Carl Witty wrote:
On Mon, 2007-10-22 at 10:54 -0400, Brent Yorgey wrote:
The Online Encyclopedia of Integer Sequences should really
contain more
Haskell code for describing the sequences.
Agreed! I propose an OEIS party where we all sit around one day and
[EMAIL PROTECTED] wrote:
But... tell me please, ANYONE, who takes part in this inspiring exchange:
How many COBOL programs have you written in your life?
How many programs in Cobol have you actually SEEN?
Shudder. In '86, I had to modify a COBOL code generator, *written in
COBOL*. The
Stephen Tetley wrote:
The finally tagless style is an implementation of the TypeCase pattern
(Bruno C. d. S. Oliveira and Jeremy Gibbons):
One part of our work does that, yes.
The authors of the Finally Tagless note in the long version of their
paper that the GADT TypeCase had some
Günther Schmidt wrote:
In Olegs haskell implementation he is using classes mainly to model
the syntax and instances to use for evaluators / compilers to allow
multiple interpretations.
When there are 3 authors on a paper (and in the implementation file), it
is customary to acknowledge all 3,
Don Stewart wrote:
I think we don't see as much metaprogramming because of other language
features -- laziness, operator syntax, and type classes -- make a bunch
of common designs work without needing metaprogramming.
While true, there are also 2 other reasons for meta-programmers are not
Jason Dagit wrote:
While true, there are also 2 other reasons for meta-programmers
are not all over Haskell:
1. efficiency nuts are already using C++ templates and don't see
why they would switch,
2. people who care about types use a typed meta-language (like
Casey McCann wrote:
Not to speak for Jacques,
:-)
and then you followed that up with a post with which I fully agree.
Jacques
but my impression is that while TH itself is
typed--it's just more Haskell after all--it doesn't do much to prevent
you from generating code that is not well-typed.
One thing I should have mentionned - TH and camlp4 are really
equivalents. And camlp4 is as-typed-as TH (or not, depending on your
point of view). I am co-author of a camlp4 extension, and I must admit
that coding in camlp4 was not enjoyable, while coding in metaocaml
(eventually) is.
[I
I have heard generic programming described tongue-in-cheek as the kind
of polymorphism that a language does not (yet) have. I find this
description rather apt, and it matches fairly what I see called
'generic' in various communities. But who said this, where and when?
Jacques
Bradford Larsen wrote:
On Tue, Apr 27, 2010 at 4:23 PM, Jacques Carette care...@mcmaster.ca wrote:
I have heard generic programming described tongue-in-cheek as the kind of
polymorphism that a language does not (yet) have. I find this description
rather apt, and it matches fairly what I
Sterling Clover wrote:
I first encountered this quip on ltu:
http://lambda-the-ultimate.org/node/1926#comment-23411
However, that comment doesn't give a source either.
Probably where I remembered it from too. I'll continue searching - it's
a good quote!
Jacques
Bradford Larsen wrote:
I don't have the book handy (it was from the library), but I seem to
remember reading something along those lines in ``Datatype-Generic
Programming: International Spring School, SSDGP 2006, Nottingham, UK,
April 24-27, 2006, Revised Lectures'', edited by Backhouse,
Mike Dillon wrote:
begin Ivan Lazar Miljenovic quotation:
I take it you haven't had the legal problems that DrIFT had when it used
to be called Derive? http://www.dcs.gla.ac.uk/~nww/Derive/History.html
Looks
like they stopped selling it in June 2007, at least in the UK:
[I work with Gordon on this]
The problem domain is test frameworks, more specifically
proposition-based testing. We are most of the way through unifying
QuickCheck and SmallCheck (as well as untangling the various 'stages'),
and are now generalizing.
