On 1/8/11 5:23 AM, C K Kashyap wrote:
Hi,
Thanks to Luke Palmer's explanation. I got a better idea of functors.
I just want to ratify my understanding of what a functor is -
according to category theory, functors are arrows between categories
... these arrows map objets and arrows from one
On 12/23/10 11:46 PM, Mario Blažević wrote:
On Thu, Dec 23, 2010 at 11:25 PM, Tony Morristonymor...@gmail.com wrote:
...regardless of the utility of a contravariant functor type-class, I
strongly advocate for calling it Contrafunctor and not Cofunctor. I
have seen numerous examples of
On 12/24/10 12:26 AM, C. McCann wrote:
As far as I understand (which may not actually be all that far),
contravariant functors just go to or from an opposite category, a
distinction that is purely a matter of definition, not anything
intrinsic.
Yes.
On the other hand, Applicative and Monad
On 12/23/10 9:41 PM, Daniel Peebles wrote:
For me, mostly naming. Cofunctor isn't the right name for it, and comap,
while short, feels wrong. Contrafunctor feels better but is also cumbersome.
No problems with Comonad, though.
It is wrong. Cofunctors are exactly functors. It's unfortunate that
On 12/13/10 8:25 AM, Paul Sargent wrote:
How about, as a cheep and cheerful method to get up running. If the premise
is that the original server is trustworthy and the mirrors aren't, then:
1) Hash all packages on the original server.
2) Hash goes into a side car file (e.g.packagename.sha) that
On 12/9/10 4:04 PM, Richard O'Keefe wrote:
On 10/12/2010, at 12:18 AM, Markus Läll wrote:
My take on the issue is that we should make it possible to easily mirror
hackage (what the OP asked for), so that people could use it when they wanted
to, and have a list of the mirrors on the wiki.
On 12/11/10 5:59 AM, wren ng thornton wrote:
On 12/9/10 4:04 PM, Richard O'Keefe wrote:
As long as the material from Y replicated at X is *supposed* to be
publicly available, I don't see a security problem here. Only Y accepts
updates from outside, and it continues to do whatever authentication
On 12/6/10 2:35 AM, Vincent Hanquez wrote:
I would really like mirrors too.
But before that happens it would be nice to have signed packages on
Hackage, preventing
a mirror to distribute compromised stuff (intentionally or
unintentionally).
+1.
This should be done during sdist, before
On 12/6/10 7:26 PM, Daryoush Mehrtash wrote:
I am having hard time understanding the following code. The code is from
Applicative Parser library:
http://hackage.haskell.org/packages/archive/uu-parsinglib/2.5.5.2/doc/html/src/Text-ParserCombinators-UU-BasicInstances.html
instance (Show a,
On 12/4/10 10:34 PM, wren ng thornton wrote:
FWIW, I've been on the board of directors for a 501(c)(3), helped write
their bylaws, and know a few people in the business (lawyers, etc). I'm
willing to offer advice, effort, and references whenever the committee
decides to do this.
I tried cc-ing
On 12/5/10 11:23 AM, Ketil Malde wrote:
Florian Lengyelflorian.leng...@gmail.com writes:
Why is there even any consideration of some committee if someone wants to
mirror the Hackage site? Why not mirror the site?
+1
Alright, Mr. Wiseguy, she said, if you're so clever, you tell us
On 12/4/10 11:31 AM, Dan Knapp wrote:
With Hackage down, now seemed like a good time to push this issue
again. It's such an important site to us that it's really rather a
shame there are no mirrors of it. I have a personal-and-business
server in a data center in Newark, with a fair chunk of
On 12/4/10 2:21 PM, Riad S. Wahby wrote:
Ozgur Akgunozgurak...@gmail.com wrote:
This is a very generous offer. However, I must say I like the following idea
more:
http://www.reddit.com/r/haskell/comments/efw38/
reminder_hackagehaskellorg_outage_tomorrow_due_to/c17u7nk
That sounds like a
On 12/2/10 4:47 PM, Iavor Diatchki wrote:
Hi,
You have it exactly right, and I don't think that there's a
particularly deep reason to prefer the one over the other. It seems
that computer science people
tend to go with the (product-function) terminology, while math people
seem to prefer the
On 11/30/10 11:05 AM, Simon Marlow wrote:
On 30/11/10 05:49, wren ng thornton wrote:
I'll see if I can make a workaround with that, but as I said: Simon's
already confirmed that this is a bug, I'm just looking for a ticket
number or a version where it's fixed.
