Il Fri, Sep 01, 2006 at 07:22:02AM +0200, Tomasz Zielonka ebbe a scrivere:
> On Fri, Sep 01, 2006 at 01:13:14AM +0200, Benjamin Franksen wrote:
> > So getting the value out of the monad is not a pure function (extract ::
> > Monad m => m a -> a). I think I stated that, already, in my previous post.
Hello Andrea,
Thursday, August 31, 2006, 4:22:49 PM, you wrote:
> The tutorial will have this outline: first we build a monad adding
> output, exception, and state. Then we use monad transformer to take
> out state and output and add debug, doing lifting, put(ing) and
> get(ing) by hand, to under
Hello Benjamin,
Thursday, August 31, 2006, 9:23:55 PM, you wrote:
> The background for my question is an argument I had some time ago with
> someone about what the 'real nature' of monads is. He argued that monads
> are mainly about 'chaining' (somehow wrapped up) values in an associative
> way,
Hello Benjamin,
Friday, September 1, 2006, 3:13:14 AM, you wrote:
> The real question (the one that bugs me, anyway) is if one can give a
> precise meaning to the informal argument that if the definition of bind is
> to be non-trivial then its second argument must be applied to some
> non-trivial
Il Fri, Sep 01, 2006 at 10:43:14AM +0400, Bulat Ziganshin ebbe a scrivere:
> > The tutorial will have this outline: first we build a monad adding
> > output, exception, and state. Then we use monad transformer to take
> > out state and output and add debug, doing lifting, put(ing) and
> > get(ing)
On Thu, Aug 31, 2006 at 11:09:07AM +0400, Bulat Ziganshin wrote:
> Hello Benjamin,
>
> Wednesday, August 30, 2006, 11:40:09 PM, you wrote:
>
> > Matthias Fischmann wrote:
> >> The trick is that Int is not the only index data type, but tuples of
> >> index data types are, too. Do this:
> >>
> >>
Benjamin Franksen wrote:
Tomasz Zielonka wrote:
whatever you do, you won't be able to extract an 'a' typed
value, non-bottom from this computation. Cont is defined as:
newtype Cont r a = Cont {runCont :: (a -> r) -> r)}
So getting the value out of the monad is not
On Fri, Sep 01, 2006 at 07:22:02AM +0200, Tomasz Zielonka wrote:
> > The real question (the one that bugs me, anyway) is if one can give a
> > precise meaning to the informal argument that if the definition of bind is
> > to be non-trivial then its second argument must be applied to some
> > non-tr
Hello,
The company I work for [1] develops highly sensitive trace gas detectors. We
also develop software that is used to control these detectors from a PC or
laptop. With this software a user can setup an experiment, execute it and
analyse and visualise the data in real-time. While executing,
Hi
1) I would like to know if its difficult to use wxHaskell and STM side by side
and if there are any issues I need to know about.
I have no idea about wxHaskell and STM, but I found out that hard way
that Gtk2Hs + threads = bad idea. Depending on the machine I used, I
got a wide class of un
Hello,
I was just doing Exercise 7.1 of Hal Daumé's very good "Yet Another
Haskell Tutorial". It consists of 5 short functions which are to be
converted into point-free style (if possible).
It's insightful and after some thinking I've been able to come up with
solutions that make me understa
Julien Oster wrote:
But I'm having problems with one of the functions:
func3 f l = l ++ map f l
While we're at it: The best thing I could come up for
func2 f g l = filter f (map g l)
is
func2p f g = (filter f) . (map g)
Which isn't exactly point-_free_. Is it possible to reduce that furth
Hi Julien,
func3 f l = l ++ map f l
func3 f = ap (++) (map f)
func3 = ap (++) . map
Looks pretty clear and simple. However, I can't come up with a solution.
Is it even possible to remove one of the variables, f or l? If so, how?
I have no idea how to do this - the solution is to log into #ha
Hi
func2 f g l = filter f (map g l)
is
func2p f g = (filter f) . (map g)
func2 = (. map) . (.) . filter
Again, how anyone can come up with a solution like this, is entirely
beyond me...
Thanks
Neil
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On Friday 01 September 2006 11:44, Neil Mitchell wrote:
> Hi
>
> > func2 f g l = filter f (map g l)
> > is
> > func2p f g = (filter f) . (map g)
>
> func2 = (. map) . (.) . filter
>
> Again, how anyone can come up with a solution like this, is entirely
> beyond me...
To answer part of the OP's que
I read the easy parts of the "Associated Types with Class" and "Associated Type Synonyms" papers. An associated type synonym seems to kind of work similarly to a restricted form of class. In what way are the two following examples different?
-- define a class with a type synonym, and a set of o
Hello Tamas,
Friday, September 1, 2006, 1:52:03 PM, you wrote:
>> >> | type Point = (State, State, Int)
>> > | type TypeV = Array Point Double
>>
>> which will require 128 gigs of memory for 32-bit cpus and even
>> slightly more for 64-bit ones :)
> Bulat,
> Can you please explain this? The f
From: Julien Oster <[EMAIL PROTECTED]>
Subject: [Haskell-cafe] Exercise in point free-style
I was just doing Exercise 7.1 of Hal Daumé's very good "Yet Another
Haskell Tutorial". It consists of 5 short functions which are to be
converted into point-free style (if possible).
It's insightful and a
Brian,
I read the easy parts of the "Associated Types with Class" and
"Associated Type Synonyms" papers. An associated type synonym seems
to kind of work similarly to a restricted form of class. In what
way are the two following examples different?
