The GHC documentation says that (evaluate a) is not the same as (a
`seq` return a). Can someone explain the difference to me, or point
me to a place where it is explained?
Mike
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On 9/9/06, Ashley Yakeley <[EMAIL PROTECTED]> wrote:
Is it possible to write nondet?
Yes; it (or something very similar) is discussed here:
http://www.haskell.org/haskellwiki/Timing_out_computations
Hope this helps!
--Tom Phoenix
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Haskell-Ca
Is it possible to write nondet?
nondet :: a -> a -> a
nondet _|_ _|_ = _|_
nondet _|_ q = q
nondet p _|_ = p
nondet p q = p or q
nondet evaluates its arguments in parallel, and returns the first one of
them to evaluate. It's thus a bit different from the "par" of GPH. This
isn't refe
On 2006-09-09, Jón Fairbairn <[EMAIL PROTECTED]> wrote:
> Aaron Denney <[EMAIL PROTECTED]> writes:
>> Meh. Naturals are reasonably useful sometimes, but not often enough, in
>> my opinion. Any sort of numeric hierarchy designed to deal with them
>> would be totally broken from my point of view -
Hello,
Try Don Stewart's ByteString library
(http://www.cse.unsw.edu.au/~dons/fps.html). It is much faster than
the standard Haskell IO and now has lazy.
-Jeff
On 9/9/06, Daniel Fischer <[EMAIL PROTECTED]> wrote:
Hello all,
Now I have an IO-problem, too.
SPOJ problem 41 asks basically to dete
Hello all,
Now I have an IO-problem, too.
SPOJ problem 41 asks basically to determine whether a directed graph allows a
path that uses every edge exactly once. The data from which the graphs are to
be constructed are contained in a (huge) file, every item (number of test
cases, size of test case
Ashley Yakeley wrote:
> Bertram Felgenhauer wrote:
>
>> This is correct according to the IEEE 754 standard, which defines
>> that NaN compares unequal to everything, including itself.
>
> This is numerically useful, perhaps, but nonetheless disturbing. For it
> would be helpful to expect that any
Hi,
I have the following data structures:
import System.Mem.Weak
data Proxy = ...
data Model = Model { _proxiesRef :: !(Ref.T [Weak Proxy]), ...}
(Ref.T is just a lifted IORef)
I was writing code like:
createProxy :: MonadIO m => Model -> m Proxy
createProxy Model{_proxiesRef =
Thanks a lot. That's what I need.
On 9/8/06, J. Garrett Morris <[EMAIL PROTECTED]> wrote:
I've always used:
roundn n f = fromIntegral (round (f * 10 ^ n)) / 10 ^ n
I may have missed some bugs or subtleties of floating point numbers, though.
/g
On 9/8/06, Sara Kenedy <[EMAIL PROTECTED]> wrot
On 9/9/06, Brian Hulley <[EMAIL PROTECTED]> wrote:
Yes: tuples, contexts, set of classes to derive from in a deriving clause,
module export list, import directives.
I guess I thought of most of those as a sort of grouping, without
really thinking about it. But I suppose you are right that they
Michael Shulman wrote:
On 09 Sep 2006 11:17:52 +0100, Jón Fairbairn
<[EMAIL PROTECTED]> wrote:
Right about the start of the design of Haskell, I proposed
the rule "parentheses should only be used for grouping".
I think I would have liked that rule. Are parentheses currently used
for anything
Jón Fairbairn wrote:
"Brian Hulley" <[EMAIL PROTECTED]> writes:
I imagine that almost every editor at least does lexical
fontification, and if so, then I don't think there could be
much confusion in practice between these uses of '-'.
I think that unnecessarily disadvantages people with poorer
No, lisp doesn't have currying, but of course I knew that Haskell
does. I think my thought processes went something like this: I want
to partially apply "<", but < is an infix operator in Haskell, so
first I have to convert it to the function (<) written with prefix
notation and then partially ap
On Sat, 2006-09-09 at 11:17 +0100, Jón Fairbairn wrote:
. . .
> I should think so. But does lisp have currying these days?
> (lessp 0 1) ==> T
> but (lessp 0) would be an error, wouldn't it?
For Scheme, R5RS, Section 6.2.5 specifies that "<" and ">" take two or
more arguments, and PLT Scheme r
Il Sat, Sep 09, 2006 at 09:58:03AM -0700, Jason Dagit ebbe a scrivere:
> Maybe "...use -package HaXml interactively with GHCi..." (That's from
> the HaXml website.)
I'm using "-package HaXml", obviously, otherwise the module would not
load.
What I do not understand is that "unresolved symbol" mes
On 9/9/06, Andrea Rossato <[EMAIL PROTECTED]> wrote:
Hello!