The generator is obvious. The 'reducer'
Excellent answer! Splitting the Symantics class into pieces is one of
the techniques that we didn't need for solving the original problem
(tagless partial evaluation without resorting to fancy types) that set
us on this track. Which is too bad, because it would have made a nice
addition. The
Günther Schmidt wrote:
I have recently found something new that might also prove to be useful
for EDSLs.
http://blog.sigfpe.com/2009/05/three-projections-of-doctor-futamura.html
Dan's blog post doesn't give any code or implementation but in a way
it tackles the same problem, and since you
[See comments at bottom]
Bulat Ziganshin wrote:
Finally i've implemented the following (you then would use
'withForeignPtr' to work with contents of ForeignPtr):
-- -
-- Encode/decode contents of memory buffer
You would need to define a type class
(Binary a) = EncodedPtr a b
where the 'a' is as you have it currently, and the b would be an
enumerated type which tracks the memory representation.
I agree they are different concepts - that is why an EncodedPtr would
require 2 type parameters. Of
I have no problems with marshalling/unmarshalling (and even with the
implicit casting going on). What I dislike is having a bunch of
functions which are the same but with different names, where the
difference boils down to enumerated types that end up being encoded in
the function name.
Bulat Ziganshin wrote:
i'm not against your idea, you absolutely right that this will be more
Haskell way, but can this be implemented without additional
complications for library users?
C is a language which pushes the boundaries of no complications (ie
convenience) quite far (and yet
Your solution would imply[1] that all Rational are multiplicatively
invertible -- which they are not.
The Rationals are not a multiplicative group -- although the _positive_
Rationals are. You can't express this in Haskell's type system AFAIK.
Your basic point is correct: if you are willing
David Menendez wrote:
* Having (+) work on lists, tuples and all the other monoids would
make error messages more complicated.
It gets worse than that. Imagine trying to explain to someone why 1 +
sin is actually \a - const 1 a + sin a.
It isn't that hard - it is done routinely in
[EMAIL PROTECTED] wrote:
That is what polymorphism is all about!
Not in this context, sorry. This is a convention. Another one may give
you
an abomination, e.g., 1+sin means 1 plus the addres of the sin routine.
(Of course not in a 'decent' language, but I know a few undecent.
No, it is
Whenever people start discussing the Numeric type classes, the true
scope of what a refactoring can (and should?) be is frequently
under-estimated. The 'structure' of algebraic objects in mathematics
has been studied quite a lot (in mathematics and in CS, but not so much
by programming
Greg Buchholz wrote:
I guess it just looks really strange to my eyes. For example, foo
and bar are legal, but baz isn't. That's what I was thinking of the
situation, but I guess the type classes iron out the differences.
foo :: Int - Int - Int - Int
foo 0 = (+)
bar :: Int - Int - Int
Robert Dockins wrote:
Or how about ??
lookupVarible target env =
case [ v | (n,v) - env, n==target ] of
(x:_) - x
_ - assert False $ BUG: Unexpected variable out of scope
++(show target)++ in environment ++(show env)
Other have pointed out that, in the CURRENT Haskell
David Roundy wrote:
The trouble is that your solution doesn't allow you to use do-notation with
the IxMonad. And if you did allow yourself to use do-notation by rebinding
(=), etc, then you wouldn't be able to use ordinary monads with
do-notation in the same module. That's what makes things
[As recently seen on LtU - http://lambda-the-ultimate.org/node/1919] An
amazing paper
http://www.dbmcintyre.pwp.blueyonder.co.uk/index_f/menu_f/j_f/apl95.pdf
on composition as seen from APL and J. The terminology (using verbs,
nouns, adverbs, etc) is _so_ much more evocative than the
First, I believe that this paper
http://homepages.inf.ed.ac.uk/ratkey/param-notions.pdf
is intimately related to WitnessMonad.
David Roundy wrote:
Rebinding the do notation is at least reasonably clean, it's just that we
don't want to lose the ability to mix with ordinary monads.
This
Lennart Augustsson wrote:
I must second this opinion. There's this (false) perception that you
need all
kinds of extensions to make Haskell usable. It's simply not true.
