On 8/13/07, David Roundy [EMAIL PROTECTED] wrote:
Try executing:
do { x - return 2; undefined; return (x*x); }
in any monad you like
instance Monad M where
return a = M a
~(M a) = f = f a
Or is that cheating?
--
Dan
___
Haskell-Cafe
On 8/13/07, Benjamin Franksen [EMAIL PROTECTED] wrote:
Ok, I admit defeat now ;-) Monads in general /allow/ sequencing of (certain)
effects, but it is not necessary for a monad to do so.
I'm sure I said that 300 or so posts ago :-)
Here's an example that might help make some of this explicit.
On 8/14/07, Jeff Polakow [EMAIL PROTECTED] wrote:
One general intuition about monads is that they represent computations
rather than simple (already computed) values:
x :: Int -- x is an Int
x :: Monad m = m Int -- x is a computation of an Int
What's a computation? It
On 8/14/07, Sebastian Sylvan [EMAIL PROTECTED] wrote:
I like the very light weight analogy (which works for most practical
uses of monads) that a monadic action is a recipe
Many introductory programming books present the idea of a program as a
recipe. Here's a recipe for computing factorials:
On 8/14/07, Lennart Augustsson [EMAIL PROTECTED] wrote:
You don't normally call x::Int a computation of an Int because there's
nothing that distinguishes the value of the x from what it was before you
computed it.
Can you spell out exactly what you mean by this?
So I prefer to regard x as a
On 8/14/07, Sebastian Sylvan [EMAIL PROTECTED] wrote:
On 14/08/07, Dan Piponi [EMAIL PROTECTED] wrote:
Where do monads come in?
Well I would try to distinguish between code that we write to compute
values, and values which represent monadic actions when coming up with
analogies.
How would
On 8/14/07, Sebastian Sylvan [EMAIL PROTECTED] wrote:
Well that's easy, don't use the recipe analogy to explain code, use it
for monadic values exclusively, and you avoid the confusion entirely!
I don't think it's that complicated.
It certainly is complicated. I think I have a good grasp of
On 8/14/07, Dan Weston [EMAIL PROTECTED] wrote:
Conor McBride and Ross Paterson said it best in the introduction to
their paper Applicative programming with effects [1]:
As von Neumann said: Young man, in mathematics you don't understand
things, you just get used to them.
Getting used to
On 8/15/07, Andy Gimblett [EMAIL PROTECTED] wrote:
I assumed he was just trying not to sing the Spider Pig song.
I've been banned from singing that around the house. And the cat version.
But I was mainly thinking about how the physicist's definition of
tensor needn't be accepted as an
On 8/14/07, Dougal Stanton [EMAIL PROTECTED] wrote:
I'm looking for cool but mind-bending examples of functional brilliance.
One of my favourite examples is:
http://citeseer.ist.psu.edu/hinze99functional.html
Anyone who studies binomial heaps is struck by the similarity to
binary arithmetic.
On 8/15/07, Dan Weston [EMAIL PROTECTED] wrote:
You too could have invented Universal Algebra and Category Theory.
I nominate Dan Piponi to write it and eagerly await its release!
I've already started on it. Well, that's not the exact title and
subject. And as an example I'll probably use
On 8/17/07, Andrew Coppin [EMAIL PROTECTED] wrote:
I've seen comments in various places that monads allow you to borrow
things from the future.
That sounds completely absurd to me... can anybody explain?
Suppose you buy into the notion that monads sequence actions. Then
consider the following
On 8/17/07, Dan Piponi [EMAIL PROTECTED] wrote:
On 8/17/07, Andrew Coppin [EMAIL PROTECTED] wrote:
That sounds completely absurd to me... can anybody explain?
Except...you can switch on ghc's special time travel features...
On reflection I decided my example isn't very convincing. For one
On 8/18/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Surely all this means is that the magical mdo keyword makes the
compiler arbitrarily reorder the expression...?