And fix it I did:
Wed Jan 27 11
On 11/29/10 6:36 PM, Bryan O'Sullivan wrote:
On Sat, Nov 27, 2010 at 9:05 PM, wren ng thorntonw...@freegeek.org wrote:
So I've just started playing around with STM and -threaded programs and
I've run into a bug. The bug is similar to [1] except that the file in
question is a Posix FIFO
On 11/28/10 9:59 AM, Jafet wrote:
But GHC does not accept type synonym instances unless they are fully applied.
That's precisely the problem, and why a newtype is used. More than GHC
implementation details, there's the deeper problem that allowing general
type-level functions causes
So I've just started playing around with STM and -threaded programs and
I've run into a bug. The bug is similar to [1] except that the file in
question is a Posix FIFO instead of a Bluetooth device. Same behavior:
always errors with -threaded, but expected behavior when not -threaded
(i.e.,
On 11/20/10 6:33 AM, Ketil Malde wrote:
Andrew Coppinandrewcop...@btinternet.com writes:
Now here's an interesting thought. Haskell has algebraic data
types. Algebraic because they are sum types of product types (or,
equivilently, product types of sum types). Now I don't actually know
what
On 11/20/10 9:55 AM, Marcelo Sousa wrote:
Hi,
I'm having currently a problem with System.Directory in my mac os.
System Version: Mac OS X 10.6.5
Kernel Version: Darwin 10.5.0
Prelude System.Directory let dirTest = do {dir- getCurrentDirectory;
doesDirectoryExist dir}
Prelude
On 11/19/10 4:05 PM, Andrew Coppin wrote:
So what would happen if some crazy person decided to make the kind
system more like the type system? Or make the type system more like the
value system? Do we end up with another layer to our cake? Is it
possible to generalise it to an infinite number of
On 11/19/10 10:05 PM, Ryan Ingram wrote:
On Fri, Nov 19, 2010 at 1:05 PM, Andrew Coppin wrote:
So is Either what is meant by a sum type?
Similarly, (X, Y) [...] is this a product type?
Yes and no. Unfortunately there's some discrepancy in the terminology
depending on who you ask. In the
On 11/19/10 10:05 PM, Ryan Ingram wrote:
Not exactly; in the phantom type case, the two sets ARE disjoint in a
way; there are no objects that are both Foo Int and Foo Bool (although
there may be objects of type forall a. Foo a -- more on that later).
Whereas the type keyword really creates two
On 11/13/10 8:15 AM, Will Sonnex wrote:
Infinite values (lazy-evaluation in general) also give Zeno a problem,
since you can no longer use structure as a well-defined ordering for
induction. A property such as reverse (reverse xs) === xs does not
work for infinite lists, since you can
On 11/12/10 5:33 AM, Richard Senington wrote:
It does not give the results you would want. This may have something to
do with picking good parameters for the mkLehmerTree function.
For example, using a random setup, I just got these results
result expected range
16.814 expected = 16.0 (1,31)
On 11/12/10 4:53 PM, Ryan Ingram wrote:
From http://www.haskell.org/ghc/docs/6.12.2/html/users_guide/bugs.html#bugs-ghc:
GHC's inliner can be persuaded into non-termination using the standard
way to encode recursion via a data type:
More specifically, since your bad2 does not look recursive,
On 11/12/10 6:56 PM, Michael Litchard wrote:
I've been working on a project that requires me to do screen scraping.
When I first started this, I worked off of other people's examples.