Certain
extensions can make your life easier, but that's it.
To write code in Haskell, this is true.
However, one of
Neil Mitchell wrote:
In other words, you can program in Haskell just fine without
extensions. But if you want that next level in type safety,
extensions is where it's at, at least for the kind of code I write.
What level of safety do these type extensions give you?
Check out many, many, many
Yes, dependent types have a lot to do with all this. And I am an eager
lurker of all this Epigram.
Scott Brickner wrote:
Jacques Carette wrote:
Array out-of-bounds, fromJust, head on an empty list, and
pattern-match failures are in my list of things I wish the type
system could help me
Brian Hulley wrote:
Would it be possible to augment Haskell's type system so that it was
the same as that used in Epigram?
No, no! Epigram is a wonderfully pure research experiment in one corner
of the design space. The corner it is exploring is not particularly
Haskell like, though the
Tim Newsham wrote:
I have to write:
do {
x - getSomeNum
y - anotherWayToGetANum
return (x + y)
}
even if the computation of x and y are completely independant of
each other.
I too have really missed a parallel composition operator to do
something like the above.
There is a Maple plug-in for Excel. If you have Maple (on Windows),
just start Excel and you'll see extra buttons.
This allows you to have cells containing symbols, as well as access to
all of Maple's functions. This easily gets you a (very impure!)
higher-order functional language
If I have a class, say
class Symantics repr where
int:: Int - repr Int
and so on, I would like to *require* that 'repr' be covariant. Is there
any way to do that?
Jacques
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Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
Since my last query was answered so quickly, let's try another.
I have looked on Hoogle. I would have asked Djinn, but I don't have it
around. So, can someone find a term that inhabits
(forall a. a - b) - (forall a. m a - m b)
? I think of this as the type of functions that, given a
in a journal; papers from both PLMMS 2007
and 2008 will be considered here (details to follow).
Programme Committee
---
Jacques Carette (Co-Chair) (McMaster University, Canada)
John Harrison (Intel Corporation, USA)
Hugo Herbelin (INRIA, Ecole polytechnique
I think HOPS is what you are looking for
http://www.cas.mcmaster.ca/~kahl/HOPS/
It may advertize itself otherwise, but the main thing you 'see' when
running programs in fully explicit mode is exactly all the graph reductions.
Jacques
___
Reasoning.
There will be a separate submission and review phase for this, where
papers from both PLMMS 2007 and 2008 will be considered.
Programme Committee
---
Jacques Carette (Co-Chair) (McMaster University, Canada)
John Harrison (Intel Corporation, USA)
Hugo
You can translate the following algorithm (written in Maple 11), which
can be made purely functional. [For the cognoscenti: attributes are
implemented in-place in Maple, but that is really just an instance of
the Decorator pattern which can be just as easily implemented with a
functional
for this, where
papers from both PLMMS 2007 and 2008 will be considered.
Programme Committee
---
Jacques Carette (Co-Chair) (McMaster University, Canada)
John Harrison (Intel Corporation, USA)
Hugo Herbelin (INRIA, Ecole polytechnique, France)
James McKinna
Claus Reinke wrote:
You might find this interesting:
@inproceedings{ fokker95explaining,
author = Jeroen Fokker,
title = Explaining Algebraic Theory with Functional Programs,
booktitle = Functional Programming Languages in Education,
pages = 139-158,
year = 1995,
url =
apfelmus wrote:
Grzegorz Chrupala wrote:
split DOC . words . map toLower = (:[]) . words . map toLower
Since you converted everything to lowercase, the string DOC will
never appear in the text, resulting in a single huge document.
Oops, that should have been obvious, sorry for the dumb
Lennart Augustsson wrote:
Everyone agrees that the Haskell numeric hierarchy is flawed, but I've
yet to see a good replacement.
