On Sun, Sep 29, 2013 at 9:13 PM, Ryan Newton rrnew...@gmail.com wrote:
Thanks, that's interesting to know (re: Fortress).
Interestingly, in my Fortress days we looked at both using a split-like
interface and at a more foldMap / reduce - like interface, and it seemed
like the latter worked
if you've come up with an application that requires
split itself, and that *isn't* zip. I recall we decided zip was better
done with element-and-index iteration over one of the structures and
indexing into the other since most tree structures don't actually zip
properly anyway.
-Jan-Willem
This has all the marks of a 64-bit-only code running on a 32 bit machine.
It looks like you're getting the high bits of the rng with a signed shift
right, ultimately yielding only the sign bit.
I suspect mwc-random needs to use Int64 rather than Int internally in a few
critical places.
On Wed,
On Mon, Nov 5, 2012 at 5:52 PM, Johan Tibell johan.tib...@gmail.com wrote:
The tricky part is to define the semantics of this pragma in terms of
Haskell, instead of in terms of Core. While we also need the latter, we
cannot describe the feature to users in terms of Core. The hard part is to
be tricky to bound the required
sizes of inputs even if you know how much of the output you want (imagine a
call to takeWhile or filter on an infinite list).
-Jan-Willem Maessen
Regards,
Malcolm
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-do rather too much computation (all of it,
in particularly poor cases) compared to systems specifically tailored
to self-adjustment.
-Jan-Willem Maessen
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uu' = uu `addEquation` e
This kind of thing happens all over the place in Haskell code -- it's
a very natural coding style -- but if you want to preserve purity it's
tough to compile without laziness.
-Jan-Willem Maessen
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On Thu, Mar 24, 2011 at 11:36 AM, Simon Peyton-Jones
simo...@microsoft.com wrote:
| class Monoid (GeneratorOf a) = Generable a where
| type GeneratorOf a :: * - *
| construct :: GeneratorOf a - a
|
| Now, it seems I need FlexibleInstances to do this when I'm using an
| associated type
whenever I use associated types in my programs?
-Jan-Willem Maessen
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On Wed, Feb 23, 2011 at 11:08 AM, Johan Tibell johan.tib...@gmail.com wrote:
...
HashTable is not a concurrent data structure. You need e.g. a lock
free mutable hash table.
Good implementations of which are *not* thick on the ground. Even
java.util.concurrent isn't fully lock-free.
-Jan
caching sizes at nodes, one of which is to count overlap during union
or intersection operations (since this involves counting leaves that
are visited during these operations).
-Jan-Willem Maessen
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and write primitives were prtty commonly
used in Id programs. The take/put view can also usefully be thought
of as a 1-element blocking channel.
-Jan-Willem MAessen
Thanks,
Neil.
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and
Haskell-style classes rather than OO + generic typing. The Fortress
type system actually approximates pattern matching in some interesting
ways, but it's not the same.
-Jan-Willem Maessen
Experienced Fortress programmer (!)
- Jake
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to unexpected space leaks (if you
didn't intend to keep the list of fibs around forever).
-Jan-Willem Maessen
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optimization. Unoptimized call-by-need
indeed evaluates (nthPrime 10) twice in test2, but only once in
test1. (Challenge: prove observationl equivalence of these two
fragments under call-by-need.)
-Jan-Willem Maessen
On Fri, Sep 24, 2010 at 5:58 PM, David Sankel cam...@gmail.com wrote:
On Wed
they are fused using
the RULES.* There's not really any benefit to inlining them
otherwise, and it duplicates code.
-Jan-Willem Maessen
--
Live well,
~wren
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of settings.
It also offers really elegant implementations of union and unions.
Whether that means they're quickish I leave to the benchmarkers.
-Jan-Willem Maessen
--
Live well,
~wren
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that's rather unimportant compared to
allocation time / memory footprint issues here.
-Jan-Willem Maessen
I implemented a ErrCPS monad which does exactly that, but the speed has
been disappointing. It runs almost exactly 3x slower than a drop in
replacement using the MonadError instance
On Sat, Mar 27, 2010 at 8:16 PM, Roman Leshchinskiy r...@cse.unsw.edu.auwrote:
On 28/03/2010, at 01:36, Jan-Willem Maessen wrote:
It's worth pointing out that there's a bit of bang-pattern mysticism
going on in this conversation (which has not been uncommon of late!). A
non-buggy
-Jan-Willem Maessen
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the order of forcing of strict variables.
Putting in bang patterns is a good idea to plug the obvious space leak when
run without optimization, but isn't going to make a difference for
optimizing compilation of obviously-strict functions.
