On Tue, 2007-07-31 at 22:45 -0700, Alex Jacobson wrote:
If you create a Data.Map or Data.Set larger than fits in physical
memory, will OS level swapping enable your app to behave reasonably or
will things just die catastrophically as you hit a memory limit?
It will die (catastrophically or
Bulat Ziganshin wrote:
apfelmus wrote:
avoid the small layer of imperative code, of course. But the more you
treat imperative code as somewhat pure, the greater the danger that the
purely functional logic will be buried inside a mess of imperative code.
In other words, the goal is exactly to
Hello all,
Maybe this is a wrong place to report, but I have repeatedly performed
funny calculation in GHCi with strange time report. The version of
GHCi is:
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6, for Haskell 98.
/ /_\\/ __ / /___|
Thank you all for your references and tips, I'll be using them. :-)
On 06/08/2007, Jules Bean [EMAIL PROTECTED] wrote:
Thomas Schilling wrote:
On 6 aug 2007, at 22.11, Paulo J. Matos wrote:
If you're used to Slime+Paredit, then there isn't something really
comparable, but you get some
Hello apfelmus,
Wednesday, August 8, 2007, 11:33:41 AM, you wrote:
it's point of view of theoretical purist. i consider Haskell as
language for real world apps and need to write imperative code appears
independently of our wishes. in paricular, it's required to write very
efficient code, to
Isaac Dupree wrote:
In class Integral, divMod has a default in terms of quotRem.
(quot,rem,div,mod all have defaults as the both-function they're part
of.) I'm sure divMod is more natural than quotRem to implement for some
types... so why doesn't quotRem have a default in terms of divMod? it
Claus Reinke wrote:
there is usually a way to interpret monadic structures built in
this way (a 'run' operation of some kind).
The run operation of type (m a - a) is the (comonadic) coreturn. Many
monads are almost comonads too, for a meaning of almost to be made
precise.
Claus Reinke
G'day all.
Quoting Vimal [EMAIL PROTECTED]:
Well, Dancing Links (DLX) is just a data structure + few techniques
to help with the backtrack, after modeling Sudoku as a contraint
satisfaction problem.
DLX is one realisation of an algorithm which works on boolean matrices.
It's a pointer-based
Hi, I am learning the haskell programming language and had tried to define the
following types:
type Scenario = (String, String, [Step])
type Step = (String, Scenario, String, String, String)
Notice that Scenario depends on a list of steps and Step has a dependence with
scenario. I know that
rodrigo.bonifacio [EMAIL PROTECTED] writes:
Hi, I am learning the haskell programming language and had
tried to define the following types:
type Scenario = (String, String, [Step]) type Step =
(String, Scenario, String, String, String)
data Scenario = Scenario String String [Step]
data
apfelmus wrote:
However, most genuinely imperative things are often just a building
block for a higher level functional model. The ByteString library is a
good example: the interface is purely functional, the internals are
explicit memory control. It's a bad idea to let the internal memory
Seth Gordon wrote:
Functors are a generalization from lists to things that can be mapped
over in general, and then monads are a generalization of functors.
Way to go! That way lies true co/monadic enlightenment. Put another way,
monads are no more about (only) IO/sequencing than fmap is
I’m having difficulty to understand what phantom types are good for. Is this
just for improving runtime performance?
I read the wiki, and it says this is useful if you want to increase the
type-safety of your code, but the code below does not give a compiler error
for the function test1, I get a
Rodrigo wrote:
type Scenario = (String, String, [Step])
type Step = (String, Scenario, String, String, String)
Recursive types are not supported by type-declarations. use data
declarations instead:
data Scenario = Scenario String String [Step]
data Step = Step String Scenario String
Notice that Scenario depends on a list of steps and Step has a dependence
with scenario. I know that this is a kind of bad smell in Haskell, are
there any pattern or language idiom to deal with cyclical dependences?
Just a little something to add, this is not a bad smell at all... in
Brian Hulley wrote:
hidden away in the definition of their API function to create a label,
is a call to (ref 0) ;-) The equivalent implementation in Haskell
would completely destroy all hope of using this in a pure context and
force all use of the API into the IO monad.
Really? I would
peterv wrote:
I’m having difficulty to understand what phantom types are good for.
I read the wiki, and it says this is useful if you want to increase the
type-safety of your code, but the code below does not give a compiler error
for the function test1, I get a runtime error, just like test2.
Im having difficulty to understand what phantom types are good for. Is
this just for improving runtime performance?
No. As the wiki says, you can use them to add static guarantees.
