http://www.haskell.org/haskellwiki/GHC/AdvancedOverlap
and I became curious. Playing with the code I started to find a way to say:
instance Show a = ShowPred a HTrue
instead of enumerating all the instances, mirroring those of the Show class:
instance ShowPred Int
On Wed, Jan 5, 2011 at 20:35, Stephen Tetley stephen.tet...@gmail.com wrote:
Though its quite different to AdvancedOverlap, Conal Elliott has a
method of answering the title of your post - Choosing a type-class
instance based on the context.
See the CxMonoid (context monoid) in Section 3.
On Fri, Jan 22, 2010 at 11:38 AM, Bayley, Alistair
alistair.bay...@invesco.com wrote:
...
Tried and failed. Our firewall will be closed to port 22 for the
forseaable future. I'll give the OpenVPN thing a go, if I can find some
time.
Trying to ask how to pierce your company's firewall in a
I wish to thank all of you for your comments.
In fact, the solutions you proposed mostly coincided with mine
(including the one using type families) but, in my opinion, they are
more cumbersome than the prefixed names solution.
Going back to my example:
f x = open $ open x
where:
data Foo = {
Hi,
these days I'm thinking about name scoping in Haskell and a question
built up silently but steadily in my mind.
Many times I see code like this:
data Foo = { fooBar :: Int, fooSay :: String, fooClose :: String }
which reminds me of Ye Olde Times of C where you prepend the
structure name
On Sun, Nov 22, 2009 at 3:47 AM, Felipe Lessa felipe.le...@gmail.com wrote:
...
Well, “ReaderT XConf (StateT XState IO) a” is *the* type :).
It's a monad that is a Reader of XConf and has a State of XState.
... and also wraps a monad to allow IO access inside the X monad.
Cristiano
On Mon, Nov 16, 2009 at 6:26 PM, Gwern Branwen gwe...@gmail.com wrote:
...
Too late:
...
http://hackage.haskell.org/package/loli
What's the point with loli?
Cristiano
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
On Thu, Oct 8, 2009 at 11:04 AM, minh thu not...@gmail.com wrote:
Hi,
I'd like to know what are the typing rules used in Haskell (98 is ok).
Specifically, I'd like to know what makes
let i = \x - x in (i True, i 1)
legal, and not
let a = 1 in (a + (1 :: Int), a + (1.0 :: Float))
Is it
On Thu, Oct 8, 2009 at 12:48 PM, Lennart Augustsson
lenn...@augustsson.net wrote:
The reason a gets a single type is the monomorphism restriction (read
the report).
Using NoMonomorphismRestriction your example with a works fine.
Could you explain why, under NoMonomorphismRestriction, this
On Sat, Sep 19, 2009 at 6:53 PM, Ben Franksen ben.frank...@online.de wrote:
Cristiano Paris wrote:
Daniel Fischer wrote:
I would separate the reading of headers and bodies, reopening the files
whose body is needed, for some (maybe compelling) reason he wants to do
it differently.
Yes
On Fri, Sep 18, 2009 at 4:06 AM, Ryan Ingram ryani.s...@gmail.com wrote:
I am confused about why this thread is talking about unsafePerformIO at
all. It seems like everything you all want to do can be accomplished with
the much less evil unsafeInterleaveIO instead. (Which is still a bit evil;
On Fri, Sep 18, 2009 at 5:15 AM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
...
But that does something completely different from what Cristiano wants to do.
He wants to read many files files quasi-parallel.
As far as I can tell, he needs to read a small chunk from the beginning of
every
I wish to thank Cafè's people for their great support in understanding Haskell.
Thank you all!
Cristiano
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
On Thu, Sep 17, 2009 at 8:36 AM, Ryan Ingram ryani.s...@gmail.com wrote:
...