-Jan-Willem Maessen
a = ...[internals go here]...
Would this be enough to cue us that Set has a more interesting kind than just *
- * ?
-Jan-Willem Maessen
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On Mar 9, 2010, at 5:53 AM, Max Cantor wrote:
Isn't this just an extension of the notion that multi-parameter typeclasses
without functional dependencies or type families are dangerous and allow for
type-naughtiness?
I wondered the same thing, but came up with an analogous problematic
of the
lightweight calls that Linux has added for the purpose). Obviously this has a
cost if anyone falls out of the spin loop---and it's pretty likely some thread
will have to wait a while.
-Jan-Willem Maessen
Cheers,
Simon
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On Mar 4, 2010, at 9:05 PM, Roman Leshchinskiy wrote:
On 05/03/2010, at 04:34, stefan kersten wrote:
i've been hunting down some performance problems in DSP code using vector and
the single most important transformation seems to be throwing in INLINE
pragmas
for any function that uses
with a
common interface (something like this one)?
class Generator t e | t - e
mapReduce :: (Monoid m) = t - (e - m) - m
-Jan-Willem Maessen
Another Fortress/Haskell crossover
Greetings,
Johann
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as
one-liners. It's got a messy, ugly type signature, but it does everything you
want as efficiently as you want.*
-Jan-Willem Maessen
* Actually, this is only true if you add the key as an argument to the third
function, so that you can also encode unionWithKey etc! I've skipped that here
On Jan 27, 2010, at 9:42 AM, Hans Aberg wrote:
On 27 Jan 2010, at 14:56, Jan-Willem Maessen wrote:
So here, one would want:
(a - c) - (b - c) - (a - b - c) - Map k a - Map k b - Map k c
where the two first functions are applied when the first or second key is
missing.
Ah, the swiss
On Jan 27, 2010, at 10:54 AM, Hans Aberg wrote:
On 27 Jan 2010, at 16:33, Jan-Willem Maessen wrote:
I'm not sure why you want to throw in functions between maps in the two
first arguments. Then there is no requirement that single keys are
preserved.
But it is a good idea to have
-Willem Maessen
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On May 13, 2009, at 6:58 PM, wren ng thornton wrote:
Jan-Willem Maessen wrote:
I wanted to clear up one misconception here...
wren ng thornton wrote:
In heavily GCed languages like Haskell allocation and collection
is cheap, so we don't mind too much; but in Java and the like,
both
On May 14, 2009, at 10:17 AM, Duncan Coutts wrote:
On Thu, 2009-05-14 at 09:03 -0400, Jan-Willem Maessen wrote:
Hmm, I think neither of the data structures you name actually support
both O(lg n) indexing and O(lg n) cons or append. That said, your
point is well taken, so let's instead state
On May 14, 2009, at 11:01 AM, Dan Doel wrote:
On Thursday 14 May 2009 9:03:30 am Jan-Willem Maessen wrote:
Hmm, I think neither of the data structures you name actually support
both O(lg n) indexing and O(lg n) cons or append. That said, your
point is well taken, so let's instead state
programs would become
readable? And as a special bonus, though it may offend your
sensibilities, numeric prelude programs might be able to use
unqualified import in certain circumstances?
-Jan-Willem Maessen
[For each language, its own idiom
in progress, but there's a description and
pointer to talk slides here:
http://www.eecs.berkeley.edu/~lmeyerov/#projects
Presumably their forthcoming HotPar paper will yield more details.
-Jan-Willem Maessen
On Feb 3, 2009, at 2:39 PM, Conal Elliott wrote:
[Spin-off from the haskell-cafe
, and humans get wrong. Surely it
wouldn't be that hard for GHC to transform self recursion in this way
(possibly subject to the condition that the result be worth inlining)?
[phc did this, and I think it was inherited from Lennart's program
transformations.]
-Jan-Willem Maessen
On Jan 12, 2009, at 12:47 PM, Max Bolingbroke wrote:
2009/1/12 Jan-Willem Maessen jmaes...@alum.mit.edu:
On Jan 12, 2009, at 9:01 AM, Duncan Coutts wrote:
No because the current definition are recursive and ghc cannot
inline
recursive functions.
Then the map can be inlined
that there is
no documentation of any kind at all for the Monoid instance of
Ordering; how were we supposed to know this behavior existed in the
first place, except by hunting down the source code for the instance
declaration?
-Jan-Willem Maessen
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be worth trying. Understanding the current GC
strategy would make it easier to make the right tradeoffs here; we
expect n insertions will touch O(n) subtables, so repeated insertion
will make life worse if we're not careful.
