e more economic to "jump".
This is as simple as that.
Jerzy Karczmarczuk
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ome dozen smileys...
More seriously, some people like exquisite continuations and will use
them. Instead of fighting against exceptions it might be more fruitful
to make them more robust, powerful, parametrable and sexy.
Jerzy Karczmarczuk
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Kim-Ee Yeoh comments my reading suggestion:
"Indiscrete Thoughts" by Gian-Carlo Rota, published by Birkhäuser
in 1997. Available on the Web. [I forgot where]
I'm rather fond of Rota's two volumes of musings. For the purpose of
furthering the quality of philosophizing, would it not be
d find
them interesting. And you will find inside that for Rota the term
"should" is very important, even if it impossible to define...)
Many thanks to Olivier Danvy, who recommended me this book!
Jerzy Karczmarczuk
Caen, France.
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I am sorry for having mixed-up arguments (but who throws the first
stone?...)
Jerzy seemed to suggest that the "impurity" of IO was somehow related to it
not supporting very many operations.
No, not really. I added
First, it is not true that you can do with, say, (printStr "Ho!" )
whatever
reasonable sense.
Would you add to all this:
getLine == getLine
etc.?
Good luck!
I suspect that you would have to establish also the equality relation
between functions and between infinite streams.
And you would end as Giordano Bruno and Jeanne d'Arc. But for diffe
...).
The "running" or "execution" takes place outside of your program. In
such a way Richard O'Keefe and I converge... That's why I say that the
concept of purity is meaningless in the discussed context. It is a kind
of counterfeit notion,
for me the "purity" (while teaching I try to avoid this word)
means simply that whatever you do with the object, it won't fire a
"magic" process. As Richard, I do not claim that this is "right", but it
surely facilitated my teach
some layers UNDER the one YOU control) are impure, since
there is no operational definition of purity for them. "No side
effects"? Sure, if you don't do anything with it. Even the most horrible
Devil is pure. Unless you call it...
Jerzy Karczmarczuk
_
Le 06/08/2013 11:01, J. Stutterheim a écrit :
... So in reply to Jerzy, I do want to encourage the discussion in the "Noble Domain
of Philosophy" and I also want to repeat that I am not proposing to change Haskell
or Haskell libraries
Jurriën, I taught Haskell for several years. I saw the dis
ith all my respect, I see that Haskell reached finally the Noble Domain
of Philosophy. I mean, instead of discussing concepts, people begin to
discuss names.
And since for some, even IO () is a "pure" value, I suspect that the
next round will rekindle the discussion on
Le 09/07/2013 13:53, Tom Nielsen a écrit :
Almost everything else -- optimal decisions, categorisation, (...) --
becomes trivial.
Optimal decisions "trivial"?
Interesting... And not so frequent...
Jerzy Karczmarczuk
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e, and the rest of the community, that
Haskell will always spiritually remain the same clean,
consistent programming language as it is now!
Yes.
Dear Mom, dear Dad! Promise me that you will never die...
I wish that for all of you.
Jerzy Ka
obscure, even if one
"almost-syntax" error was clear...
Jerzy Karczmarczuk
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n.
Perhaps it might help to know what do you need it for...
The best
Jerzy Karczmarczuk
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Le 17/04/2013 01:48, Jerzy Karczmarczuk a écrit :
With constant acceleration v=v0+a*Dt => 1.01, not 1.05
Gosh, trivial errors seem to be contagious. Of course I meant 1.1, not
1.01. Sorry. JK
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ysics is
simply wrong.
==
In general, even correcting all, you might have reasonable results in
some trivial cases, but in general the extrapolating Euler schema is
unstable, produces growing errors (e. g. in the oscillating case).
Jerzy Karc
f the representation.
Jerzy Karczmarczuk
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ans more learning ab
ovo, the loss of time might be considerable.