Not one used regex. By luck I found someone at work to help me along
this project. His clues and hints don't use
On 11/11/10 8:54 PM, Richard O'Keefe wrote:
I remind readers once again that in SML record selectors *don't* clash with
names of functions. I am not concerned here to argue either for or against
SML-style records and their selectors, only to point out that wanting
*record fields* whose
On 11/10/10 4:59 PM, Dan Doel wrote:
I'll admit, the Agda overloading is handy. But I've always considered
Haskell's lack of ad-hoc overloading to be a feature. Type classes give
sensible types for what would normally be ad-hoc. Adding back ad-hoc functions
that have no available general type
On 11/10/10 9:18 AM, Max Bolingbroke wrote:
On 10 November 2010 12:49, Patrick LeBoutillier wrote:
I'm a total newbie with respect to the lambda calculus. I tried
(naively) to port these examples to Haskell to play a bit with them:
You can give type signatures to your first definitions like
On 11/7/10 11:54 AM, Henning Thielemann wrote:
Awful - I would not like to complicate my Cabal files this way. This is
like copying the Build-Depends enumeration to all depending packages.
Oh, I agree :)
I wonder if you can include ghc in the build-tools: field and whether
cabal-install
On 11/5/10 7:54 AM, Alexey Khudyakov wrote:
We already know that there are noncommutative modules/vectorspaces of
interest (e.g., modules over quaternions and modules over graph paths),
why not support them from the beginning? It seems like you're going out
of your way to exclude things that
On 11/6/10 2:09 AM, Sebastian Fischer wrote:
Hello,
I'm curious and go a bit off topic triggered by your statement:
On Nov 6, 2010, at 12:49 PM, rocon...@theorem.ca wrote:
An applicative functor morphism is a polymorphic function,
eta : forall a. A1 a - A2 a between two applicative functors
On 11/6/10 3:13 AM, Ivan Lazar Miljenovic wrote:
On 6 November 2010 17:52, Reiner Popereiner.p...@gmail.com wrote:
Ah, I hadn't thought of that. But doesn't the version of GHC change
much more often than the version of base does?
Each major version of GHC has a different (major) version of
On 11/6/10 6:20 AM, Reiner Pope wrote:
I was aware of this condition, but I'm not precisely sure it addresses
my requirements. When you run cabal install some-package, cabal
reads all version constraints listed in the build-depends field, and
chooses which versions of which packages to download
On 11/4/10 6:32 PM, Gregory Crosswhite wrote:
On 11/04/2010 03:06 PM, Dan Doel wrote:
Implementing type inference can be very easy in a logic language,
because most
of the work in a non-logic language is implementing unification:
[...]
Cool! Thank you very much; that is exactly the kind of
On 11/3/10 12:34 AM, Gregory Crosswhite wrote:
On 11/2/10 8:37 PM, wren ng thornton wrote:
Though I would suggest you look at the LogicT library instead of using
actual lists... Also, you may be interested in reading the LogicT
paper[2] or this paper[3] about search combinators in Haskell. Both
On 11/1/10 6:28 PM, Andrew Coppin wrote:
The other day, I accidentally came up with this:
|{-# LANGUAGE RankNTypes #-}
type Either x y= forall r. (x - r) - (y - r) - r
left :: x - Either x y
left x f g= f x
right :: y - Either x y
right y f g= g y
|
This is one example; it seems that just
On 11/2/10 7:09 AM, Sebastian Fischer wrote:
On Nov 2, 2010, at 9:27 AM, Gregory Crosswhite wrote:
Which does raise the question: when is it better to use a logic
programming language instead of the list monad?
It is more cumbersome to model logic variables and unification in a pure
On 10/31/10 6:36 PM, Alexey Khudyakov wrote:
On Wed, Oct 27, 2010 at 2:53 AM, wren ng thornton wrote:
Is there any good reason for forcing them together? Why not, use the
hierarchy I proposed earlier?
[...]
Main reason is that it complicate creation of instances for types for which
On 10/31/10 7:10 PM, Derek Elkins wrote:
Well, you can get A Novel Representation of Lists and Its Application
to the Function 'Reverse' by John Hughes online published in 1986
which is referenced by Wadler's 1987 The Concatenate Vanishes and
references Richard Bird's 1984 paper Transformational
On 10/31/10 10:26 PM, Richard O'Keefe wrote:
On 1/11/2010, at 2:02 PM, wren ng thornton wrote:
(Though I find it curious that you think the logic version is so different...)