-Jan-Willem Maessen
plus check GC times for every version: +RTS
detector.]
-Jan-Willem Maessen
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On Oct 12, 2008, at 6:19 AM, Jon Harrop wrote:
On Saturday 11 October 2008 17:45:39 John A. De Goes wrote:
I have strong interest in hosting GHC on the JVM. And I suspect it
would be good for the Haskell community, as the JVM already runs on
nearly every machine known to man, has a wealth of
On Aug 27, 2008, at 4:31 PM, Bulat Ziganshin wrote:
Hello Jan-Willem,
Wednesday, August 27, 2008, 4:06:11 PM, you wrote:
One obvious way to make non-modifiable hash tables useful is to eat
your own tail non-strictly--- aggregate a set of hash table entries,
construct a hash table from them,
On Aug 27, 2008, at 3:41 AM, Bulat Ziganshin wrote:
Hello haskell-cafe,
solving one more task that uses English dictionary, i've thought:
why we don't yet have pure hashtable library? There is imperative
hashtables, pretty complex as they need to rebuild entire table as
it grows. There
Double# - Int64#...
-Jan-Willem Maessen
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http://projectfortress.sun.com/Projects/Community
Let me assure the readers there's nothing confidential or privileged
about Christine's talk! :-) It is, after all, an open source project.
-Jan-Willem Maessen
Project Fortress, Sun Microsystems Laboratories
[who will be off teaching Fortress
Haskell
code: Haskell modules are not ML modules.
-Jan-Willem Maessen
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On Jun 6, 2008, at 12:54 PM, Henning Thielemann wrote:
On Fri, 6 Jun 2008, Achim Schneider wrote:
Jan-Willem Maessen [EMAIL PROTECTED] wrote:
There's one caveat: Always choose descriptive names, even if you are
assuming that you will usually use a qualified import. The
following
On Apr 26, 2008, at 7:41 AM, Adrian Hey wrote:
Jan-Willem Maessen wrote:
On Apr 24, 2008, at 11:33 AM, Adrian Hey wrote:
Also, if you're likely to be using union/intersection a lot you
should
know that Data.Map/Set are very slow for this because they use the
not efficient hedge algorithm
/IntMap of course the split structure of the tree is fixed
(we can think of these as being compressed versions of a complete
binary tree) and union and intersection are quite efficient.
-Jan-Willem Maessen
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to decide whether either of these is implementable in
terms of `orElse`, in such a way that we immediately check the
predicate upon retry before doing anything else. I can't quite make
up my mind whether this is possible or not.
-Jan-Willem Maessen
-- ryan
On Apr 16, 2008, at 4:45 AM, Ketil Malde wrote:
I notice BEA uses something called compressed pointers to get the
64-bit (more registers, etc) benefits without paying the
(cache-thrashing) cost.
But only if you're not *actually* using a 64-bit address space. From
their own documentation:
? A candidate for standardization, surely?
-Jan-Willem Maessen
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a better/different benchmark suite for STM?
Good question. Because we tend to eschew mutable state in Haskell,
I'd expect the characteristics of such an application to be *very*
different.
-Jan-Willem Maessen
Thanks,
Tom
[1] http://openquark.org/Open_Quark/Welcome.html
[2] http
of whenever-I-get-time, along
with generic splittable supplies. Note that getting the laziness
right is somewhat tricky.
-Jan-Willem Maessen
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floating value
for infinity (exploiting IEEE arithmetic in a simple, easily-
understood way). If I'm right, it probably wasn't intended to be used
as a Rational at all, nor to be exploited by user code.
-Jan-Willem Maessen
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On Feb 1, 2008, at 9:41 AM, Alfonso Acosta wrote:
You'd probably be interested to read
http://www.cs.chalmers.se/~koen/pubs/entry-asian99-lava.html
It is indeed an interesting paper (that I've read and referred to
several times over the years). But it's tricky to get right in
practice!
contains a reference, or that they
are densely numbered, so we end up having to look them up in some
fashion (though using a hash table can be reasonably quick if we
uniquely number nodes).
-Jan-Willem Maessen
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. If you want to hear an entertaining story some day, ask me
in person about my Ph.D. thesis defense.
-Jan-Willem Maessen
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of systems where read barriers
are nearly free. Better still, everything that's been learned about
and published in Java-land carries across to Haskell (though the
tradeoffs in eg mutation behavior are often different).