Roman: - Christopher Howard seems to be very far from publishing papers;
he asks us whether he should complete his B.S. In this context,
recommending Open Source seems a bit p
Le 29/08/2012 23:55, Henk-Jan van Tuyl a écrit :
In conclusion: repeating the same thing could give different results.
Certainly!
My favourite example is : sex.
Jerzy Karczmarczuk
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http
use a different random generation
protocol, or whatever. I believe that this solution is known for years...
Jerzy Karczmarczuk
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ving replaced the recursion by
explicit stacks + loops.
Jerzy Karczmarczuk
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Le 26/03/2012 16:31, Chris Smith a écrit :
If you were
asking about why there is no ring on [a] that defines (+) = zipWith
(+), then here's why. By that definition, you have [1,2,3] + [4,5] =
[5,7]. But also [1,2,42] + [4,5] = [5,7]. Addition by [4,5] is not
one-to-one, so [4,5] cannot be inve
Le 26/03/2012 02:41, Chris Smith a écrit :
Of course there are rings for which it's possible to represent the
elements as lists. Nevertheless, there is definitely not one that
defines (+) = zipWith (+), as did the one I was responding to.
What?
The additive structure does not define a ring.
Th
than lists,
is a question of style. The fact that - as you say - "there's no good
way to write an instance that obeys the laws" won't disturb my sleep.
You know, there is no good way to organise a society where everybody
obeys the Law. This is no argument against the organis
:set
-XFlexibleInstances .
(Then you might have some other "small" problems, but nobody is perfect).
Jerzy Karczmarczuk
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l class with division), and
that's it. You cannot compute the exponential [using the standard name]
of a power series, unless you declare this series, which may be a list
of rational coefficients, a "Floating".
Thank you.
Jerzy Karczmarczuk
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WHICH *GOOD* REASONS??
Thank you.
Jerzy Karczmarczuk
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n Haskell,
disguised as a do block. There are two "distinct" file objects, the
"previous", and the "next" one, which happen to share the same name,
because *the type system* prevents that a computing block refers to
both. Either the old, or the new.
This is my phil
transparency, or does it?
Jerzy Karczmarczuk
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in to 2-nd year students what does it mean: a
value which doesn't have a value...
Thank you.
Jerzy Karczmarczuk
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Aleksey Khudyakov:
On 09.02.2012 15:32, Jerzy Karczmarczuk wrote:
1. Mersenne Twister, AND congruential generators AND the Marsaglia
stuff, all use some kind of "seed", all are stateful. There are no
miracles. Just look the agressive monadization, the form of defaultSeed,
etc. wit
o all people who made those generators however imperfect
they are. Only Mister Nobody is perfect.
Jerzy Karczmarczuk
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Conal Elliott cites Steve Horne:
I look at this World parameter as purely hypothetical, a trick
used to gain an intuition. Whereas Jerzy (I think) uses it to
claim Haskell is referentially transparent - those differing x and
y values come from different worlds, or different world
.
Sorry, what are you trying to suggest?
You show two OBVIOUSLY different pieces of code, and you say that they
are different.
If, by chance, some newbie reads that and gets the impression that (<-)
is something equivalent to (=), you are serving the devil.
J
Yves Parès :
all standard Monads are newtypes wrapping functions
What about Maybe and [] ?
Jerzy Karczmarczuk
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Bardur Arantsson:
Random streams are not referentially transparent, though, AFAICT...?
Either way this thread has gone on long enough, let's not prolong it
needlessly with this side discussion.
Sure.
But the discussion on randomness is /per se/ interesting, especially in
a functional settin
ither way, at run-time, Haskell is impure.
Most people here, some VERY knowledgeable, do not agree with you.
/Errare humanum est, perseverare diabolicum/.
Either way, since you insist to prove that you DON'T WANT to understand
other people view, I wish you good luck.
Jerzy Ka
Steve Horne :
Some code (intended to be loaded into GHCi and played with)
-- import System.Random
-- randSelect "this is a list" 5 (mkStdGen 9877087)
-- ...
module P23 (randSelect) where
-- ...
randSelect' (x:xs) n l g = let xsLen = (l - 1)
Steve Horne :
I only meant that there's random number handling support in the
Haskell library and, and least judging by type signatures, it's pure
functional code with no hint of the IO monad.