Explicitly:
Haskell:
test1 :: forall a. a - Int
test1 _ = 1
test2 :: (forall a. a) - Int
test2 x = x
explicitly in System F:
test1 = /\a \(x :: a). 1
test2 = \(x :: forall a. a). x @Int
/\ is type-level
On Tue, Sep 15, 2009 at 11:31 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
...
Yeah, you do *not* want the whole file to be read here, except above for
testing purposes.
That's not true. Sometimes I want to, sometimes don't. But I want to
use the same code for reading files and exploit
On Thu, Sep 17, 2009 at 10:01 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
...
readBit fn = do
txt - readFile fn
let (l,_:bdy) = span (/= '\n') txt
return $ Bit (read l) bdy
?
With
main = do
args - getArgs
let n = case args of
(a:_) - read a
On Tue, Sep 15, 2009 at 11:38 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
...
foo :: forall a. a - a
This is exactly the same type as
foo :: a - a
(unless you're using ScopedTypeVariables and there's a type variable a in
scope), since
type signatures are implicitly forall'd.
On Wed, Sep 16, 2009 at 7:12 PM, Ryan Ingram ryani.s...@gmail.com wrote:
Here's the difference between these two types:
test1 :: forall a. a - Int
-- The caller of test1 determines the type for test1
test2 :: (forall a. a) - Int
-- The internals of test2 determines what type, or types, to
Hi Cafè,
I've the following problem: I have a (possibly very long) list of
files on disk. Each file contains some metadata at the beginning and
continues with a (possibly very large) chunk of data.
Now, the program I'm writing can be run in two modes: either read a
specific file from the disk
On Tue, Sep 15, 2009 at 9:13 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
...
Still, the body should be read lazily.
I'm not sure, but the tracing message may be output because of its position.
With
where
readBody = withFile fn ReadMode $ \h - do
b - hGetContents h
On Tue, Sep 15, 2009 at 9:16 PM, Svein Ove Aas svein@aas.no wrote:
I have a number of suggestions, some of which conflict with each
other, so I'll just throw them out here. Let's see..
:)
First off, the IO monad does indeed enforce sequencing; that's its
primary purpose.
So,
On Tue, Sep 15, 2009 at 9:39 PM, Svein Ove Aas svein@aas.no wrote:
As a general sort of warning, do not use hGetContents (or lazy i/o, in
general) in combination with withFile.
withFile closes the handle when the program lexically exits its scope.
However, when using hGetContents, the
On Tue, Sep 15, 2009 at 10:12 PM, Ross Mellgren rmm-hask...@z.odi.ac wrote:
Wouldn't seq b only force (at minimum) the first character of the file?
I think it force the evaluation of the Cons in the String but not
the characters therein.
Cristiano
___
On Tue, Sep 15, 2009 at 10:11 PM, Cristiano Paris fr...@theshire.org wrote:
On Tue, Sep 15, 2009 at 10:08 PM, Cristiano Paris fr...@theshire.org wrote:
...
So, it seems that seq b is completely ineffective and program is not
correct.
Correction: removing seq b results in nothing being
On Tue, Sep 15, 2009 at 10:20 PM, Ross Mellgren rmm-hask...@z.odi.ac wrote:
Ack, IGNORE ME! Way too strict.
Oh, well, I used foldr+seq to achieve the same result... I think, but
I think that, if this is the solution, I'll use rnf as I did on other
occasions.
Thanks.
Cristiano
On Tue, Sep 15, 2009 at 10:25 PM, Cristiano Paris fr...@theshire.org wrote:
...
Two points:
1 - I had to cut off file1.txt to be just above 1024 bytes otherwise
the program becomes extremely slow even on a 100KB file with a line
being output every 5 seconds and with my CPU being completely
On Tue, Sep 15, 2009 at 10:08 PM, Cristiano Paris fr...@theshire.org wrote:
...
So, it seems that seq b is completely ineffective and program is not
correct.