That's because the good replacement which is mathematically sound
would be a real mess to work with -- for exactly the same reason that
Functor , Applicative and
It's possible, but it's not nice. You need to be able to get out of
the monad to make the types match, i.e.
lam f = I (return $ \x - let y = I (return x) in
unsafePerformIO $ unI (f y))
The use of IO 'forces' lam to transform its effectful input into an even
, that is disappointing in some way, guess I still have a lot to
learn.
Günther
Am 05.10.2009, 18:06 Uhr, schrieb Jacques Carette care...@mcmaster.ca:
It's possible, but it's not nice. You need to be able to get out of
the monad to make the types match, i.e.
lam f = I (return $ \x - let y
(sorry for the slow reply on this topic...)
Robert Atkey and Oleg presented some very interesting code in response
to your query. But some of you might (and should!) be asking why on
earth did Jacques use unsafePerformIO?, especially when neither Robert
nor Oleg did.
Simply put: I answered
Just a short note to show how the 3 evaluation orders can be written in
a very symmetric manner:
o...@okmij.org wrote these as:
In call-by-name, we have
lam f = S . return $ (unS . f . S)
In call-by-value, we have
lam f = S . return $ (\x - x = unS . f . S . return)
In
I'd like to ask the cafe's advice on how to 'do this right'.
The situation is that we've got 2 literate Haskell programs which we
would like to refactor. In fact, this refactoring will ultimately unify
these 2 separate programs into a single framework. Every refactoring
step is well-defined
I just downloaded a fresh copy of Haskell Platform, and successfully got
cabal to update itself. I installed smallcheck-0.4 successfully too.
But then I tried to install lhs2tex, which 'worked' until the point of
saying:
Linking dist\build\lhs2TeX\lhs2TeX.exe ...
Installing executable(s) in
Which is 'right' in a way, since in the language Conor defined, all
definable terms are infinitely differentiable, and that can be
inferred from the given rules. That, in practice, you only need a
finite number of them in any given computation is derivable from the
instances, but is not a
Stephen Tetley wrote:
Hi Jacques
Does it install properly by the runhaskell Setup.hs configure / build
/ install? I re-installed it this way a couple of weeks ago and it
never mentioned mktexlsr.
No, it doesn't. I first run into issues with exceptions-related issues
(as you did), which I
Some success now.
Reverting to building by hand, if I
1. edit config.ml to put quotes around the name of the GHC executable
(since it contains spaces AND () ),
2. edit Makefile to add -package base-3.0.3.1 on to the --make line,
things proceed through the build and install stage properly.
Günther Schmidt wrote:
My guess is that finally tagless style allows one to create a syntax
without any initial dependency to an implementation. Ie. once one has
created the syntax in this style one can then proceed to construct terms.
Yes.
So this is my goal, create a syntax for relational
Günther Schmidt wrote:
I do know that I could express my algorithms via list-comprehension or
in a List Monad, all using tuples. And that would be concrete and
grossly inefficient.
You should probably tell us what these algorithms accomplish, rather
than how one implementation goes. From a
[I have now subscribed to haskell-cafe]
Henning Thielemann [EMAIL PROTECTED] wrote:
This seems to be related to what I wrote yesterday
http://www.haskell.org/pipermail/haskell-cafe/2005-January/008893.html
Yes, very much. Except that rather than trying to tell mathematicians that they are
[My apologies for not seeing the related discussion yesterday on haskell-cafe,
I was not subscribed until just now]
Iavor Diatchki [EMAIL PROTECTED] wrote:
On Fri, 28 Jan 2005 10:01:33 -0500, Jacques Carette [EMAIL PROTECTED] wrote:
The previous post on record syntax reminded me of some
The recent post of Graham Klyne (below) reminds me that I have meant to ask:
is there a ``top 20'' things a serious programmer should know when writing
code in Haskell? Of course there is a lot of programming language theory
that would be great to know, but I mean really down-to-earth things like
Josef Svenningsson [EMAIL PROTECTED] wrote:
You claimed that monad transformers break the
mzero-is-right-identity-for-bind law because they can be applied to
IO. I say, it's not the monad transformers fault. They cannot possibly
be expected to repair the law if they are given a faulty monad.
