Brandon Michael Moore [EMAIL PROTECTED] writes:
Or was that supposed to be composition of a constructor with a function, A
. f? Function composition, and higher order functions in general are
likely to confuse an imperative programmer, but I think there isn't much
syntax can do there.
I
Shawn P. Garbett [EMAIL PROTECTED] writes:
For the How do I write a map function in Haskell?, how about an answer of
drop course immediately before your GPA is impacted further.
:-)
Of course, this comes from someone whos made some stupid posts to this list,
and gotten polite answers
Antony Courtney [EMAIL PROTECTED] writes:
-- Example: format a list of strings, using a comma as a seperator:
mkSepStr :: [String] - String
mkSepStr xs = foldrs (\x s - x ++ , ++ s) xs
t0 = mkSepStr [] -- ==
t1 = mkSepStr [hello]-- == hello
t2 = mkSepStr
Tn X-10n [EMAIL PROTECTED] writes:
change :: String - Bool
change 1 = True
change 0 = False
conv :: [String] - [Bool]==unable to declare [[Bool]]
Again: a String is a list of ?
-kzm
--
If I haven't seen further, it is by standing in the footprints of giants
Tn X-10n [EMAIL PROTECTED] writes:
i am new wif haskell, i would like to know how can i get a list of
string and convert it to a list of a list of bool
[String]- [[Bool]]
What is the definition of a String? (I.e. what is a String a list of?)
Write a function to convert one of these to the
Glynn Clements [EMAIL PROTECTED] writes:
Does anyone know of a good editor in Linux to do this or the commands for
Emacs etc. that can be used from within Hint to achieve [jumping to
lines with errors automatically]?
Emacs and XEmacs allow you to go to a specified line using +number,
If you
Marcin 'Qrczak' Kowalczyk [EMAIL PROTECTED] writes:
Dnia pon 11. sierpnia 2003 00:49, Wolfgang Jeltsch napisa:
The main problem is that you need binary I/O. Haskell 98 only provides text
I/O.
You don't need binary I/O for UTF-8 now; because implementations use
ISO-8859-1, UTF-8 octets can
Ashley Yakeley [EMAIL PROTECTED] writes:
There should be a separate syntax for that. As it stands, the string
3.1415926536 unambiguously specifies a rational number. Perhaps
something like 3.1415926536... should be interpreted as the 'simplest'
rational that agrees with the given digits,
David Roundy [EMAIL PROTECTED] writes:
The problem is trying to figure out where I'm doing this. Unfortunately, I
have only been able to see this error on a rather large test repository,
where it takes seven minutes for the test to show up.
Hah! *My* program can take hours before it
Peter Simons [EMAIL PROTECTED] writes:
Mark Carroll writes:
Perhaps I'll have to look out for a library for parsing e-mail
messages.
I have written a set of parser functions for RFC 2822 messages, which
should do exactly that. It's not finished yet, but if you're
interested in using the
Joe English [EMAIL PROTECTED] writes:
Sengan Baring-Gould wrote:
http://www.catb.org/~esr/writings/taoup/html/ch01s06.html
states that debugging often occupies three-quarters or more
of development time. I don't think that is my experience
in Haskell... more like 1/4 at most. I was
Simon Marlow [EMAIL PROTECTED] writes:
OTOH, doing lots of small (//) seems to be faster than doing a few
large ones (containing the same updates). Go figure.
That's bizarre. Perhaps the results are obscured by some other
optimisations which are happening.
It is probably an operator
Simon Marlow [EMAIL PROTECTED] writes:
That's because currently large objects aren't included in the profile.
Okay, I didn't know that.
I'll look into fixing this.
Great! But just knowing about it also helps a lot.
Since you're on the line, could you confirm or deny that the (//)
operator
[EMAIL PROTECTED] (Ketil Z. Malde) writes:
Hal Daume III [EMAIL PROTECTED] writes:
Yes, (//) is terrible. It *never* tries to update in-place.
Any reason it couldn't be done in-place? (I.e. thaw, update all, and
freeze again) Am I missing something -- Could partial results be
used
[EMAIL PROTECTED] (Ketil Z. Malde) writes:
[EMAIL PROTECTED] (Ketil Z. Malde) writes:
Hal Daume III [EMAIL PROTECTED] writes:
Yes, (//) is terrible. It *never* tries to update in-place.
replace :: UArray Int Int - [(Int,Int)] - UArray Int Int
replace a p = runST (thaw a = \u
[EMAIL PROTECTED] (Ketil Z. Malde) writes:
replace :: UArray Int Int - [(Int,Int)] - UArray Int Int
replace a p = runST (thaw a = \u - update u p freeze u)
update :: STUArray s Int Int - [(Int,Int)] - ST s ()
update u ps = mapM_ (uncurry (writeArray u)) ps
(I'll be right back
Hal Daume III [EMAIL PROTECTED] writes:
[snip my functions that use the ST monad to do (//)]
You shouldn't try to write these functions. You should do all array
modifications within the ST monad, rather than looking for a pure
solution.