Correction: removing seq b results in nothing being displayed :)
So, it's not completely effective. I suspect this is related
On Tue, Sep 15, 2009 at 9:29 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
Am Dienstag 15 September 2009 21:13:02 schrieb Daniel Fischer:
Still, the body should be read lazily.
I'm not sure, but the tracing message may be output because of its
position.
With
where
readBody =
On Tue, Sep 15, 2009 at 10:29 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
...
It evaluates the String far enough to know whether it's or (_:_), that is,
to weak head
normal form. It doesn't look at any character, but it forces at least one
character to be
read from the file.
Yep,
On Tue, Sep 15, 2009 at 10:42 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
Aaawww.
let b' = length b
or
let b' = foldl' seq () b
or
let b' = b `using` rnf
if you want to force the whole file to be read. But then you should
definitely be using
ByteStrings.
Yep. But that
On Wed, Sep 2, 2009 at 7:16 AM, zaxis z_a...@163.com wrote:
Isnot it clear without the 'forall' ?
data Branch tok st a = Branch (PermParser tok st (b - a)) (GenParser tok st
b)
thanks!
I elaborated on this and I wish to add my personal way of figuring out
what the forall keyword means.
On Wed, Sep 2, 2009 at 11:00 AM, zaxisz_a...@163.com wrote:
seems a bit understanding, i still need to think it for a while
thanks!
I think I've understood the existential types thing, but I still can't
put them to work when I think to a solution for a particular problem,
i.e. it's not among
On Tue, Aug 25, 2009 at 12:07 AM, Ryan Ingramryani.s...@gmail.com wrote:
unsafeCoerce is ugly and I wouldn't count on that working properly.
Here's a real solution:
{-# LANGUAGE GADTs, RankNTypes, TypeFamilies, ScopedTypeVariables,
FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
On Tue, Aug 25, 2009 at 7:15 PM, Ryan Ingramryani.s...@gmail.com wrote:
On Tue, Aug 25, 2009 at 6:07 AM, Cristiano Parisfr...@theshire.org wrote:
On Tue, Aug 25, 2009 at 12:07 AM, Ryan Ingramryani.s...@gmail.com wrote:
{-# LANGUAGE GADTs, RankNTypes, TypeFamilies, ScopedTypeVariables,
Thank you all for your answers and sorry for the delay I'm writing
this message but before replying, I wanted to be sure to understand
your arguments!
Now, I'm starting to get into this tying the knot thing and
understand why the Haskell version of fib ties the knot while my
Python version does
On Fri, Jul 17, 2009 at 12:46 PM, Thomas Davietom.da...@gmail.com wrote:
Memoization is not a feature of lazyness. If you can do it in such a way
that you don't waste significant amount of RAM, then it may be a nice
optimisation, and an alternative evaluation strategy, but it would not be
On Fri, Jul 17, 2009 at 12:41 PM, Cristiano Parisfr...@theshire.org wrote:
...
Now, to confirm my hypothesis, I wrote a slight different version of
fib, like follows:
fib' n = 1:1:(fib' n) `plus` (tail $ fib' n) where plus = zipWith (+)
i.e. I inserted a fictious argument n in the
Hi,
as pointed out in this list, it seems that a tying the knot example
would be the one better explaining the power of Haskell's
lazy-by-default approach against Python+Iterator's approach to
laziness.
So, in these days I'm trying to grasp the meaning of this tying the
knot concept which seems
On Tue, Jul 14, 2009 at 3:42 PM, Thomas Davietom.da...@gmail.com wrote:
On 14 Jul 2009, at 15:30, Patai Gergely wrote:
Hello all,
I was asked to give a one-hour 'introductory' seminar on Haskell. The
audience is a bunch of very clever people with a wider than usual
perspective on
2009/7/14 Patai Gergely patai_gerg...@fastmail.fm:
Hello all,
I was asked to give a one-hour 'introductory' seminar on Haskell. The
audience is a bunch of very clever people with a wider than usual
perspective on programming and mathematics, and my talk should be rather
informational than
On Tue, Jul 14, 2009 at 4:46 PM, Bulat
Ziganshinbulat.zigans...@gmail.com wrote:
...
the question is how to justify this in 1 hour. technical people don't
buy such arguments with justification. but if it will be done, it
would be best presentation possible
I think it's important to elaborate
On Tue, Jul 14, 2009 at 5:12 PM, Cristiano Parisfr...@theshire.org wrote:
...