Thomas Jäger [EMAIL PROTECTED] wrote:
On Mon, 14 Feb 2005 11:07:48 +0100, Daniel Fischer And could one define
\f g h x y - f (g x) (h y)
point-free?
sure,
((flip . ((.) .)) .) . (.)
That occurence of flip cannot (AFAIK) be removed, indicating that as far as natural composition is concerned,
Were I to write the same code as
Terrence Brannon [EMAIL PROTECTED] wrote:
module Crypt_Discordian
where
import List
vowel_list = aeiouAEIOU
is_vowel c = c `elem` vowel_list
move_vowels lis = move_vowels' lis [] []
move_vowels' [] c v = v ++ c
move_vowels' (x:xs) c v
| is_vowel x =
I tried to implement symbolic differentation using GHC's simplification
rules. I assume that someone has already thought about this, right?
You are trying to do 'intensional programming' via GHC's simplification
rules, ouch! You are likely to hit limits very very quickly.
However, if you
Philippa Cowderoy [EMAIL PROTECTED] wrote:
On Fri, 29 Apr 2005, Simon Peyton-Jones wrote:
2. Use sub-typing, so that a value (Left x) is *both* in type Either
and in type NEither. This opens a very large and complicated design
space, as Ben mentioned.
I've been playing with this design space
There is also Template Haskell vs MetaOCaml.
For the life of me, I still cannot fathom why Template Haskell is untyped, while MetaOCaml is fully typed. Which is
the main reason I write meta-program in MetaOCaml and 'other' programs in Haskell.
There is the additional aspect that my
Duncan Coutts wrote:
On Wed, 2005-05-04 at 18:29 -0400, Jacques Carette wrote:
There is also Template Haskell vs MetaOCaml.
For the life of me, I still cannot fathom why Template Haskell is untyped, while MetaOCaml is fully typed. Which is
the main reason I write meta-program
Jerzy Karczmarczuk [EMAIL PROTECTED] wrote:
Syntax for 3D arrays?
Give me one single language where this is natural and immediate.
I can think of 3: Mathematica, Maple and APL.
But I hope you don't
try to convince us that Mathematica is good at number crunching...
For linear algebra, Maple,
[EMAIL PROTECTED] wrote:
Jacques Carette writes:
Jerzy Karczmarczuk wrote:
Syntax for 3D arrays?
Give me one single language where this is natural and immediate.
I can think of 3: Mathematica, Maple and APL.
I can't see how Maple makes things more *natural and
immediate* than Matlab
Wonderful post! I just want to throw a minor wrench in:
[EMAIL PROTECTED] wrote:
Eq is not merely a function of type a - a - Bool. It's a concept
with semantics. It must be an equivalence relation, and it also must
mean semantic equality. Functions that respect semantic equality have
the
Marcin 'Qrczak' Kowalczyk [EMAIL PROTECTED] wrote:
Jacques Carette [EMAIL PROTECTED] writes:
[EMAIL PROTECTED] wrote:
Eq is not merely a function of type a - a - Bool. It's a concept
with semantics. It must be an equivalence relation, and it also must
mean semantic equality. Functions
Lennart Augustsson [EMAIL PROTECTED] wrote:
Jacques Carette wrote:
Such people have the nasty habit of also thinking that ALL
functions are continuous! You might think they were constructivists or
something.
Why would a constructivist think that all functions are continuous?
It makes
[EMAIL PROTECTED] wrote:
Why do you think that constructivists are against +0 /= -0?
Because they can't prove it - either way.
Or that they think that all functions are continuous?
[See previous email] Because all constructible functions are provably
continuous.
Do you think that Per Martin-Lf
I was under the impression that, in ghc 6.4 at least, GADTs did just that: use information gained by matching on the
type constructor to refine types. I sort-of expected that the extension to pattern matching would follow.