All right, but why? It seems an obvious trick, take
Hal Daume III [EMAIL PROTECTED] writes:
Any reason it couldn't be done in-place? (I.e. thaw, update all, and
freeze again) Am I missing something -- Could partial results be
used, the update list be infinite, or anything like that?
I believe that's essentially what normal arrays are doing,
Hi
Having written a suffix-array based program using lists, I thought I'd
speed it up a bit, and perhaps more importantly, save space, using
arrays. Basically, the problem is to sort all suffixes of a string,
represented as an array of offsets, alphabetically.
(Does anybody have such code?
Hal Daume III [EMAIL PROTECTED] writes:
Yes, (//) is terrible. It *never* tries to update in-place.
Any reason it couldn't be done in-place? (I.e. thaw, update all, and
freeze again) Am I missing something -- Could partial results be
used, the update list be infinite, or anything like
Hi,
experimenting with QuickCheck, I write
instance (Arbitrary e) = Arbitrary (Array Int e) where
arbitrary = undefined
and I get:
|Illegal instance declaration for `Arbitrary (Array Int e)'
| (The instance type must be of form (T a b c)
|where T is not a synonym,
Simon Marlow [EMAIL PROTECTED] writes:
That may well be true, and I've heard others suggest that the library is
inconvenient. I'm trying to get at whether that is due to current bugs
in the implementation, or whether the design is fundamentally broken.
Well; perhaps the right thing to do is
Peter Simons [EMAIL PROTECTED] writes:
CalendarTime [...]
TimeDiff [...]
I briefly looked at the Posix module [...]
non-standard. *sigh* [...]
Any suggestions what I could do?
Yes.
I think it is widely agreed that the time and date structures in the
standard libraries are
Ingo Wechsung [EMAIL PROTECTED] writes:
class Keyed a where { -- Type a is keyed if it has a key function.
key :: Ord b = a - b; -- key is a function, that, when applied to
a yields some b that is comparable
}
But it isn't obvious what b is supposed to be. Try multi-parameter
Simon Marlow [EMAIL PROTECTED] writes:
(My preju^H^Hference would be to store a date-time internally in a
posix-like manner (seconds,microsecond since the epoch).)
I'm still not sure I understand why the Time library is considered to be
broken
I was probably a bit quick on the trigger
Mark Carroll [EMAIL PROTECTED] writes:
On 17 Dec 2002, Ketil Z. Malde wrote:
Ah - I was never sure what to make of that - I normally just use the GHC
online Haddockised stuff which tells me no more than the type signatures,
but I suppose split must be more than (\x-(x,x))!
Well, as SPJ
Mark Carroll [EMAIL PROTECTED] writes:
The dice function gives you back the new state of the rng which maybe
you should keep around to start the next set of rolls with. (main throws
it away with snd.) I'd certainly be interested to see how this could be
written more nicely. I avoided making
Mark Carroll [EMAIL PROTECTED] writes:
On 17 Dec 2002, Ketil Z. Malde wrote:
(snip)
dice :: Integer - StdGen - [Integer]
dice n g = take n $ randomRs (1,6) g
Can we still do this concisely and get the new state of the rng back out
the other end after the die has been thrown
matt hellige [EMAIL PROTECTED] writes:
I would
PREFER if haskell enforeced a strict distinction between spaces and
tabs for layout purposes, i.e., this:
let x = y
^I z = q
^Iw = l
in ...
should be an error.
Simon¹ is usually very positive to adding enhancements, if this really
John Meacham [EMAIL PROTECTED] writes:
rather than start layout blocks right after the 'let' 'do' or 'where',
put them on the next line with one more tabstop than the current
line.
I've also a bit baffled by all the people apparently struggling with
layout; I realize the rules are a bit
Malcolm Wallace [EMAIL PROTECTED] writes:
Ingo Wechsung [EMAIL PROTECTED] writes:
I wonder if the compiler could check, if all possible combinations have
been checked in a pattern match.
In ghc, use the compile-time option -fwarn-incomplete-patterns
Is there a warning to warn if a block is
Ingo Wechsung [EMAIL PROTECTED] writes:
Simon wrote:
There's no reason not to use 8 column tab stops, so please don't do it.