The logic programming version
uses a SINGLE data structure for lists and differences, so that
+ converting from
On 10/29/10 2:33 AM, Gregory Crosswhite wrote:
Also, this is a complete aside but what the heck. :-)
Has anyone else been driven crazy by the way that Java code and
libraries are documented? It seems like whenever I try to figure out how
to use a piece of Java code, the functionality is spread
On 10/29/10 11:18 AM, Daniel Peebles wrote:
Speaking of MagicHash, is it really necessary to take an operator with
potential like (#) just to keep primitive symbols separate from the rest?
At least from my 2010 Haskell learner perspective, it seems odd to create a
whole language
On 10/29/10 8:33 PM, C. McCann wrote:
On Fri, Oct 29, 2010 at 7:54 PM, wren ng thorntonw...@freegeek.org wrote:
I'm sort of torn on this issue. On the one hand (#) has great potential as
an operator, on the other hand I've found that having something like
-XMagicHash (or TeX's \makeatletter
On 10/28/10 10:42 AM, Ben Millwood wrote:
Here's the wiki page:
http://hackage.haskell.org/trac/haskell-prime/wiki/CompositionAsDot
Personally I think function composition is what Haskell is all about
and it is absolutely essential that the syntax for it be lightweight.
If we think using . as
On 10/26/10 8:51 AM, Alexey Khudyakov wrote:
On 24.10.2010 03:38, wren ng thornton wrote:
I don't care much about the name of the class, I'd just like support for
monoids, semirings,... when they lack a group, ring,... structure.
Then what about following type class hierarchy? I think
On 10/24/10 7:09 AM, Maciej Piechotka wrote:
Iteratee-compress provides compressing and decompressing enumerators
including flushing. Currently only gzip is provided but at least bzip
is planned.
Changes from previous version:
- Independent from zlib library (Haskell one, not C)
- Allow
On 10/24/10 8:14 PM, Felipe Lessa wrote:
On Sun, Oct 24, 2010 at 9:59 PM, Maciej Piechotkauzytkown...@gmail.com wrote:
Currently I thought only about bzip2/gzip. Probably .xz support would
follow if any.
LZO, as you said, is on GPL-2. While I have no problems with GPL-2 some
potential users
On 10/23/10 2:33 PM, Brandon S Allbery KF8NH wrote:
I think they mean please don't conflate `reentrant' with `blocking' in the
FFI.
Not knowing much about the guts of GHC's implementation of the FFI, I
wonder if there would actually be an implementational difference in
distinguishing
On 10/23/10 4:53 PM, Alexey Khudyakov wrote:
On 23.10.2010 05:11, wren ng thornton wrote:
I'd rather see,
class Additive v where -- or AdditiveMonoid, if preferred
zeroV :: v
(^+^) :: v - v - v
class Additive v = AdditiveGroup v where
negateV :: v - v
Seems good for me. One more instance
On 10/23/10 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? Or is it just a matter of notation?
When I was playing with building
On 10/23/10 7:52 PM, wren ng thornton wrote:
I'd argue that neither usage is primary, and therefore the best
solution is actually to have three classes (neutral, additive, and
multiplicative) with two functors (additive-neutral,
multiplicative-neutral) to connect them[1].[...]
[1] the Exp/Log
On 10/21/10 5:38 AM, Ketil Malde wrote:
I'm always getting two copies of everything in haskell@, since
everything is cross-posted to -cafe. Are there actually people
subscribed to -cafe, but *not* to hask...@? And if so, why?
I am. In part because I don't want to get two copies of
On 10/21/10 2:32 PM, Christopher Done wrote:
[1] http://imgur.com/lnkE7.png
[2] http://previasports.com/haskellers_website/
I like the colour theme of the former and the layout of the latter.
The colour theme of the first is more professional, I think. I vote
that styles should be consistent.
On 10/22/10 8:46 AM, Alexey Khudyakov wrote:
Hello everyone!
It's well known that Num Co type classes are not adequate for vectors
(I don't mean arrays). I have an idea how to address this problem.
Conal Elliott wrote very nice set of type classes for vectors.
(Definition below). I used them
On 10/20/10 9:12 AM, Anthony Cowley wrote:
We don't want people
outside of an area of interest governing name choices that lessen the
value of the tags.