Why don't we create a specific Wiki page about Haskell advocation,
http://haskell.org/haskellwiki/Advocation
Cristiano
___
Haskell-Cafe mailing list
2009/7/9 Marcin Kosiba marcin.kos...@gmail.com:
On Thursday 09 July 2009, Cristiano Paris wrote:
Thanks. In fact, I was stuck trying to find an example which couldn't
be written using Python's iterators. The only difference coming up to
my mind was that Haskell's lists are a more natural way
On Fri, Jul 10, 2009 at 10:35 AM, Wolfgang
Jeltschg9ks1...@acme.softbase.org wrote:
...
Hello Cristiano,
I fear that this instance doesn’t satisfy required laws. As far as I know, the
following equalities should hold:
(*) = ()
f * empty = empty
empty | g = g
This implies the
Hi,
I'm wondering what a good example of why laziness enhances composability
would be.
I'm specifically looking for something that can't implemented in Python with
iterators (at least not elegantly), but can actually be implemented in
Haskell.
Thanks,
Cristiano
Thank you for your suggestions!
C.
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
As a joke, I wrote an instance of Alternative for IO actions:
{-# LANGUAGE ScopedTypeVariables #-}
module Main where
import Control.Applicative
import Control.Exception
instance Alternative IO where
empty = undefined
x | y = handle (\ (_ :: SomeException) - y) x
This would allow to write IO
On Thu, Jul 9, 2009 at 3:42 PM, Edward Kmett ekm...@gmail.com wrote:
Hrmm. This should probably be made consistent with the MonadPlus instance
for IO, so
empty = ioError (userError mzero)
I agree. Of course, that was only a first attempt :)
Cristiano
On Thu, Jul 9, 2009 at 3:42 PM, Bulat Ziganshin
bulat.zigans...@gmail.com wrote:
Hello Cristiano,
Thursday, July 9, 2009, 4:55:09 PM, you wrote:
the best known example is chessmate implementation in Wadler's why
functional programming matter
but i don't know much about Python iterators,
On Wed, May 27, 2009 at 7:14 PM, Manu Gupta manugu...@gmail.com wrote:
Dear anyone,
I wish to learn HASKELL.
That's good for you.
However my institution does not teach it so plus
I don't have a clue how to get around with it. Everything seems so
unconventional and out of place
I know that
On Wed, Apr 22, 2009 at 2:49 AM, michael rice nowg...@yahoo.com wrote:
How do I get the x out of Just x?
Hi Michael,
in your code you're using Maybe to inform the caller of safeDivision
about an exceptional situation. This way, you made a full coverage of
all the input cases and nothing is left
On Tue, Apr 14, 2009 at 4:54 PM, rodrigo.bonifacio
rodrigo.bonifa...@uol.com.br wrote:
Dear Sirs,
I guess this is a very simple question. How can I convert IO [XmlTree] to
just a list of XmlTree?
Quick and dirty answer: unsafePerformIO.
That's an easy finding on Hoogle:
On Tue, Apr 14, 2009 at 5:01 PM, Luke Palmer lrpal...@gmail.com wrote:
...
This is very important: you cannot.
I'd answer You shouldn't, unless you know what you are doing. In
some cases, not only is unsafePerformIO desirable but also necessary
(I'm thinking of Debug.Trace).
Cristiano
On Tue, Apr 14, 2009 at 5:09 PM, Luke Palmer lrpal...@gmail.com wrote:
...