Ok, if it just looks better to me is no reason,
Tabs and spaces aren't visually distinguishable, so I'm not sure why
you conclude that looks don't matter.
As has
Hi
I was just browsing around on comp.arch a bit, and there was this
discussion about various ways to represent non-integer numeric
values.
It seems one could easily (I'll get back to that in a moment)
calculate the fractional part of numbers lazily, generating the needed
precision, and
Ashley Yakeley [EMAIL PROTECTED] writes:
At 2002-10-10 01:29, Ketil Z. Malde wrote:
I realize it's probably far from trivial, e.g. comparing two equal
numbers could easily not terminate, and memory exhaustion would
probably arise in many other cases.
I considered doing something very
Scott J. [EMAIL PROTECTED] writes:
I have a question. Why are sets not implemented in Haskell?
What do you mean? Isn't
http://www.haskell.org/ghc/docs/latest/html/hslibs/set.html
sufficient? (Remember to tell GHC '-package data')
-kzm
--
If I haven't seen further, it is by
Shawn P. Garbett [EMAIL PROTECTED] writes:
I've come up with three different methods of approach to solve the same
problem in haskell. I would like to compare the three in terms of reductions,
memory usage, and overall big O complexity.
What's the quickest way to gather these stats?
I
Matthias [EMAIL PROTECTED] writes:
Type Constructors and data Constructors are in separate
namespaces. [example]
But according to the chapter (2.2.1) Recursive Types i see the
polymorphic definition of a tree is:
data Tree a = Leaf a | Branch (Tree a) (Tree a)
where (Tree a) is
Brian Tawney [EMAIL PROTECTED] writes:
REQUEST FOR ASSISTANCE- STRICTLY CONFIDENTIAL
This is a common scam.
It is also a common spam. How about closing the list for
non-subscribers?
-kzm
--
If I haven't seen further, it is by standing in the footprints of giants
Koen Claessen [EMAIL PROTECTED] writes:
Suppose I have a function f which is defined to
have 3 arguments:
f x y z = ...
Now, when I want to partially apply f to two arguments, say
1 and 2, I can say this:
... (f 1 2) ...
However, if I want to leave out the middle argument, I
Mark Carroll [EMAIL PROTECTED] writes:
One criticism I've received of the suggestion that we use Haskell in our
business is that some particularly large clients will demand code in some
'standard' language
How big a project would it be to translate, say, from Haskell to C
or Java?
How
Michael Ruth [EMAIL PROTECTED] writes:
start:: IO()
start = do {
putStr Enter a filename: ;
theFile - getLine;
myfile - openFile theFile ReadMode;
myList - getInput myfile;
myDates - stripSpaces myList;
myDates - qSort myDates;
myList -
David Feuer [EMAIL PROTECTED] writes:
Sorting is probably easiest if you use the standard sort function. I'm
still kind of interested in whether anyone has done work on which
purely-functional sorts are efficient, and particularly which ones are
efficient in GHC.
I've implementing a
Zhe Fu [EMAIL PROTECTED] writes:
But when there is a type error: [...]
How can I solve it?
I often remove the type declaration, load the code in GHCi or Hugs,
and do a :t my_function. The interpreter then tells me what /it/
thinks is the type, and quite often it is smarter than I am :-)
Hi,
I'm a bit puzzled by this observatio that I made. I have a function
that, pseudocoded, lookes somewhat like
f i as bs cs = ins i (f (i+1) as) ++ ins i (f (i+1) bs) ++ ins i (f (i+1) cs)
where ins i = manipulates the first element of the list
Now, without the ins'es, the
Jay Cox [EMAIL PROTECTED] writes:
where ins i = manipulates the first element of the list
if you mean that (ins i) :: [a] - [a] manipulates the first element of
the list it takes then of course it is strict. because in
It is strict in the head of the list, yes. I.e. it is defined
Simon Marlow [EMAIL PROTECTED] writes:
Can we also rely on destructive updates for the monadic arrays?
In GHC, yes :-)
Goodie!
One more question: I imagine arrays give an opportunity to optimize by
unboxing the contained type -- any chance of that? How much space
would an array of Chars
Jorge Adriano [EMAIL PROTECTED] writes:
Anyway, I was coding some simple GA, and as you probably know I need to use
random values. The most elegant way I could think of was to generate some
[...]
Monads! (right?)
Well, I suppose so. Generally speaking.
But, you might want to consider
David Feuer [EMAIL PROTECTED] writes:
1. Why can't [instances] be hidden in module imports/exports?
The way I see it, an instance declaration is an assertion that a
certain data type supports a certain set of operations. Thus, if the
data type and the operations on it are in scope, it makes
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