What mdo actually does is described here:
http://www.cse.ogi.edu/PacSoft/projects/rmb/mdo.pdf
My last example desugars to:
test =
This isn't really a Haskell question but I'm guessing some Haskell
hackers have a solution. MacOS X's Spotlight doesn't seem to be able
to search for text in .lhs and .hs files. But it can find text in .txt
files. Is there a way of getting Spotlight to treat .lhs and .hs files
like .txt files so I
On 8/20/07, David Ritchie MacIver [EMAIL PROTECTED] wrote:
I was playing with some code for compiling regular expressions to finite
state machines and I ran into the following problem.
I've met exactly the same problem myself and you got me interested in it again.
I think the tricky part isn't
On 8/27/07, Peter Verswyvelen [EMAIL PROTECTED] wrote:
Look at Template Haskell.
Gee coming from C++ that was the last thing I expected templates to do. It
seems a bit more powerful in Haskell though!
There's much in common between C++ template metaprogramming and
template Haskell - they
On 8/29/07, Hugh Perkins [EMAIL PROTECTED] wrote:
Well, a quick google for are graphics cards turing complete?
suggests that some nVidia cards are Turing complete
http://developer.nvidia.com/object/cuda.html
It's a C compiler with multiprocessor streaming extensions that
targets nvidia cards.
On 8/30/07, Peter Hercek [EMAIL PROTECTED] wrote:
f x =
let x = x * scale in
let x = x + transform in
g x
Why are you trying to call three different things by the same name 'x'
in one tiny block of code? That's very confusing and makes it hard to
reason equationally about the code.
On 8/30/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Obviously you might very well have *meant* to write x = f x. But would
it be possible to add some kind of optional compiler warning to find
such assignments?
The thing that convinced me to learn Haskell in the first place was
the fact that you
On 8/30/07, Andrew Coppin [EMAIL PROTECTED] wrote:
Yeah, but... programs aren't like mathematics. I know people claim that
they are, but they aren't.
But the raison d'etre of Haskell is to make programming more like
mathematics. That motivates everything from the fact that it's a
declarative
On 8/30/07, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
Dan Piponi writes:
In Haskell, there is no box.
Well, there are boxes...
But there also thunks and latent, yet-unevaluated graphs...
But the point of Haskell is to provide an abstraction that hides these
details from you. (Though
On 9/3/07, Vimal [EMAIL PROTECTED] wrote:
Hi
In my Paradigms of Programming course, my professor presents this piece of
code:
while E do
S
if F then
break
end
T
end
This is seriously offtopic but kinda fun anyway...
There's a nice formalism for investigating this kind of
On 9/5/07, Ketil Malde [EMAIL PROTECTED] wrote:
On Wed, 2007-09-05 at 08:19 +0100, Simon Peyton-Jones wrote:
Error message from GHCi:
test/error.hs:2:8:
No instance for (Num String)
arising from use of `+' at test/error.hs:2:8-17
Possible fix: add an instance
On 9/6/07, Dougal Stanton [EMAIL PROTECTED] wrote:
On 06/09/07, Sebastian Sylvan [EMAIL PROTECTED] wrote:
[2,3,4,9,16,29,54,99,182,335] -- what's this?
Two times this: http://www.research.att.com/~njas/sequences/A000213
plus this: http://www.research.att.com/~njas/sequences/A001590
plus two
On 9/5/07, Max Vasin [EMAIL PROTECTED] wrote:
2007/9/5, Peter Verswyvelen [EMAIL PROTECTED]:
Looks really nice, but if I understand it correctly it is specific for
X, so does not work on Windows?
This kind of programs is impossible in Windows. Of cause you can use X
server for Windows and
On 9/11/07, Andrew Coppin [EMAIL PROTECTED] wrote:
you can fall down a monad and not be able to
escape...
It's not so bad. It's in the nature of monads that after you've fallen
in once, you can never get trapped any deeper.
--
Dan
___
Haskell-Cafe
On 9/12/07, PR Stanley [EMAIL PROTECTED] wrote:
The same should apply to head and tail. head or tail of [] should be
Disagree, strongly. Its not even possible for head,
What's the logic behind this?