I read the wiki, and it says this is useful if you want to increase the
type-safety of your code, but the
On Aug 8, 2007, at 11:16 AM, peterv wrote:
I’m having difficulty to understand what phantom types are good
for. Is this
just for improving runtime performance?
I found phantom types to be useful in the implementation of bit-wise
set operations. You can find the code Edison:
C-c C-b ... when pressed for the first time this will start an
interpreter (ghci or hugs most of the time), when pressed with a
running interpreter it'll switch to that buffer.
C-c C-l ... Load the current file into the editor. There is no
function-wise compilation.
More generally, in
I've removed it from the next release of haskell-mode, so if you need it,
please explain why.
So C-c C-l is the preferred method for re-loading? I don't know enough
about the details to know if :l and :r do exactly the same things in
ghci.
___
On 8/8/07, Brian Hulley [EMAIL PROTECTED] wrote:
In contrast, all the pure functional GUIs that I've seen are just
wrappers around someone else's imperative code, and moreover, they
exchange the simplicity of the object oriented imperative API for a
veritable mindstorm of unbelievably heavy,
I've removed it from the next release of haskell-mode, so if you need it,
please explain why.
So C-c C-l is the preferred method for re-loading?
Yes.
I don't know enough about the details to know if :l and :r do exactly the
same things in ghci.
I don't either. But experimentation
On 8/8/07, Brian Hulley [EMAIL PROTECTED] wrote:
Regarding the quote above, if the API must hide explicit memory control
from the user the only way I can see of doing this would be to use
(unsafePerformIO), which really is unsafe since Haskell relies on the
fact that mutable operations can't
Martin Percossi wrote:
Brian Hulley wrote:
hidden away in the definition of their API function to create a
label, is a call to (ref 0) ;-) The equivalent implementation in
Haskell would completely destroy all hope of using this in a pure
context and force all use of the API into the IO
Kim-Ee Yeoh wrote:
Seth Gordon wrote:
Functors are a generalization from lists to things that can be mapped
over in general, and then monads are a generalization of functors.
Way to go! That way lies true co/monadic enlightenment.
I feel like I still don't understand comonads. Maybe I
On Wed, Aug 08, 2007 at 12:57:51PM -0400, Stefan Monnier wrote:
I've removed it from the next release of haskell-mode, so if you need it,
please explain why.
So C-c C-l is the preferred method for re-loading?
Yes.
I don't know enough about the details to know if :l and :r do exactly
Hugh Perkins wrote:
On 8/8/07, *Brian Hulley* [EMAIL PROTECTED]
mailto:[EMAIL PROTECTED] wrote:
In contrast, all the pure functional GUIs that I've seen...
In defense of Haskell (wow!), note that imperative languages are not
without problems in GUIs. In a multithreaded environment,
If
Hello,
I have created the following function:
dist :: String - [[String]] - [[String]]
dist x y = [ x:e | e-y ]
eg.:
dist 1M [[], [2M], [2M, 3M]] = [[1M],[1M,2M],[1M,2M, 3M]]
How can I create an operator that perform the same function as dist? I want to
write something like:
1M ++ [[],
Thanks, that is a much clearer explanation than
http://en.wikibooks.org/wiki/Haskell/Phantom_types
Peter
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Arie Peterson
Sent: Wednesday, August 08, 2007 5:59 PM
To: haskell-cafe@haskell.org
Subject: Re:
On Wed, 8 Aug 2007, peterv wrote:
PS: It would be very nice for beginners to have a special tool / text editor
that allows you see the desugared form of monads and other constructs.
An editor that can be configured to display various inferred details,
annotations and desugarings in the
On Wed, 8 Aug 2007, Paul Hudak wrote:
...
Well, you could argue, monad syntax is what really made Haskell become
more accepted by the masses, and you may be right (although perhaps
Simon's extraordinary performance at OSCOM is more of what we need). On
the other hand, if we give imperative
On 8/9/07, peterv [EMAIL PROTECTED] wrote:
IMHO and being a newbie having 20 years of professional C/C++/C#
experience but hardly any Haskell experience, I agree with this… I find the
monad syntax very confusing, because it looks so much like imperative code,
but it isn't. Personally I also
Hello,
:r is also *much* faster in general; :l reloads all modules from
scratch, while :r only reloads the modules that have changed.
:r also doesn't seem check the import declarations for changes. For
example, if I add a new import statement to my file, without adding code
which uses the
As a newbie (okay I will not write this again, you all know I'm a newbie by now
;-), I don't understood what the problem of a pure functional GUI is.