-Jan-Willem Maessen
On Dec 5, 2007, at 3:58 AM, Simon Marlow wrote:
Jan-Willem Maessen wrote:
Consider this:
do
x - newIVar
let y = readIVar x
writeIVar x 3
print y
(I wrote the let to better illustrate the problem, of course you
can inline y if you want). Now suppose the compiler decided
On Nov 29, 2007, at 6:19 PM, Stefan O'Rear wrote:
On Thu, Nov 29, 2007 at 09:10:16PM +, Andrew Coppin wrote:
Sebastian Sylvan wrote:
On Nov 29, 2007 6:43 PM, Andrew Coppin [EMAIL PROTECTED]
wrote:
I don't understand the ST monad.
...[and ST uses language extensions Andrew doesn't
) then
removingIndirections (ptrs closureData ! 0)
else
k a
simpleIsWHNF :: a - IO Boolean
simpleIsWHNF = fmap (isConstr . tipe) . getClosureData
isWHNF = removingIndirections simpleIsWHNF
-Jan-Willem Maessen
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, though the fundamental use of a foldP-
like operation hasn't changed over time).
-Jan-Willem Maessen
Longtime Haskell Hacker
Fortress Library Developer
PS - By the way, working on Generators has increased my suspicion
that comprehensions do NOT have a naturally monadic structure (which
.
On 8/13/07, Jan-Willem Maessen [EMAIL PROTECTED] wrote:
The problem here is that while Cilk spawns are incredibly cheap,
they're still more than a simple procedure call (2-10x as expensive
if my fading memory serves me rightly). Let's imagine we have a
nice, parallelizable computation that we've
. For the latter problem
there simply is no magic bullet.
-Jan-Willem Maessen
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using only 1 thread, you can expect to wait a
long time for simulation results.
Also, these things tend to require an awful lot of care and feeding.
[Full disclosure: I don't personally work with Simics or its ilk, but
my colleagues do.]
-Jan-Willem Maessen
if it finds a zero.
z is a left zero of op if for all x, z `op` x = z.
This isn't the only time foldr will terminate early, but it is an
important one.
-Jan-Willem Maessen
Dan
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the result was faster than Data.Map, but not by much, and
using strings probably wipes out that advantage vs. tries.
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in each
dimension, you should be able to do this using linear programming.
This will yield non-integer coordinate bounds which you can narrow as
appropriate.
-Jan-Willem Maessen
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maintained a symbol table and looked up
expression occurrences in it as you parsed). That said, I wouldn't
necessarily try to structure my parser that way.
-Jan-Willem Maessen
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of all sorts, by the
way.
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like the Diesel in Davis Sq.
I've given this a teensy bit of thought, but I've had too many other
fish to fry lately. :-)
-Jan-Willem Maessen
On Apr 27, 2007, at 11:22 AM, Seth Gordon wrote:
Donald Bruce Stewart wrote:
P.S. Some obvious user group candidates, in my opinion, would
. The concurrency +
unsafePerformIO mix was trickier than I initially expected, too.
That said, this BDD implementation is pretty similar to the
performance behavior you'd get from Data.IntSet (where the bits of
your int correspond to the True/False values of your variables).
-Jan-Willem
On Apr 12, 2007, at 9:39 PM, Matthew Brecknell wrote:
Jan-Willem Maessen:
Interestingly, in this particular case what we obtain is isomorphic
to constructing and reversing a list.
Jan-Willem's observation also hints at some interesting performance
characteristics of difference lists. It's
the same bug, for much the same reason).
-Jan-Willem Maessen
Edsko
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with Fortress we are looking at RULES-like approaches, but they
founder quickly because the kind of problems David is trying to solve
are 90% of what our programmers want to do.
-Jan-Willem Maessen
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('.')
are not internalized correctly in Haskell.
And this is why some of us think that adding polymorphic seq to
Haskell was a mistake. :(
I've often wondered why seq is the primitive and not $!
Would this solve the problem?
Sadly, no:
seq = (const id $!)
-Jan-Willem Maessen
Is there any solution that would
with * somehow).
-Jan-Willem Maessen
[PS: hadn't seen the LNCS reference before, thanks to Jacques for
sending that along.]
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them as you go. I'm quite enjoying the
escH paper, but I get through about a column per day between
compiles. :-)
-Jan-Willem Maessen
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. Thus one single bad declaration can tear a
gaping
hole into an otherwise perfectly nice and consistent DAG of precedence
order relations, possibly invalidating a whole lot of code.
Requiring parenthesization solves these problems in a stroke.
-Jan-Willem Maessen
who can't reliably
in an amortized sense.