You don't need anything sophisticated for this. What possible total
function could have
On 9/16/07, apfelmus [EMAIL PROTECTED] wrote:
But unfortunately, finiteness is a special property that the type system
cannot guarantee. The above type signature for cons doesn't work since
the following would type check
bad :: a - List Nonempty Finite a
bad x = let xs = cons x xs in
On 9/25/07, Brian Hulley [EMAIL PROTECTED] wrote:
...I seem to dimly recall that there is a natural language
somewhere that also uses it but I can't remember which one.
Every permutation of [S,V,O] appears in 'nature':
http://en.wikipedia.org/wiki/Word_order.
Also, a problem might be that it
On 9/26/07, Lennart Augustsson [EMAIL PROTECTED] wrote:
Things can go arbitrarily wrong if you misuse unsafePerformIO, you can even
subvert the type system.
So...if I was in a subversive kind of mood (speaking hypothetically),
what would I have to do?
--
Dan
On 9/26/07, Jorge Marques
On 10/6/07, Andrew Coppin [EMAIL PROTECTED] wrote:
I've seen quite a few people do crazy things to abuse the Haskell type
system in order to perform arithmetic in types.
How did you know precisely what I was doing at this moment in time?
Stuff the type system
was never ever intended to do.
On 10/9/07, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
So, you assume that acos should have a *default* implementation in the
Floating class? Propose it, please.
I don't think the proposal makes any such assumption. It implies only
that *if* you provide acos, pi will be provided for you
On 10/9/07, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
Yes, sorry, I slipped... I was so against the acos(-1) /or atan(...)/
solution, that I wrote anything...
+1, Honest
--
Dan
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Jules Bean said:
If it is true of many Floating instances that (atan 1 * 4) is an
accurate way to calculate pi (and it appears to be 'accurate enough' for
Float and Double, on my computer) then adding it as a default doesn't
appear to do any harm.
Maybe this is the wrong point of view, but I
Steve said:
How, then, is that any different from a general-purpose programming
language? You're just drawing the line in the sand in a different
place.
In a way it is like drawing a line in sand. But that's a useful thing
to do for a bunch of reasons.
(1) When developing code, you'd like to
On 10/12/07, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
He wants to write entire programs in the type system,
something like the crazies who write programs in C++ templates such
that template expansion does all the work at compile time
Crazies? :-)
Andrew said:
Oh, and the irony of using OpenGL (an API of unimaginable complexity) just to
write pixels to the screen. Isn't that kind of like using a thermonuclear
device to crack a nut?
Saying that using OpenGL to write pixels to the screen is like using a
thermonuclear device to crack a
On 10/14/07, Yitzchak Gale [EMAIL PROTECTED] wrote:
Not very much, I suspect. That monad really is broken -
it's not a monad at all.
Depending on your point of view, ListT isn't broken. It correctly
transforms commutative monads into monads. The problem is that you
can't express commutative
On 10/14/07, Yitzchak Gale [EMAIL PROTECTED] wrote:
Interesting. What do you mean by a commutative monad?
It can't be a monad with some sort of additional commutative
law, because the old ListT doesn't even satisfy the monad
laws. Or does it in some sense?
If m is a commutative monad, then
I was just putting together my Amazon wish list and was wondering if
there are any great books on Haskell and/or functional programming
that people think are must-reads. Okasaki's Purely Functional
Programming, Pierce's Types and Programming Languages are frequent
recommendations. Smullyan's To
The mathematics is probably the most reliable part of Wikipedia.
--
Dan
On 10/17/07, PR Stanley [EMAIL PROTECTED] wrote:
Hi
Do you trust mathematical materials on Wikipedia?
Paul
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the potential for a
nice and efficient image processing library that inherits its laziness
directly from Haskell.
On 10/30/07, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
Dan Piponi adds to a short exchange:
jerzy.karczmarczuk:
[iso-8859-1] Bj�rn Wikstr�m writes:
Hi! I have lots and lots
On 10/31/07, Neil Mitchell [EMAIL PROTECTED] wrote:
in the long run Haskell should be aiming for equivalence with highly
optimised C.