To me, having an imperative background, a graphical application is just a big
tree of data that evolves when events from the OS come in. (this
On Wed, 2007-08-08 at 19:14 +, Peter Verswyvelen wrote:
So could you please tell me more about the problem with pure
functional GUIs and why this is not part of the Haskell library? I
mean a GUI library completely written in Haskell, not wrapping a
popular library.
Partly because just
Well, if you want to make it as big as QT, yes.
But even just a simple purely functionaly GUI framework that is part of the
library would be nice, because right now it gives the impression it cannot be
done in Haskell... E.g. Concurrent Clean seems to have a simple UI library.
-
On Wed, Aug 08, 2007 at 02:20:39PM -0400, Paul Hudak wrote:
All of the recent talk of support for imperative programming in Haskell
makes me really nervous. To be honest, I've always been a bit
uncomfortable even with monad syntax. Instead of:
do x - cmd1
y - cmd2
...
On Aug 8, 2007, at 3:14 PM, Peter Verswyvelen wrote:
So could you please tell me more about the problem with pure
functional GUIs and why this is not part of the Haskell library? I
mean a GUI library completely written in Haskell, not wrapping a
popular library.
I had quite a lot of
Using The Darcs version of HList (http://darcs.haskell.org/HList/), I
can do simple things with (H)lists just fine, so
--angus = Key 42
-- .*. Name Angus
-- .*. Cow
-- .*. Price 75.5
-- .*. HNil
--main = putStrLn (show angus)
works, On the other hand examples from the HList
Paul Hudak wrote:
All of the recent talk of support for imperative programming in
Haskell makes me really nervous
... if we give imperative programmers the tools to do all the things
they are used to doing in C++, then we will be depriving them of the
joys of programming in the
On Wed, Aug 08, 2007 at 08:22:41PM +, Peter Verswyvelen wrote:
Well, if you want to make it as big as QT, yes.
But even just a simple purely functionaly GUI framework that is part of the
library would be nice, because right now it gives the impression it cannot be
done in Haskell...
To be fair, GTK is pretty standard. This is so even for big name gc'd
imperative languages such as C#. Sure, you can use Windows.Forms in C#, but
you often wouldnt, because of the patent burden. Also, gtk in partnership
with glade rocks!
How easy is gtk to use from haskell by the way? In gc'd
I can't agree with your point about Haskell being (just) a prototype language (assuming that's what
you meant). If that's the case, it won't last very long. Languages need to be something you can
write real, practical applications in. Fortunately, Haskell isn't just a prototype language. I'm
brianh:
Hugh Perkins wrote:
On 8/8/07, *Brian Hulley* [EMAIL PROTECTED]
mailto:[EMAIL PROTECTED] wrote:
In contrast, all the pure functional GUIs that I've seen...
In defense of Haskell (wow!), note that imperative languages are not
without problems in GUIs. In a multithreaded
Other question on using gtk from haskell: how easy is it to integrate
with glade? ie, can we directly bind glade form elements to haskell
variables? How easy is it to bind events to glade form elements from
within Haskell?
Download the source and have a look at the demo/glade
On 9 Aug 2007, at 8:41 am, David Roundy wrote:
I may be stating the obvious here, but I strongly prefer the do
syntax.
It's nice to know the other also, but the combination of do
+indenting makes
complicated code much clearer than the nested parentheses that
would be
required with purely =
On 8/9/07, Marc Weber [EMAIL PROTECTED] wrote:
-- load up the glade file
dialogXmlM - xmlNew simple.glade
let dialogXml = case dialogXmlM of
(Just dialogXml) - dialogXml
Nothing - error can't find the glade file \simple.glade\
\
On 8/9/07, ok [EMAIL PROTECTED] wrote:
We get extra , =, \, -, and in tokens, but no new parentheses.
Yes exactly. It's the = and that gets rid of the parentheses, and
reverses the order of the operations.
I cant remember where I saw this, but somewhere there is a monad tutorial
that starts
Hello Peter,
Wednesday, August 8, 2007, 11:14:37 PM, you wrote:
To me, having an imperative background, a graphical application is
just a big tree of data that evolves when events from the OS come
in. (this data is NOT per se the data for the GUI element; instead
use the
Hello Paul,
Wednesday, August 8, 2007, 10:20:39 PM, you wrote:
we need). On the other hand, if we give imperative programmers the
tools to do all the things they are used to doing in C++, then we
will be depriving them of the joys of programming in the Functional
Way. How many times have
Hello Hugh,
Thursday, August 9, 2007, 4:59:04 AM, you wrote:
How easy is gtk to use from haskell by the way? In gc'd
imperative languages, typically only one thread is allowed to
communicate with the GUI, and you need to set up a whole bunch of
message-parsing stuff to communicate with
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