Or is that a nice paper waiting to be written?
Jacques
Lennart
I would recommend that you look very closely at the design of the
LinearAlgebra package, the Matrix and Vector constructors, and the
underlying implementation data-structure rtable() for Maple's
implementation of all these ideas. About 250 person-days were spent on
just the high-level design,
Henning Thielemann wrote:
On Wed, 29 Jun 2005, Jacques Carette wrote:
9. There are row vectors and column vectors, and these are different
types. You get type errors if you mix them incorrectly.
What do you mean with row vectors and column vectors are different
types? Do you mean
Henning Thielemann wrote:
Mathematical notation has the problem that it doesn't distinguish between
things that are different but in turn discriminates things which are
essentially the same.
I used to think that too. And while that is sometimes true, it is
actually quite rare! When common
[EMAIL PROTECTED] wrote:
One of the things I appreciate and I hate simultaneously in your postings
is that you are so categorical.
'tis indeed simultaneously one of my strengths and one of my weaknesses
;-) I also like to play Devil's Advocate, to draw out the interesting
arguments.
Henning Thielemann wrote:
I'm also aware of that I mean different objects when I write
uniformly '1'. But I know that they are somehow different.
Since '1' can safely be used to denote the unit of any monoid, it does
indeed have a lot of applications. And of course the syntactic artifact
David Roundy and Henning Thielemann have been arguing about the nature
of vectors and matrices, in particular saying:
On Thu, Jun 30, 2005 at 02:20:16PM +0200, Henning Thielemann wrote:
On Thu, 30 Jun 2005, David Roundy wrote:
Matrices _and_ vectors! Because matrices represent
Henning Thielemann wrote:
I'm uncertain about how who want to put the different kinds of
multiplication into one method, even with multi-parameter type classes.
You need instances
(*) :: Matrix - Matrix - Matrix
(*) :: RowVector - Matrix - RowVector
[many other instances removed.]
Henning Thielemann wrote:
Data Orientation = Row | Column
Data Vector a = Vector Orientation [a]
In the first mail you wrote
9. There are row vectors and column vectors, and these are different
types. You get type errors if you mix them incorrectly.
I interpreted that you want to
Bulat Ziganshin wrote:
Language.Haskell.TH.Lib is full of definitions like this:
infixP p1 n p2 = do p1' - p1
p2' - p2
return (InfixP p1' n p2')
btw, such definitions can be simplified by using liftM/ap operations:
instance (Monad m, MyNum v) = MyNum (m
Glynn Clements wrote:
Every other language (including Haskell) tends to have the problem
that eventually you will encounter a situation where the language's
own worldview gets in the way.
Or, to put it another way: if Haskell is so flexible, why do we need
Template Haskell? I can't imagine a
Max Vasin wrote:
Pupeno wrote:
What about this
runDaytimeServer :: DaytimeServer - IO DaytimeServer
runDaytimeServer dts = do
dts' - runStreamDaytimeServer dts
dts' - runDgramDaytimeServer dts'
return dts'
runDaytimeServer dts
= runStreamDaytimeServer dts = runDgramDaytimeServer
I believe you might be able to use (commutative) anti-unification, also
known as generalization for this task.
Jacques
Harry Chesley wrote:
This is more of an algorithm question than a language question, but
any insights would be much appreciated.
The problem is to input a series of programs
Robert Dockins wrote:
The behaviour of NaN actually makes perfect sense when you realise that
it is Not a Number. Things that are not numbers are incomparable with
things that are.
Yes, NaN can be of type Float. But it's not a Float.
If you take that tack, then you have to concede that
Robert Dockins wrote:
On Apr 7, 2006, at 9:43 AM, Jacques Carette wrote:
[Lots of stuff about IEEE 754]
Is this an H' worthy item?