Really, that's not very ambitious. Haskell should be setting its
sights higher. :-)
When I first started reading about Haskell I misunderstood what
currying was
On 11/2/07, Greg Fitzgerald [EMAIL PROTECTED] wrote:
Anybody know of an ARM back end for any of the Haskell compilers?
This version of hugs worked on my (ARM based) NSLU2:
http://ipkgfind.nslu2-linux.org/details.php?package=hugsofficial=format=
-
Dan
There are some nice formulae for the Fibonacci numbers that relate f_m
to values f_n where n is around m/2. This leads to a tolerably fast
recursive algorithm.
Here's a complete implementation:
fib 0 = 0
fib 1 = 1
fib 2 = 1
fib m | even m = let n = m `div` 2 in fib n*(fib (n-1)+fib (n+1))
I see lots of shootout examples where Haskell programs seem to perform
comparably with C programs, but I find it hard to reproduce anything
like those figures when testing with my own code. So here's a simple
case:
I have this C program:
#include stdio.h
#define n 1
double a[n];
int
On Nov 8, 2007 2:48 PM, Duncan Coutts [EMAIL PROTECTED] wrote:
You really do not need happy to build ghc. Just ignore the extralibs
tarball.
Well that was the crucial fact I needed. 6.8.1 is now built. ghci
doesn't work, it complains about an unknown symbol '_environ' in
HSbase-3.0.0.0.o but I
On Nov 8, 2007 11:34 AM, Jason Dusek [EMAIL PROTECTED] wrote:
Can you show us your compilation options and timings?
I was simply using -O3. I tried a bunch of other flags (copied from
the shootout examples) but they made no appreciable difference.
I was getting about 1.5s for the Haskell
Bulat,
The strictness gave me something like a 10% performance increase
making the Haskell code more than 10 times slower than the C. Is this
the right type of array to use for performance?
--
Dan
On Nov 8, 2007 10:36 AM, Bulat Ziganshin [EMAIL PROTECTED] wrote:
Hello Dan,
Thursday, November
Mikhail,
main = do
print $ foldl' (+) 0 $ take 1 [1.0,1.0..]
works 10 times faster than your C version. You just need to adapt to the
radically different style of programming.
My wasn't intended to represent the problem that I'm trying to solve,
but the approach I want to take.
On Nov 8, 2007 11:24 AM, Thomas Schilling [EMAIL PROTECTED] wrote:
Wow. You should *really* try using GHC 6.8.1:
I was hoping you weren't going to say that :-) As soon as I find a
suitable 64-bit Intel binary for MacOSX, or can bootstrap my way out
of happy needing happy in my attempted source
On Nov 8, 2007 11:36 AM, Paul Brown [EMAIL PROTECTED] wrote:
All that said, I'm not sure where I got the GHC that I used to build
the 6.6.1 via MacPorts; I think it shipped with MacOS once upon a time.
sudo port install ghc
. . .
configure: error: GHC is required unless bootstrapping from .hc
On Nov 8, 2007 12:16 PM, Don Stewart [EMAIL PROTECTED] wrote:
If you can post the code somewhere, that would be great, with examples
of how to reproduce your timings.
The code is exactly what I posted originally (but nore that n is 10
times larger in the C code). I compiled using ghc -O3 -o
On Nov 8, 2007 12:36 PM, Don Stewart [EMAIL PROTECTED] wrote:
dpiponi:
Can you start by retrying with flags from the spectral-norm benchmark:
http://shootout.alioth.debian.org/gp4/benchmark.php?test=spectralnormlang=ghcid=0
Actually, that was my starting point for investigating how to
On Nov 8, 2007 10:28 PM, Bulat Ziganshin [EMAIL PROTECTED] wrote:
just for curiosity, can you try to manually unroll loop and see
results?
I don't get any noticeable performance change when I unroll the loop
by 2 by hand. I suspect that on a modern CPU loop unrolling probably
isn't that much
On Nov 9, 2007 11:30 AM, Brent Yorgey [EMAIL PROTECTED] wrote:
More generally, this is due to the fact that floating-point numbers can only
have finite precision
This popped up on reddit recently:
http://blogs.sun.com/jag/entry/transcendental_meditation .