Please don't say that. He's a beginner.
You realize that the path of least resistance will be to use it, right?
You see why that's not a good thing?
Even experts don't use this function.
(To the O.P.: don't use it)
On Tue, Apr 14, 2009 at 5:42 PM, Luke Palmer lrpal...@gmail.com wrote:
...
However, the way I see it is that unsafePerformIO *is* evil by itself, and
it is only by the addition of Holy Water that it is benign to use.
That's what I meant but your words are indeed more effective :)
Ryan
On Tue, Apr 14, 2009 at 5:54 PM, Jules Bean ju...@jellybean.co.uk wrote:
...
I'm convinced about what you say and perhaps I answered the way I did
just because I'm convinced that, for a newbie, knowing about the
existence of unsafePerformIO can't cause any harm.
I was a bit surprised by the
On Tue, Apr 7, 2009 at 3:31 PM, Neil Mitchell ndmitch...@gmail.com wrote:
I was implementing full package support last weekend. With any luck,
I'll manage to push the changes tonight. If not, I'll push them as
soon as I get back from holiday (a week or so)
Thank you, Neil.
Cristiano
On Sat, Apr 4, 2009 at 10:28 PM, Don Stewart d...@galois.com wrote:
cristiano.paris:
...
Isn't this the goal of the process package?
Hi Don,
thank you for the reference. I saw System.Process but when I needed it
I was in a hurry and having a UNIX background I googled for some
snippet
Is it me or the above package is not included in Hoogle?
Cristiano
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
On Sat, Apr 4, 2009 at 10:21 PM, Bulat Ziganshin
bulat.zigans...@gmail.com wrote:
Hello Cristiano,
...
there was a large thread a few months ago and many peoples voted for
excluding any OS-specific packages at all since this decreases
portability of code developed by Hoogle users :)))
Nice
On Mon, Mar 30, 2009 at 9:46 PM, Gü?nther Schmidt gue.schm...@web.de wrote:
Thanks Don,
I followed some examples but have not yet seen anything that would show me
how, for instance, turn a nested Map like
Map Int (Map Int (Map String Double)
into a zipped version.
That is presuming of
On Tue, Mar 31, 2009 at 10:13 PM, Dan Weston weston...@imageworks.com wrote:
What I've learned: Zippers are structured collections[1] with a
focus. Through a Zipper you can O(1) change the value of the focused
element: that's the fundamental property. In addition, you can change
the focus
2009/3/20 Mark Spezzano mark.spezz...@chariot.net.au:
Hi,
I’ve been thinking of changing over to an iMac from my crappy old PC running
Windows Vista.
Question: Does the iMac have good support for Haskell development?
Question: What environment setups do people commonly use (e.g. Eclipse
On Fri, Mar 13, 2009 at 1:19 AM, ChrisK hask...@list.mightyreason.com wrote:
At the cost of writing your own routine you get exactly what you want in a
screen or less of code, see
http://hackage.haskell.org/packages/archive/regex-compat/0.92/doc/html/src/Text-Regex.html#subRegex
for
2009/3/13 Marcin Kosiba marcin.kos...@gmail.com:
...
Threading the state is not the problem. Maybe this will help:
what I have now:
fsm world state = case state of
first -
do_stuff_one
(move_up, succ state)
second -
do_stuff_two
(move_left, succ state)
third -
2009/3/13 Marcin Kosiba marcin.kos...@gmail.com:
Hi,
I've already checked those out. I tried using your yield
implementation and
while it works, I couldn't get it to work with the state monad.
So while:
data RecPair a b = Nil | RP (b, a - RecPair a b)
yield x = Cont $ \k - RP
On 3/5/09, Ryan Ingram ryani.s...@gmail.com wrote:
...