It is worth taking a serious look in conjunction with completely redoing
the Num class. Minor tweaking of the behaviour on NaNs (which requires
a large amount
Andrew U. Frank wrote:
should * always be
commutative or is its use for non-commutative types acceptable?
This very question caused much agony in many design meetings for the CAS
Maple. The list of pros and cons on each side is quite large!
There are too many really nice optimizations
Bulat Ziganshin wrote:
malloc :: Storable a = IO (Ptr a)
malloc = doMalloc undefined
where
doMalloc :: Storable b = b - IO (Ptr b)
doMalloc dummy = mallocBytes (sizeOf dummy)
Is there any reason to not code this as
malloc :: Storable a = IO (Ptr a)
malloc = mallocBytes $
Bertram Felgenhauer wrote:
Jacques Carette wrote:
Bulat Ziganshin wrote:
malloc :: Storable a = IO (Ptr a)
malloc = doMalloc undefined
where
doMalloc :: Storable b = b - IO (Ptr b)
doMalloc dummy = mallocBytes (sizeOf dummy)
Is there any reason to not code
Since we're off-topic...
Any sequence of numbers given by a linear recurrence equation with
constant coefficients can be computed quickly using asymptotically
efficient matrix operations. In fact, the code to do this can be
derived automatically from the recurrence itself.
Here is what you
Daniel Fischer wrote:
On Aug 16, 2010, at 6:03 PM, Jacques Carette wrote:
Any sequence of numbers given by a linear recurrence equation with
constant coefficients can be computed quickly using asymptotically
efficient matrix operations. In fact, the code to do this can be
derived
On 23/10/2010 5:19 PM, Daniel Peebles wrote:
Just out of curiosity, why do you (and many others I've seen with
similar proposals) talk about additive monoids? are they somehow
fundamentally different from multiplicative monoids?
People usually use additive notation for commutative monoids,
On 02/11/2010 8:16 PM, Conal Elliott wrote:
Vector (Complex a) is a vector with respect to both 'a' and 'Complex a'.
Even worse, () is a vector w.r.t. *every* scalar type.
Why is this bad? () is the canonical 0-dimensional vector space.
0-dimensional vector spaces are very useful because
On 21/11/2010 8:33 PM, wren ng thornton wrote:
On 11/20/10 6:33 AM, Ketil Malde wrote:
I guess this makes [X] an exponential type, although I don't remember
seeing that term :-)
Nope. (a-b) is the exponential type, namely |a-b| = |b|^|a|.
[_] is just a solution to the recursive equation [x]
Is anyone working on a Language.C++ module, similar to the wonderful
Language.C ? Right now just the syntax and a pretty-printer would be
really nice to have...
Jacques
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Haskell-Cafe@haskell.org
I was trying to create a typeclass for an abstract Stack class, and ran
into some problems. The following 'works' fine:
{-# OPTIONS_GHC -XEmptyDataDecls -XFlexibleContexts
-fno-monomorphism-restriction #-}
module Stack where
data Void
class Stack s where
push_ :: s a r - b - s b (s a r)
Andrew Wagner wrote:
Wadler posted a blog entry the other day about a paper on
pattern-matching in Haskell (http://wadler.blogspot.com/). I've taken
a first stab at turning it into actual code for hackage
(http://hpaste.org/13215). There are two commented-out definitions
that don't
Deadline
June 29-30, 2007: Workshop
Program Committee
Lennart Augustsson http://www.cs.chalmers.se/%7Eaugustss [Credit Suisse]
Wieb Bosma http://www.math.ru.nl/%7Ebosma/[Radboud University
Nijmegen, Netherlands]
Jacques Carette http://www.cas.mcmaster.ca/%7Ecarette (co-Chair)
[McMaster
Alfonso Acosta wrote:
Just in case it helps, I ported the code of Norvigs Paradigms of
Artificial Intelligence Programming chapter 8 (integrals and
derivates) for a collage course.
A link to this code would have been / would still be most appreciated.
Jacques
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