Interestingly, AMD did apparently
This isn't a question specific to ghc. In general, the process of
bootstrapping compilers and porting them to new platforms can be
described by T-diagrams. When I did a web search on T-diagrams the
first hit I found,
... linking ... done.
Ok, modules loaded: Main.
Prelude Main main
1
Prelude Main x
interactive:1:0: Not in scope: `x'
Prelude Main Leaving GHCi.
---
On Jul 23, 2007 10:46 AM, Dan Piponi [EMAIL PROTECTED] wrote:
Ian said:
Can you please give
On Nov 12, 2007 1:59 PM, Henning Thielemann
[EMAIL PROTECTED] wrote:
See
http://www.haskell.org/ghc/docs/latest/html/users_guide/interactive-evaluation.html
I guess the key sentence is:
For technical reasons, GHCi can only support the *-form for modules
which are interpreted, so compiled
On Nov 13, 2007 3:00 AM, Simon Peyton-Jones [EMAIL PROTECTED] wrote:
Dan, can you suggest any words we could add to the
documentation that would have prevented you stumbling?
I guess the thing that would have helped best would have been an error
message like 'x' not in scope,
On Nov 13, 2007 1:24 PM, Ryan Ingram [EMAIL PROTECTED] wrote:
I tend to prefer where, but I think that guards function declarations are
more readable than giant if-thens and case constructs.
Up until yesterday I had presumed that guards only applied to
functions. But I was poking about in the
On Nov 28, 2007 9:20 PM, Chris Smith [EMAIL PROTECTED] wrote:
I intend to naively treat each function as being from the reals to the
reals, and then take advantage of the fact (which is proven by the type
system in the code I posted) that when the derivative is evaluated at
integer inputs for
Chris,
So I want the parameter to be more restricted. No one is going to write
a function that *only* works on AD types.
But exporting AD doesn't force people to write functions that work on
AD types, people can write whatever functions they like. They're only
constrained if they want to pass
Chris,
I could change my implementation; I could use Jerzy's
implementation...launch Mathematica...
But all of these could be implemented by introducing a different type
constructor called AD for each one. You could switch the
implementation of AD on the user and they wouldn't have to change a
On Dec 3, 2007 1:09 PM, Denis Bueno [EMAIL PROTECTED] wrote:
I don't think I can conclude that there are *no* reasons to teach the
do-notation first. I just think that it is more instructive to teach
it later.
It's standard in mathematics teaching, when introducing a mathematical
structure
On Dec 3, 2007 3:54 PM, Ben Franksen [EMAIL PROTECTED] wrote:
I don't buy this. As has been noted by others before, IO is a very special
case, in that it can't be defined in Haskell itself, and there is no
evaluation function runIO :: IO a - a.
I'm not sure what a function of type m a - a has
Is there anything in any of the interfaces to Integer that will allow
me to quickly find the highest bit set in an Integer? If not, does
anyone have any recommendations for how to do it efficiently. There
are some obvious things that come to mind but which might involve
quite a bit of useless
On Dec 3, 2007 6:36 PM, Ben Franksen [EMAIL PROTECTED] wrote:
then the special features of IO
will remain associated with monads in general, leading to a whole jumble of
completely wrong ideas about them.
As I only learnt about monads a couple of years ago, the process is
still fresh in my
On Dec 3, 2007 9:10 PM, Don Stewart [EMAIL PROTECTED] wrote:
Is there anything in any of the interfaces to Integer that will allow
me to quickly find the highest bit set in an Integer?
Well, you could use testBit, which is pretty efficient,
But testBit tests only one bit at a time. To prove
On Dec 3, 2007 9:32 PM, Sterling Clover [EMAIL PROTECTED] wrote:
if all else fails, be determined by unpacking it
into the primitives, which are (# Int#, ByteArr# #) with the Int# as
the number of limbs of the integer, as well as its sign.
That's the answer I'm looking for, thanks.
--
Dan
On Dec 3, 2007 10:05 PM, David Benbennick [EMAIL PROTECTED] wrote:
Could you please post your code here when you're done? I'd be
interested to see the final result.