Here is the problem with your update:
tree = Fork (Leaf 1) (Leaf 2)
ztree = initZ tree
test = fromJust $ do
z1 - moveLeft ztree
let z2 = update z1 3
z3 - moveUp z2
z4 - moveLeft z3
this z4
I'd expect test to equal
On Thu, Mar 5, 2009 at 11:21 AM, Heinrich Apfelmus
apfel...@quantentunnel.de wrote:
...
Such self-reference is usually called tying the knot, see also
http://www.haskell.org/haskellwiki/Tying_the_Knot
I didn't know. Would you call this Tying the knot as well?
On Wed, Mar 4, 2009 at 12:50 PM, Heinrich Apfelmus
apfel...@quantentunnel.de wrote:
...
The unusual thing about your implementation is probably that you're
tying a knot by making both moveUp and moveLeft record fields. This
reminds me of
Weaving a web. Ralf Hinze and Johan Jeuring.
On Wed, Mar 4, 2009 at 9:53 PM, Cristiano Paris fr...@theshire.org wrote:
...
Thank you for any further comments.
I forgot to mention one drawback I found in my implementation: it
can't be (de)serialized to a String, which is clearly possible with
Huet's. I think this accounts for the Zipper
Hi,
I'm trying to catch the connection between delimited continuations and
zippers so I wrote a (kinda) zipper interface to a simple tree
structure. Here's the code:
---
module Main where
import Data.Maybe
data Tree a = Leaf a | Fork (Tree a) (Tree a) deriving Show
tree = Fork (Fork (Leaf
On Fri, Feb 27, 2009 at 9:53 PM, Achim Schneider bars...@web.de wrote:
...
In general, just try the maintainer and/or author adresses given on
hsc2hs's hackage page.
Ok, thanks. I suggest to add a comment section to every package's area
in the HackageDB so as to let users report errors, info
Cabalising hsc2hc I get (this is actually from manually building the package):
---
[pa...@bagend hsc2hs-0.67.20061107]$ runghc Setup.hs build
Preprocessing executables for hsc2hs-0.67.20061107...
Building hsc2hs-0.67.20061107...
Main.hs:32:7:
Could not find module `System.Process':
it
On Fri, Feb 27, 2009 at 3:19 PM, Daniel Fischer
daniel.is.fisc...@web.de wrote:
Cabal hides all packages not listed among the build-depends when building the
libraries. I think in 2006, System.Process was in the base package ('twas
before the base-split), so process is not listed among the
On Thu, Feb 26, 2009 at 2:31 AM, Manuel M T Chakravarty
c...@cse.unsw.edu.au wrote:
I'm planning to purchase a MacBookPro so I'm wondering how well
Haskell is supported under this platform.
At least two of the regular contributors to GHC work on Macs. That should
ensure that Mac OS X is well
Hi,
I'm planning to purchase a MacBookPro so I'm wondering how well
Haskell is supported under this platform.
Thanks,
Cristiano
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
2009/2/18 Luke Palmer lrpal...@gmail.com:
...
Using dependent types, you could have Prime come with a proof that the
integer it contains is prime, and thus make those assumptions explicit and
usable in the implementation. Unfortunately, it would be a major pain in
the ass to do that in
On Wed, Feb 18, 2009 at 10:50 AM, Lennart Augustsson
lenn...@augustsson.net wrote:
I just want to make one thing clear. With a type that just contains
prime numbers the onus is on you (the programmer) to provide the proof
that a number is a prime number whenever you claim it is. So you have
On Sat, Feb 14, 2009 at 2:04 AM, Brandon S. Allbery KF8NH
allb...@ece.cmu.edu wrote:
liftIO is defined there, I believe. Many of the monad modules re-export it
with their MonadTrans definitions, but apparently Control.Monad.CC doesn't
so you need to go to the source.
Yeah, I knew the answer
On Fri, Feb 13, 2009 at 2:05 AM, Chung-chieh Shan
ccs...@post.harvard.edu wrote:
...
It's not unheard of for the scheduler to react in different ways to the
same system call -- I'm thinking of reading from a file, for example.