Look well at those functions, please.
Within the RandomGen class you have pure members, such as next
The story begins here:
Steve Horne:
/BTW - why use an IO action for random number generation? There's a
perfectly good pure generator. It's probably handy to treat it
monadically to sequence the generator state/seed/whatever but random
number generation can be completely pure. /
===
Le 29/12/2011 18:01, Iustin Pop a écrit :
I'm confused as what you mean.
And to clarify better my original email: yes, (bar x) always gives you
back the same IO action; but the results of said IO action are/can be
different when executed.
The whole of my point is that it DOESN'T MATTER. (And I b
tion. Then, the
discussion might be more fruitful
Jerzy Karczmarczuk
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ution operator transformed both of you, YOU and the particle into a
new instance of this sector.
OK, I stop here, otherwise the digestion of your sandwiches may produce
some side effects.
Jerzy Karczmarczuk
Caen, France.
(William the Conqueror was here. Produced one nice side-effect.)
u disagree, show them.
I don't think that speaking about "compile-time purity" is correct.
Jerzy Karczmarczuk
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Dear Gurus,
A.
Why the Haskell Platform is still based on ghc 7.03?
(At least on WinXP)
B.
Does anybody care about wxHaskell?
Thanks.
Jerzy Karczmarczuk
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sly choose those who will implement them.
Jerzy Karczmarczuk
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of why
each one behaves the way it does" of David Fox, I compare it with a
question of a young army officer, addressed to his elders:
"Tell me how to win the war in the quickest way possible, rather than
boring me with the explanations behind all those complicated strategies&
nual-ocaml/manual003.html#toc11
OK, these are not slides...
Jerzy Karczmarczuk
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what is strictly forbidden, is lazily allowed.
Best regards
Jerzy Karczmarczuk
Caen, France.
(25 km from the Oldest Comic Strip in the World, 1000 years and progressing)
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cannot
be really sorted. Especially with "sortir" in French. BTW, "to sort" in
English is "trier" in French; "tri", "trie", "tree". Try everything...
==
When some years ago we asked our students to write some reports in
English, I t
o there is no problem in
"handling" those infinite modules. It will just take you an anfinite
amount of time before you get any money from such a work. But this is a
general problem elsewhere as well.
Jerzy Karczmarczuk
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Peter Simons :
Now, a person who has profound knowledge of the subject you're asking
about is not very likely to do this, because he is probably not going to
learn anything in the process. Dedicating time and effort to studying
your particular problem is not an appealing prospect.
You might be r
t you don't need the
details).
Jerzy Karczmarczuk
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a fool, I didn't look at the stars... (Well, actually
I was a fool, but it is a long story).
Jerzy Karczmarczuk
Caen, France
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may manifest itself when you specify the
*instances*.
That's why I suggested how you might do that: for some datatypes, say
the Emperors, you specify some special flying method (e.g. dummy or
bombing), or you don't specify it at al
really don't need it...
When instancing your Bird class you may "forget" to define the flying
methods.
Is this unsuitable for you? The compiler will yell, but this is harmless.
Jerzy Karczmarczuk
PS. Penguins DO fly.
http://www.telegraph.co.uk/news/worldnews/1583517/Flying-
by Planet Math, integrated into Drupal, etc.
I confess I tried to write something which displayed math fromHaskell, I
gave even a project of that kind to my student. But the solutions exist
already and are known, so...
See e.g.
http://www.twingly.com/haskell/stories/4013ffd773e942fdb4b9cf2cb
quot; in Python. This is not just a
non-deterministic return mechanism, but an expression, which yields a
value also for the generator code. It becomes thus a reentrant
co-procedure, which goes quite a mileage beyond the lazy list model.