To be honest, when the thread first came up, I was afraid NLP (or AG)
would end up on the cutting block because of that...
As a strawman
On 10/20/10 7:09 AM, Simon Peyton-Jones wrote:
Yes, you can freely use Foo/unFoo. There's no runtime penalty. (In the jargon
of GHC's intermediate language, Foo and unFoo translate to *type-safe casts*,
which generate no executable code.
When does the conversion to type-safe casts occur
On 10/19/10 5:47 AM, Ryan Newton wrote:
That sounds good to me. In any case the parallel map/fold operations by
themselves shouldn't compromise the abstraction.
Perhaps an eventual solution would be to start including parallel maps/folds
right inside the standard libraries. I haven't began
On 10/19/10 9:32 AM, Michael Snoyman wrote:
There are 11 skills I'm leaning towards dropping, all because they
fall in the too vague/too general category. Your input is requested on
these. They are:
Attribute Grammar
Categorical Programming
Denotational design
Proving observational equivalence
On 10/19/10 2:12 PM, Christopher Done wrote:
Questions (I'm talking about GHC when I refer to compilation):
(1) Are fromString and fromIntegral ran at compile time? I don't think
that this is the case. I think they are just translated to fromString
Hello, World! and fromIntegral 2 verbatim.
(2)
On 10/16/10 10:48 AM, Ben Franksen wrote:
Don Stewart wrote:
It is open source, and was born open source. It is the product of
research.
How can a language be open source, or rather, how can it *not* be open
source? The point of a (programming) language is that it has a published
('open')
On 10/16/10 11:34 AM, Ben Franksen wrote:
Christopher Done wrote:
To solve this ambiguity that phrase is a link that people can click to
find out what it means. Object oriented, dynamically typed,
stack-based are about as meaningful.
The difference may be that everyone thinks he knows what
On 10/16/10 11:22 AM, Ben Franksen wrote:
Much better. Though I *do* think mentioning the main implementations and
their qualities is a good thing to o, right after this:
[...]The most
important Haskell implementation, ghc [like to ghc page], has served as a
test bed for practical application
On 10/16/10 3:39 PM, Stephen Tetley wrote:
Hello list
The Monad and Applicative instances for functions are equivalent to
the respective Reader vesions (I use equivalent along the lines of -
operationally the same but without the type distinction / newtype).
There is also the Monoid instance
On 10/16/10 8:25 PM, Dan Doel wrote:
On Saturday 16 October 2010 7:04:23 pm Ben Millwood wrote:
On Fri, Oct 15, 2010 at 9:28 PM, Andrew Coppin wrote:
I'm still quite
surprised that there's no tool anywhere which will trivially print out
the reduction sequence for executing an expression.
On 10/9/10 2:02 AM, Alex Rozenshteyn wrote:
This came up as I was doing homework for natural language processing.
I'm constructing a trigram model from training data, but I also need the
bigram and unigram counts. I could, for each triple of characters, add the
3 tuple to a trigram map and
On 10/10/10 7:00 PM, Johannes Waldmann wrote:
My point was: you need to find/define two operators, not just one.
Sure, I need flip ($) and flip (.)
Since the Prelude forgot to define these (and flip map),
the question was: are there established names for these two operators?
I don't
On 10/7/10 8:35 AM, Ketil Malde wrote:
Christian Sternagelc.sterna...@gmail.com writes:
recently I was wondering about the two words order and ordering
I would use ordering to mean the relation or function that orders
(ranks) elements, and I'd use order to refer the actual progression.
So by
On 10/8/10 5:46 PM, Thomas DuBuisson wrote:
Alex,
The containers library can do this already - there are no constraints
on the elements of a Map. For example:
type TripleNestedMap a = Map Int (Map Char (Map String a))
But this is rather silly as you can just do:
type MapOfTriples a = Map
On 10/3/10 5:52 PM, Victor Nazarov wrote:
I suggest to pay more attention to haskell's standard library.
allButLast is called init in Data.List module.