This is just experimental code I'm playing with in order to implement
exact real arithmetic, so there'll never be a final result
There's a bit of work required to make this code good enough for
general consumption, and I don't know much about Haskell internals.
(1) What is the official way to find the size of a word? A quick
look at 6.8.1's base/GHC/Num.lhs reveals that it uses a #defined
symbol.
(2) Is it safe to assume
On Dec 10, 2007 4:51 AM, Daniel Fischer [EMAIL PROTECTED] wrote:
Am Montag, 10. Dezember 2007 10:36 schrieb Ketil Malde:
Daniel Fischer [EMAIL PROTECTED] writes:
Various other people write:
... lots of talk about monads and IO ...
When someone comes to me and says I have this Python
On Dec 10, 2007 11:00 AM, Henning Thielemann
[EMAIL PROTECTED] wrote:
Does Haskell need quickdirty hackers?
The question isn't Does Haskell need quickdirty hackers? It's
would we get better software (using your favourite metric) if we put
Haskell into the hands of quick and dirty hackers?. I
On Dec 14, 2007 12:12 PM, Andrew Coppin [EMAIL PROTECTED] wrote:
Today, with a few import statements and compiler switches, the
exact same code takes 0.05 seconds. Tomorrow, who knows? Maybe I'm being
overly optimistic, but... ;-)
There have been some great improvements in array handling
I have a situation where I have a bunch of lists and I'll frequently
be making new lists from the old ones by applying map and filter. The
map will be applying a function that's effectively the identity on
most elements of the list, and filter will be using a function that
usually gives True. This
Dupont asked:
do you know Nomic?
It's a fabulous and strange game where you have the right to change the rules
in the middle of the game!
I know nomic, but as has been pointed out, it's too wide-ranging to be
captured in Haskell. So how about a game played in the Haskell type
system where
On Thu, Apr 15, 2010 at 4:58 PM, Ashley Yakeley ash...@semantic.org wrote:
type Board a b c d e f g h i =
Either (Three a b c)
(Either (Three d e f)
(Either (Three g h i)
(Either (Three a d g)
(Either (Three b e h)
(Either (Three c f i)
(Either (Three a e i)
(Either (Three c e g)
On Tue, Aug 3, 2010 at 2:51 PM, aditya siram aditya.si...@gmail.com wrote:
I am doing an Intro To Monads talk in September [1].
...what would you stay away from.
Some things to stay away from:
http://byorgey.wordpress.com/2009/01/12/abstraction-intuition-and-the-monad-tutorial-fallacy/
'Point free' is standard mathematical terminology for nothing more
than the style of defining functions without making direct reference
to the elements the functions act on.
This style is exemplified by category theory and the reason it's
called 'point free' rather than 'element free' is that
On 12/2/06, Chris Kuklewicz [EMAIL PROTECTED] wrote:
Grady Lemoine wrote:
I've been playing around with Dan Piponi's work on automatic
differentiation...
I played with such things, as seen on the old wiki:
http://haskell.org/hawiki/ShortExamples_2fSymbolDifferentiation
I missed this while I
On 12/20/06, Bernie Pope [EMAIL PROTECTED] wrote:
(Since learning Haskell, I can now count in Spanish! See:
one in Spanish,
...
Ashley Yakeley) in Spanish
I notice you're using the assumption that Spanish is a Monad so that
Double Spanish can be mapped back into Spanish.
Magnus Therning asked:
but how do I go about creating a finite list, e.g. a list that ends as
soon as 'q' is pressed?
A slightly different approach that doesn't use anything unsafe:
What you want is to return something like an IO [Char] but it needs to
be able to interleave IO. A list of
On 1/23/07, Yitzchak Gale [EMAIL PROTECTED] wrote:
You have written a great explanation of how
ListT works by writing out its definitions in an
interesting way!
I put quite a bit of time into understanding why the old ListT isn't a
monad [1]. But I thought I didn't yet understand the new one.
Yitzchak,
Hmm, I thought it was the old one...