Sure, I went implementing something slitghtly different to double
On Wed, Feb 11, 2009 at 6:41 PM, Achim Schneider bars...@web.de wrote:
...
I got curious and made two pages point to each other, resulting in as
many stale continuations as your left mouse button would permit. While
the model certainly is cool, I'm not aware of any implementation that
even
Hi,
I'm experimenting with delimited continuations in the effort to
understand how they work and when it's convenient to use them.
Consider this piece of code (install the CC-delcont before running it):
{-# LANGUAGE NoMonomorphismRestriction #-}
import Control.Monad.CC
import
I wonder whether this can be done in Haskell (see muleherd's comment):
http://www.reddit.com/r/programming/comments/7wi7s/how_continuationbased_web_frameworks_work/
Cristiano
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
On Wed, Feb 11, 2009 at 2:30 PM, Peter Verswyvelen bugf...@gmail.com wrote:
I haven't looked at the details, but I think this is what a library like
Reactive from Conal Elliott could do, but as far as I understand it, it is
still work in progress.
I'm interested in the possibility of
On Wed, Feb 11, 2009 at 2:53 PM, Sebastian Sylvan
syl...@student.chalmers.se wrote:
I think that would be difficult. You could probably store the continuation
in a server-side cache if you aren't doing CGI but have a persistent server
process, but eventually you'll need to discard unused
On Wed, Feb 11, 2009 at 4:08 PM, Manlio Perillo
manlio_peri...@libero.it wrote:
Cristiano Paris ha scritto:
On Wed, Feb 11, 2009 at 2:30 PM, Peter Verswyvelen bugf...@gmail.com
wrote:
I haven't looked at the details, but I think this is what a library like
Reactive from Conal Elliott could
2009/1/27 Matthijs Kooijman matth...@stdin.nl
Hi all,
I've been reading the gentle introduction to Haskell a bit more closely today
and there a few things which I can't quite understand (presumably because they
are typo's). I've found two issues with the Using monads section [1]. Not
sure
On Tue, Jan 27, 2009 at 3:17 PM, Matthijs Kooijman matth...@stdin.nl wrote:
Hi Cristiano,
Mmmmhhh... this seems the signature of the liftM function, whose
purpose is to make a function operate on monadic values instead of
pure values. Notice that this is different from the lift function
you
On Thu, Jan 8, 2009 at 12:32 AM, Austin Seipp mad@gmail.com wrote:
Excerpts from Immanuel Litzroth's message of Wed Jan 07 16:53:30 -0600 2009:
...
I am little amazed that I cannot get catch, try or mapException to work
without telling them which exceptions I want to catch.
What is the
On Thu, Jan 8, 2009 at 6:04 PM, Jeff Heard jefferson.r.he...@gmail.com wrote:
...
How do I declare all Regions to be Eqs without putting it in the class
body (since I define a function over all Regions that is independent
of datatype that is an instance of Region)?
Would this be a solution?
On Tue, Dec 30, 2008 at 8:35 AM, Conal Elliott co...@conal.net wrote:
Everything in Haskell is a function [...]
Where did this idea come from?
I'd say every expression in Haskell denotes a pure value, only some of which
are functions (have type a-b for some types a b).
Maybe more formally
On Fri, Jan 2, 2009 at 8:53 PM, Conal Elliott co...@conal.net wrote:
I have some speculations:
* In pure OO programming, everything is an object, so in pure functional
programming, one might assume everything is a function. I find the term
value-oriented programming a more accurate label
On Fri, Jan 2, 2009 at 9:21 PM, Miguel Mitrofanov miguelim...@yandex.ru wrote:
module Element where
import QName
import ...
data Element = Element {name :: QName, attribs :: [Attr], content ::
[Content], line :: Maybe Line}
module Attr where
import QName
import ...
data Attr = Attr {key
1 - 100 of 106 matches
Mail list logo