Second, do not use explicit recursion. You can capture recursion using
some high-order function like map, filter, foldr and so on:
On 10/2/10 3:13 PM, Christopher Done wrote:
There's nothing more annoying than having to introduce intermediate
bindings when you're going to immediate pattern match against it
immediately and never use it again. It's both annoying to have to
think of a variable name that makes sense and is not
On 9/24/10 5:35 AM, Axel Benz wrote:
Can anybody explain why this happens and how I can compose f and g?
Hint: It works fine if f is defined as an unary function.
As already mentioned: (g . f) x y = (\z- g (f z)) x y = g (f x) y
In order to get it to work you need to say that you want to
was what I was pointing out in in the post described as:
On Wed, Sep 22, 2010 at 11:10 AM, David Sankelcam...@gmail.com wrote:
wren ng thornton provided an evaluation using another operational semantics
(reference?). Under this semantics, this optimization would be called
partial evaluation
On 9/24/10 10:01 PM, Gregory Crosswhite wrote:
Hey everyone,
There is something that has been bugging me recently about the
Applicative class and the Monad class.
Any type constructor F that is a Monad has a natural Applicative instance,
($) :: F (a - b) - F a - F b
mf $ ma = do
f - mf
a - ma
On 9/22/10 11:48 AM, Daniel Fischer wrote:
On Wednesday 22 September 2010 17:10:06, David Sankel wrote:
The following code (full code available here[1], example taken from
comments here[2]),
const' = \a _ - a
test1 c = let a = const' (nthPrime 10)
in (a c, a c)
test2 c = let
On 9/18/10 8:00 AM, Sjoerd Visscher wrote:
On Sep 17, 2010, at 10:39 PM, Ben Franksen wrote:
What I actually wanted was a mathematical definition, though.
Here's a definition of pointed objects:
http://ncatlab.org/nlab/show/pointed+object
pointed objects, pointed sets/groups/topospaces,
On 9/16/10 4:59 PM, Ben Franksen wrote:
wren ng thornton wrote:
The difference is that, for let-bindings, once you've figured out a type
of the variable being bound, then that type can be generalized. [...]
Whereas, lambda-bindings don't get generalized, and so they'll always be
monomorphic
On 9/17/10 4:39 PM, Ben Franksen wrote:
Thanks for the link. What I actually wanted was a mathematical definition,
though. From the TMR article I gather that a pointed functor could be
defined as an endo-functor
F: C - C
together with a natural transformation
pure: Id - F
where Id: C
On 9/17/10 12:48 PM, ender wrote:
my question is, why not define the function father and mother as type of
father::Maybe Sheep - Maybe Sheep? this can also
clean the code and it avoid the additional function comb
Do note that `comb` is giving you a natural way of creating those functions:
On 9/17/10 4:04 PM, Ben Franksen wrote:
wren ng thornton wrote:
Note that when compilers do CPS conversion, everything is
converted into let-binding and continuations (i.e., longjump/goto with
value passing). It's just dual to the everything-is-lambda world,
nothing special.
Do you know
On 9/15/10 9:11 AM, Kevin Jardine wrote:
Hi Malcolm,
In this case, I am counting on GHC's
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
feature to derive the instances for the classes I am including in the
deriving clause.
So perhaps portability is not a big issue here in any case.
Yes, but
On 9/15/10 10:39 PM, Conal Elliott wrote:
Hi Alex,
In Haskell, data structures cache, while functions do not.
Exactly. What this means is that when you call (slowFib 50) Haskell does
not alter slowFib in any way to track that it maps 50 to $whatever;
however, it does track that that
On 9/13/10 6:22 AM, Michael Lazarev wrote:
Thanks for examples and pointers.
Since I came from Lisp, it never occurred to me that let and lambda
are different constructs in Haskell.
I thought that
let x = y in f
is really
(\x - f) y
It turns out that let is about declarations which
On 9/13/10 6:23 PM, Paolo G. Giarrusso wrote:
Then, I would also like to understand what exactly a strict functor
is, in detail, and/or a link to the post you reference.
I'm assuming the OP was referring to a functor for strictness I
mentioned recently in the discussion about pointed
On 9/11/10 3:43 PM, Daniel Fischer wrote:
- is there a specification of which are the core packages?
core as in *do not update*?