No, definitely the new one. The old one is:
newtype ListT m a = ListT { runListT :: m [a] }
which treats the entire list as one uninterleavable lump.
The new one is:
data MList' m a = MNil | a `MCons` MList m a
type MList m a = m (MList' m
On 1/30/07, Lennart Augustsson [EMAIL PROTECTED] wrote:
Excel is what I like to call a 0:th order functional language,
i.e., you can't even define functions, just values. :)
Every cell with an expression in Excel is a function. The problem is
that the domains and codomains of these functions
On 1/31/07, Lennart Augustsson [EMAIL PROTECTED] wrote:
I think you're using a somewhat non-standard definition of function.
let x = 5
y = x + 2
z = x * y
...
Would you call y and z functions?
Ah...we don't disagree on what a function is, I'm just parsing
spreadsheets
I've always found recursive solutions to problems elegant and I've
always been fed up of people telling me that I should rewrite
recursive solutions iteratively. (Annoying as it is, many people do
that.) I complained about this on K5 and solicited some opinions from
others on whether or not they
dmhouse said:
Hoogle might give me two dozen results when I roughly know the
name of a function, but this isn't what I want.
Agreed. I would *love* to have the interface you propose and I think
it would make a significant difference to the ease of writing Haskell
code.
--
Dan
IOn Feb 11, 2008 9:46 AM, Miguel Mitrofanov [EMAIL PROTECTED] wrote:
It's well known that ListT m monad violates this law in general
(though it satisfies it for some particular monads m). For example,
I went through this example in quite a bit of detail a while ago and
wrote it up here:
Edsko asked:
Is there an intuition that can be used to explain adjunctions to
functional programmers, even if the match isn't necessary 100% perfect
(like natural transformations and polymorphic functions?).
I think there's a catch because many interesting examples of
adjunctions involve
On Mon, Mar 10, 2008 at 3:11 PM, Paulo J. Matos [EMAIL PROTECTED] wrote:
I would like to know if in fact there's any difference in practice
between (), [()], i.e. if in practice the difference matters.
The type [()] is very similar to the type Integer and it's quite
different from () because
2008/3/12 Jed Brown [EMAIL PROTECTED]:
It would be a shame to ...miss the very important point that a
matrix is nothing more than a linear transformation between finite
dimensional spaces.
I rate this obvious seeming fact as one of the most important things
I've learnt about numerical
On Wed, Mar 12, 2008 at 2:33 PM, Andrew Coppin
[EMAIL PROTECTED] wrote:
Hanging around here, you really feel like you're at the cutting edge
of... something... heh.
Another approach isn't to target a CUDA back end for Haskell but to
write an array library that builds computations that can
On Fri, Mar 14, 2008 at 11:50 AM, Andrew Coppin
[EMAIL PROTECTED] wrote:
Haskell has an expressive and powerful type system - which I love. It
also has a seemingly endless list of weird and obscure type system
extensions...And yet, none of this happens in any other programming language
I've
On Tue, Apr 1, 2008 at 2:07 PM, PR Stanley [EMAIL PROTECTED] wrote:
All you'd have to do is to give the inner most function the highest
precdence
What's the innermost function in f g x here?
test :: (a - b - c) - a - b - c
test f g x = f g x
--
Dan
Andrew asked,
...so it's a kind of choice operator? Run all actions until you get to one
that succeeds and return the result from that?
The eternal bit of trickiness for Haskell is that type classes group
often together things that people don't immediately see as similar -
monads probably
Miguel said:
Well, that's the whole point of mathematics, isn't it?
Abstraction is common to mathematics and computing. But in computing
the abstraction often follows lines that seem obvious. For example a
GUI library might have a Widget class and people can immediately
identify various regions
On Sat, May 10, 2008 at 7:20 AM, Neil Mitchell [EMAIL PROTECTED] wrote:
Jurriaan Hage and Stefan Holdermans. Heap recycling for lazy
languages. In John Hatcliff, Robert Glück, and Oege de Moor, editors,
_Proceedings of the 2008 ACM SIGPLAN Symposium on Partial Evaluation
and
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