-Jan-Willem Maessen
Perhaps I would be possible to use some trick to rebalance an existing
tree to account for what's currently evaluated. But it could be very
tricky to get it right and it would certainly go beyond Haskell 98.
Best regards
Tomasz
On Sep 18, 2006, at 4:47 AM, Einar Karttunen wrote:
On 18.09 01:23, Josef Svenningsson wrote:
On 9/17/06, Jan-Willem Maessen [EMAIL PROTECTED] wrote:
You can associate a unique name with each traversal, and store a set
of traversals at each node (instead of a mark bit). But this set
grows
to concurrently traverse a graph, you need to keep separate
cycle-avoidance state for each traversal. Using TVars doesn't change
that basic algorithmic detail.
And is there a better way of getting TVar identity than
StableNames?
Would that there were!
-Jan-Willem Maessen
- Einar Karttunen
.
-Jan-Willem Maessen
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multiplication algorithm turns out to be exciting. :-)
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On Mar 28, 2006, at 1:02 AM, Tomasz Zielonka wrote:
On Mon, Mar 27, 2006 at 03:10:18PM -0800, Greg Fitzgerald wrote:
hold a part of the data in memory while you show the first one,
Here would be a better example then.
f lst = show (sum (filter ( 1) lst), sum (filter ( 2) lst))
It
intervals).
That said, I don't try to do everything at the type level---it became
too tiring, with not enough plausible benefit.
Any and all: Drop me a line if you are interested, it's a stack of
3-4 modules and at best half-baked. I'd just gotten a mostly-
complete version.
-Jan-Willem
for ignore. I can see
taste arguments in either direction, but really the language ought to
pick an alternative and use it everywhere (including for ).
-Jan-Willem Maessen
John
--
John Meacham - ⑆repetae.net⑆john⑈
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On Feb 15, 2006, at 3:42 AM, Ketil Malde wrote:
Not sure how relevant this is, but I see there is a recently released
hash library here that might be a candidate for FFIing?
https://sourceforge.net/projects/goog-sparsehash/
The real issue isn't the algorithms involved; I saw the best
as work on the type system etc?
I would answer resoundingly that there is still a good deal to
learn / perfect in the compilation technology, but there's been a
lack of manpower/funding to make it happen.
-Jan-Willem Maessen
Regards, Brian
On Feb 3, 2006, at 8:16 PM, Brian Hulley wrote:
Jan-Willem Maessen wrote:
I pointed out some problems with strict Haskell in a recent talk, but
I think it'd be worth underscoring them here in this forum.
Is the text of this talk or points raised in it available online
anywhere?
snip
.
The use of lists as generators would need to be re-thought (and
probably discarded), idioms involving infinite lists would have to
go, etc., etc. But this is a simple matter of libraries (well, and
which type(s) get(s) to use square brackets as special builtin
notation).
-Jan-Willem
On Jan 4, 2006, at 5:30 AM, Simon Marlow wrote:
On 30 December 2005 01:23, Jan-Willem Maessen wrote:
Probably. The minimum table chunk size was rather large. I have
been experimenting (tests are running even as I type) with alternate
implementations of Data.HashTable. So far the winning
splitAtAndReverseAppend...
-Jan-Willem Maessen
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I was surprised to learn that indexed insertion:
permutations (x:xs) =
[insertAt n x perms | perms - permutations xs,
n - [0..length xs] ]
insertAt :: Int - a - [a] - [a]
insertAt 0 y xs = y:xs
insertAt n y (x:xs) = x:(insertAt (n-1) y xs)
was faster than the
tried thus
far.
I need to get distribution clearance for a bunch of this code from my
employer, and figure out how to package it. The latter may be
tricky, as Data.Hashtable is currently rather intimately tied to a
bunch of rather tricky bits of GHC.
-Jan-Willem Maessen
Second
arrays. Copying such
structures is terribly expensive, or even impossible (imagine copying
a 1PB array). I'd think hard before I used them for, say, cons cells.
Shae: All this is very, very different from eager / optimistic
evaluation.
-Jan-Willem Maessen
generally opposed to wasting good operator and function
names as well as syntactic sugar of any kind on a /concrete/ data
type,
and especially not for stacks aka lists.
Would you be happier if it were the yield operator for iterators?
Yours lazily,
Jan-Willem Maessen
Just my 2 cent.
Ben
On Nov 9, 2005, at 4:46 AM, Ketil Malde wrote:
Sebastian Sylvan wrote:
On 11/8/05, Jan-Willem Maessen [EMAIL PROTECTED] wrote:
Just wanted to let people know that I've been working on improving
Data.HashTable, with the help of Ketil Malde's badly performing code
Always happy to help
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