Jerzy Karczmarczuk
_
engine. Perhaps, if we had
before a semester of OpenGL, and at least two months of a true
course/tutorial (not your pseudo-tutorial on the Web...) we could be
more productive.
That's it...
I don't want to generalize, but there is a huge work to do
itely
progressing, such as the standard definition of the stream of integers,
used to scare the beginners...
ints = 1 : zipWith (+) (fix (1:)) ints
where fix f = f (fix f)
Thanks.
Jerzy Karczmarczuk
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laziness?...
Jerzy Karczmarczuk
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l
tricks.
Yep.
But, BTW, could you tell me what was the result of the final desugarization
and the BASIC sense of the IO monad for you?
Jerzy Karczmarczuk
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countries...)
Somebody finally decided to ridiculise the system. If you want a good laugh,
see the patent 6,368,227. The search site is here:
http://patft.uspto.gov/netahtml/PTO/srchnum.htm
Best regards.
Jerzy Karczmarczuk
PS. concerning the patent 7120900. The authors appropria
NOW
for its evolution have other priorities. But the story has at least 15
years. Jeroen Fokker did something then, I worked on it at the same
period. Now Jacques Carette has his own system, and Sergey Mechveliani
another one...
But other people don't care, s
no addition or (*)seem
natural. Or the other way round ; apparently Sönke Hahn is in that
situation, so he fakes...
Jerzy Karczmarczuk
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ansform ANY
parameter into something unrecognizable). When he says : "I know all that",
THEN hurt him badly with monads.
Jerzy Karczmarczuk
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ve they spent teaching
parallel programming?
I suggest that you say goodmorning to Google.
Jerzy Karczmarczuk
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o do it
dynamically, then, either you know how to interrupt *any* infinite process
within Haskell, or you have to learn how to do it... Here people more
competent than myself will surely help you. Good luck, and thanks for
your interest in a this fabulous fie
hrough the truncation of real randoms?
Jerzy Karczmarczuk
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So, why not use
'randoms' to generate an infinite list of them, 'take' some N, and then
'sum' 1 on randoms filtered by the circle condition. I think that you
won't need full 10 lines of code...
Jerzy Karczmarczuk
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thematical subsumptions, e.g., that the ring of
integers modulo N becomes a field if N is prime. Or, that every additive
group is a module over integers. But it seems that we are very far from
such a dream.
Jerzy Karczmarczuk
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er to write a new Prelude. :-)
Oh, yes, our common dream...
Jerzy Karczmarczuk
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Hans Aberg writes:
...
But one should also be able to write (f+g)(x). - This does not work in
Haskell, because Num requires an instance of Eq and Show.
So, declare them, even if they are vacuous. I did it several times, I am
still alive, so no need to say "this does not work"
pe t, it is g(g x), not (t->t), it is as
simple as that. Perhaps you didn't recognize that "->" is syntactically
a right-associative op, so
a->b->c is equivalent to a->(b->c), or
(t->t)->t->t equiv. to (t->t)->(t->t)
Jerzy Karczmarczuk
ement that f g x fails. It doesn't, in normal order everything
should go smoothly, f g 5 returns 5 = (f g) 5 = g 5, unless I am
terribly mistaken...
Where did you see an error?
Jerzy Karczmarczuk
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://www.thefreecountry.com/compilers/prolog.shtml
You will find there the GNU-Prolog, whose licensing should be as
you wish.
Jerzy Karczmarczuk
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ctor Classes"
by Luc Duponcheel, and Erik Meijer. Available through citeseer.
This has been written under Gofer, should thus work for Hugs, and
no reason why not under GHC.
Very nice paper. (Of course, Rydeheard and Burstall is their first
reference
ng against (apart an auxiliary list, and "x" not curried away)
times n f x = (iterate f x)!!n
Jerzy Karczmarczuk
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re or less the same as between "Immediate failure" and "Delayed
failure". Choose yourselves which is which.