[snip]
During interactive linking, GHCi couldn't find the following symbol:
TextziXMLziHaXmlziParse_xmlParse_closure
This may be due to you not asking GHCi to load extra object files,
archives or DLLs needed by your current session.
Hello Andrea,
Saturday, September 9, 2006, 4:17:36 PM, you wrote:
> During interactive linking, GHCi couldn't find the following symbol:
> TextziXMLziHaXmlziParse_xmlParse_closure
as a workaround, you can try to run your program using runghc and
compile it using "ghc --make"
--
Best regards,
Daniel Fischer wrote:
> Another thing:
> Would it be a good idea to create derived Read instances that could parse
> both, "A `And` A" and "And A A" ?
> Since 6.4.2 parses the former and 6.2.2 parses the latter that should be
> possible, I believe (and both forms are accepted at the ghci prompt)
"Brian Hulley" <[EMAIL PROTECTED]> writes:
> Jón Fairbairn wrote:
> > [1] “-” is a varsym. The logical way of achieving what you
> > suggest (ie -1 -2... as constructors for Integer) would be
> > to make it introduce a consym the way “:” does, but then it
> > couldn't be an infix operator anymore.
Aaron Denney <[EMAIL PROTECTED]> writes:
> On 2006-09-08, Jón Fairbairn <[EMAIL PROTECTED]> wrote:
> > Why shouldn't Naturals be more primitive than Integers?
>
> Certainly they're more primitive. Too primitive to have reasonable
> algebraic properties.
Hmph. Naturals obey (a+b)+c == a+(b+c),
Aaron Denney <[EMAIL PROTECTED]> writes:
> Jón Fairbairn <[EMAIL PROTECTED]> wrote:
> > I think the present design is wrong because we don't have a
> > type for naturals.
>
> Meh. Naturals are reasonably useful sometimes, but not often enough, in
> my opinion. Any sort of numeric hierarchy des
Aaron Denney <[EMAIL PROTECTED]> writes:
> We already have this great syntax, parsing semanticsi for precedence,
> and so forth for declaring infix operators. Couldn't we add to that
> slightly by declaring postfix operators as well? Actually, declaring a
> unary operator infix yielding a postfi
On 2006-09-08, Brian Hulley <[EMAIL PROTECTED]> wrote:
> Leaving aside the question of negative literals for the moment, what's so
> special about unary minus that it warrants a special syntax? For example in
> mathematics we have x! to represent (factorial x), which is also an
> important funct
On 2006-09-08, Jón Fairbairn <[EMAIL PROTECTED]> wrote:
> "Brian Hulley" <[EMAIL PROTECTED]> writes:
>> In the context of programming, I don't see the problem of
>> just thinking of the integers as a primitive built-in data
>> type which contains some range of positive and negative
>> integers whi
"Cale Gibbard" <[EMAIL PROTECTED]> writes:
> Another thing to note is that all the natural literals are not, as one
> might initially think, plain values, but actually represent the
> embedding of that natural number into the ring (instance of Num), by
> way of 0 and 1.
Excellent point, and good
On Sat, Sep 09, 2006 at 12:57:56AM -0400, Cale Gibbard wrote:
> Num itself needs to be split, but we can't do it sanely without
> something like class aliases.
I think that a finer grain numeric hierarchy, while retaining Num, etc,
is feasible without changing the language: unlike the case of mona
Hello!
probably it's me, but I cannot understand what I'm doing wrong.
I'm trying to learn HaXml. I've never used it before and I never did
xml processing in Haskell. So I'm a total newbie!!
I downloaded and compiled. Everything seems fine. I'm also able to run
some examples in the related direc
"Michael Shulman" <[EMAIL PROTECTED]> writes:
> A propos of sections of subtraction, and thence to sections of other
> noncommutative operators, as a Haskell newbie I was surprised to
> discover (the hard way!) that
>
> (< 0)
>
> and
>
> ((<) 0)
>
> mean different things. I had typed (< 0) wh
On 09/09/06, Cale Gibbard <[EMAIL PROTECTED]> wrote:
When I first ran into the problem with (-) and
sections, I was slightly annoyed with having to write (+ (-1))
Let's not forget that there is the library function 'subtract' for
this purpose. What you wrote could be written as (subtract 1), wh
Hello Peter,
Friday, September 8, 2006, 6:03:36 PM, you wrote:
> I am stumped again. The following code generates the error "ERROR
> file:.\Cube.hs:12 - An instance of IArray UArray a is required to derive Eq
> (Cube a b)" in Hugs. But I did specify the IArray UArray k constraint. So
> what is wr
A propos of sections of subtraction, and thence to sections of other
noncommutative operators, as a Haskell newbie I was surprised to
discover (the hard way!) that
(< 0)
and
((<) 0)
mean different things. I had typed (< 0) when I meant to type ((<)
0). No compiler errors, of course, and I ha
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