Basically, what comes with GHC shouldn't be updated.
Though I heard updating Cabal was okay.
I tried updating Cabal once (recently) and it broke things in the same
On 9/10/10 12:47 AM, David Menendez wrote:
It seems like you could use a similar argument to show that fmap id /= id.
Specifically, xs and map id xs are equivalent lists, but they occupy
different locations in memory. By replacing xs with map id xs, you can
come arbitrarily close to doubling a
On 9/9/10 1:04 AM, David Menendez wrote:
Fascinating. I figured there might be a counter-example involving seq,
but this is pretty subtle.
In particular, would it be fair to say that in Haskell-without-seq, E
(f a) a and E (f a) (f a) are indistinguishable?
Yes, I think that without
On 9/7/10 12:33 AM, Ivan Lazar Miljenovic wrote:
On 7 September 2010 14:24, wren ng thorntonw...@freegeek.org wrote:
On 9/7/10 12:04 AM, Ivan Lazar Miljenovic wrote:
Not quite sure what you mean by a mis-match
Just that they're not the same thing. For example, ZipList supports pure but
it
On 9/7/10 7:26 AM, Neil Brown wrote:
On 07/09/10 05:24, wren ng thornton wrote:
Just that they're not the same thing. For example, ZipList supports
pure but it has no meaningful instance of singleton since every
ZipList is infinite.
I don't believe that every ZipList is infinite
On 9/7/10 4:21 AM, Daniel Fischer wrote:
On Tuesday 07 September 2010 05:22:55, David Menendez wrote:
In fact, I think *every* appropriately-typed function satisfies that
law. Does anyone know of a counter-example?
-- | Multiply the *Hask* category by its number of objects.
data E a
On 9/7/10 3:10 PM, Ben Millwood wrote:
So I wonder what people
think of the use of CPP in Haskell code, what alternatives people can
propose, or what people hope to see in future to make conditional
compilation of Haskell code more elegant and simple?
The only thing I ever use CPP for in
On 9/5/10 10:19 AM, Ivan Lazar Miljenovic wrote:
Hmmm is there any reason for Functor to be a superclass of
Pointed? I understand Functor and Pointed being superclasses of
Applicative (which in turn is a superclass of Monad), but can't see
any relation between Pointed and Functor...
On 9/6/10 2:35 AM, Ivan Lazar Miljenovic wrote:
Well, if we consider what this does, pure is equivalent to singleton
for container types. The actual definition of pure (or any other
aspect of Pointed) doesn't require Functor; however there are
properties for types that are instances of Functor
On 9/6/10 1:33 PM, David Menendez wrote:
For that matter, can you even describe what pure is intended to do
without reference to* or join?
As already stated: fmap f . pure = pure . f
--
Live well,
~wren
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On 9/6/10 11:50 AM, Gábor Lehel wrote:
On Mon, Sep 6, 2010 at 5:11 PM, John Latojwl...@gmail.com wrote:
But please don't make Pointed depend on Functor - we've already
seen that it won't work for Bloom filters.
I think most people have been using Pointed merely as shorthand for
Pointed
On 9/6/10 12:53 PM, John Lato wrote:
I'd like to make one more argument in favor of my preference for more
splitting of type classes.
FWIW, I agree that more splitting is generally good. This is one of the
problems I have with the various proposals for a ListLike class. They
conflate the
On 9/6/10 11:46 PM, Ivan Lazar Miljenovic wrote:
Well, my current work is to implement restricted versions of the
various type classes (I'm undecided if they should be split off into a
separate package or not) and then have the Data.Containers module
basically define type aliases (which will
On 9/7/10 12:04 AM, Ivan Lazar Miljenovic wrote:
Perhaps this just means that union/insert should be part of some other
class.
That is part of the plan (I'm tentatively calling the class with the
insert method Buildable or Extendable); this means that if a
type is an instance of Monoid (for
On 9/3/10 12:16 AM, Ivan Lazar Miljenovic wrote:
1) How should I name the kind * versions? For example, the kind *
version of Functor is currently called Mappable with a class method of
rigidMap. What should I call the kind * version of Foldable and its
corresponding methods? Is there a valid
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