Jerzy Karczmarczuk
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s represented. If the numbers are
normalized, as they should, plenty of low-level iterative algorithms
may use the equality - after some operation - to check that the machine-
precision convergence has been obtained. On the contrary, the verification
that the absolute value between two ter
such packages in the numerical domain, typically don't believe that FP
gives anything interesting. At least, this is the opinion of physicists
I spoke to recently.
Never mind. We shall dance over their cadavers, unless they dance over
ours. In both cases we shall be happy.
Jerzy Karczmarczuk
Yitzchak Gale writes:
Jerzy Karczmarczuk wrote:
Would you say that *no* typical floating-point software is reliable?
It depends on how you define "reliable".
Floating point intentionally trades accuracy for speed,
...
It used to be true - and may still be - that the eng
ng it
different ways will give you different answers. This is *not* a good
way to write reliable software.
[Then we see the scalar product whose value *may* depend on the ev. order]
I wonder...
Would you say that *no* typical floating-point software is reliable?
Jerzy Karczma
.
There is a small obscure religious sect of people who want to implement
several mathematical entities as functional operators, where multiplication
is f. composition. You do it too generically, too optimistically, and then
some octonions come and br
onacci of 42, then you have to wait so long, that you must build a
special Supercomputer for it. It has, BTW. been built, and it is called
the "haskell-cafe mailing list".
Jerzy Karczmarczuk
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widely known entre a gente falando portugues.
Vou calar a boca...
Gomen nasai.
Jerzy Karczmarczuk
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e where I sit now...
Arigato gozaimasu.
Jerzy Karczmarczuk.
PS. If you think that "arigato" is a genuine Japanese word, well, check
how the appropriately translated word is spelled in Portuguese...
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Haskell
Tim Chevalier(*) writes:
I think to ease the acceptance of Haskell in the broader world, we
should just change the name to Schönfinkel.
On the other hand, is better not to try Curry, since the French pronounce
it: Queue-rhrhrh. This is for me absolutely inacceptable and scandalous,
since t
you should take into account
that no word may terminate on a consonant, so you have to add another
schwa, or a Sicilian Variant of that at the end.
Jerzy Karczmarczuk (pronounced as written)
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any other conceptual structure, can be
stored and communicated. You may kill all the "working instances", and
rekindle it later. It such a way it is difficult to kill a religion, or
a political doctrine. But it may die, become useless/unused tempora
. This "School of computer science" gave some
theory to the humanity. But no, or almost no software, sorry. I *sincerely*
hope that it changed now.
Jerzy Karczmarczuk
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ia and their satellites became
a kind of desert here not only because of economical problems...
Jerzy Karczmarczuk
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l
targeted at serious comp. sci. problems, and I think that the fact
that somebody is young and inexperienced, is not a justification to make
false claims, just because this and that had XXX years less than myself in
order to read some easily available texts. Of course, anybody may say
"dubious truths
ss'
sake!?
Jerzy Karczmarczuk
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s you gratuitously with a waste of
time. Absolutely inacceptable for engineering reasons. In games it might
happen as well, when, e.g., a collision handling module finds a pathological
geometrical situation, with a singularity so close that math bombs. Then,
a possible solution is
stupid than you.
http://mathworld.wolfram.com/Undefined.html
http://en.wikipedia.org/wiki/Defined_and_undefined
http://mathforum.org/library/drmath/view/53336.html
http://encarta.msn.com/encyclopedia_761568582/Calculus_(mathematics).html
etc.
Jerzy Karczmarczuk
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ish... But don't write medical software, please...
Jerzy Karczmarczuk
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racters.
I perhaps misunderstand this phrase, but if you suggest that it would be
useful to snatch the code examples from within the book, I believe that
no OCR is needed, they are here:
http://www.iro.umontreal.ca/~lapalme/AlgoFP/code.html
things more regular!
Sometimes it is useful, but not where it "for free" gives you more
opportunities to make bugs.
I wonder whether
f = g
and
f x = g x
attributes *always* the same type to both variants of f...
Jerzy Karczmarczuk
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