-- define a class with a type synony
Julien Oster wrote:
> While we're at it: The best thing I could come up for
>
> func2 f g l = filter f (map g l)
>
> is
>
> func2p f g = (filter f) . (map g)
>
> Which isn't exactly point-_free_. Is it possible to reduce that further?
Sure it is:
func2 f g l = filter f (map g l)
func2 f g = (
Hello Brian,
Friday, September 1, 2006, 8:32:55 PM, you wrote:
> I read the easy parts of the "Associated Types with Class" and
> "Associated Type Synonyms" papers. An associated type synonym seems
> to kind of work similarly to a restricted form of class. In what way
> are the two following exam
Hi,
I am newbie, reading the Gentle Introduction. Chapter 7
(Input/Output) says
Pragmatically, it may seem that getContents must immediately read an
entire file or channel, resulting in poor space and time performance
under certain conditions. However, this is not the case. The key
point
On Friday 01 September 2006 15:19, Tamas K Papp wrote:
> Hi,
>
> I am newbie, reading the Gentle Introduction. Chapter 7
> (Input/Output) says
>
> Pragmatically, it may seem that getContents must immediately read an
> entire file or channel, resulting in poor space and time performance
> und
On Fri, 2006-09-01 at 16:28 -0400, Robert Dockins wrote:
> On Friday 01 September 2006 15:19, Tamas K Papp wrote:
> > Hi,
> >
> > I am newbie, reading the Gentle Introduction. Chapter 7
> > (Input/Output) says
> >
> > Pragmatically, it may seem that getContents must immediately read an
> > ent
On Friday 01 September 2006 16:46, Duncan Coutts wrote:
> On Fri, 2006-09-01 at 16:28 -0400, Robert Dockins wrote:
> > On Friday 01 September 2006 15:19, Tamas K Papp wrote:
> > > Hi,
> > >
> > > I am newbie, reading the Gentle Introduction. Chapter 7
> > > (Input/Output) says
> > >
> > > Pragma
On Fri, 1 Sep 2006, Robert Dockins wrote:
> On Friday 01 September 2006 16:46, Duncan Coutts wrote:
...
>> Note also, that with lazy IO we can write really short programs that are
>> blindingly quick. Lazy IO allows us to save a copy through the Handle
>> buffer.
(Never understood why some people
On Friday 01 September 2006 18:01, Donn Cave wrote:
> On Fri, 1 Sep 2006, Robert Dockins wrote:
> > On Friday 01 September 2006 16:46, Duncan Coutts wrote:
>
> ...
>
> >> Note also, that with lazy IO we can write really short programs that are
> >> blindingly quick. Lazy IO allows us to save a copy
On Fri, 2006-09-01 at 17:36 -0400, Robert Dockins wrote:
> Perhaps I should be more clear. When I said "advanced" above I meant "any
> use
> whereby you treat a file as random access, read/write storage, or do any kind
> of directory manipulation (including deleting and or renaming files)". L
Duncan Coutts wrote:
Hi,
> In practise I expect that most programs that deal with file IO strictly
> do not handle the file disappearing under them very well either. At best
> the probably throw an exception and let something else clean up.
And at least in Unix world, they just don't disappear.
Udo Stenzel wrote:
Thank you all a lot for helping me, it's amazing how quickly I received
these detailed answers!
> func2 f g l = filter f (map g l)
> func2 f g = (filter f) . (map g) -- definition of (.)
> func2 f g = ((.) (filter f)) (map g) -- desugaring
> func2 f = ((.) (filter f)) . m
An easy way to solve this is to ask lambdabot. Log on to the Haskell
IRC channel:
lennart: @pl \ f l -> l ++ map f l
lambdabot: ap (++) . map
Notice how it's much shorter than the Hughes' solution. :)
-- Lennart
On Sep 1, 2006, at 13:11 , John Hughes wrote:
From: Julien Oster <[EM
Shorter, although perhaps less insightful.
Bob
On 2 Sep 2006, at 01:36, Lennart Augustsson wrote:
An easy way to solve this is to ask lambdabot. Log on to the
Haskell IRC channel:
lennart: @pl \ f l -> l ++ map f l
lambdabot: ap (++) . map
Notice how it's much shorter than the Hughes' sol
Julien Oster wrote:
> = ((.) (filter f)) . map g l
> = (.)((.) . filter f)(map) g l -- desugaring
> = (.map)((.) . filter f) g l -- sweeten up
> = (.map) . (.) . filter g l-- definition of (.)
By the way, I think from now on, when doing point-free-ify
haskell:
> Hello,
>
> I was just doing Exercise 7.1 of Hal Daum?'s very good "Yet Another
> Haskell Tutorial". It consists of 5 short functions which are to be
> converted into point-free style (if possible).
>
> It's insightful and after some thinking I've been able to come up with
> solution
haskell:
> Julien Oster wrote:
>
> >But I'm having problems with one of the functions:
> >
> >func3 f l = l ++ map f l
>
> While we're at it: The best thing I could come up for
>
> func2 f g l = filter f (map g l)
>
> is
>
> func2p f g = (filter f) . (map g)
>
> Which isn't exactly point-_fre
Quoth Julien Oster <[EMAIL PROTECTED]>:
...
| But what happens when two processes use the same file and one process is
| writing into it using lazy IO which didn't happen yet? The other process
| wouldn't see its changes yet.
That's actually a much more general problem, one that I imagine applies
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