John Goerzen [EMAIL PROTECTED] writes:
I'm looking for libraries / interfaces to these systems from Haskell:
LDAP
ncurses
zlib (the one in darcs doesn't suit my needs)
bz2lib
I once wrapped ncurses (incomplete), zlib and bz2lib.
http://sourceforge.net/projects/qforeign/
It's quite old
Robert Dockins [EMAIL PROTECTED] writes:
More than you would think, if you follow the conventions of modern
unix shells. eg, foo/.. is always equal to .,
For the OS it's not the same if foo is a non-local symlink.
Shells tend to resolve symlinks themselves on cd, and cd .. means
to remove the
John Meacham [EMAIL PROTECTED] writes:
too bad we can't do things like
#if exists(module System.Path)
import System.Path
#else
...
#endif
I still find it perplexing that there isn't a decent standard haskell
preprocessor
For my language Kogut I designed a syntax
ifDefined
Stefan Monnier [EMAIL PROTECTED] writes:
OTOH I like the abc shorthand because it's both obvious and
unambiguous (as long as the return value of can't be passed as an
argument to , which is typically the case when the return value is
boolean and there's no ordering defined on booleans).
Stefan Monnier [EMAIL PROTECTED] writes:
The various UTF encodings do not have this particular problem; if a UTF
string is valid, then it is a unique representation of a unicode string.
However, decoding is still a partial function and can fail.
And while it is partly true, it is qualified
Glynn Clements [EMAIL PROTECTED] writes:
Then of course there's the issue that Win32 edge
labels are Unicode, while Posix edge labels are [Word8]. Hmm.
Strictly speaking, they're [CChar], but I doubt that anyone will ever
implement Haskell on a platform where a byte isn't 8 bits wide.
On
David Roundy [EMAIL PROTECTED] writes:
No, it's not Unix-specific, it's portable. If you want to write
portable C code, you have to use the standard library, which means
that file names are represented as Ptr CChar.
I disagree. We are talking about portable Haskell, not portable C.
The
Glynn Clements [EMAIL PROTECTED] writes:
And it isn't a theoretical issue. E.g. in an environment where EUC-JP
is used, filenames may begin with ESC$)B (designate JISX0208 to G1),
or they may not (because G1 is assumed to contain JISX0208 initally).
I think such encodings are never used as
Aaron Denney [EMAIL PROTECTED] writes:
Better yet would be to have the standard never allow the BOM.
If I could decide, I would ban the BOM in UTF-8 altogetger, but I'm
afraid the Unicode Consortium doesn't want to do this.
Miscosoft Notepad puts a BOM in UTF-8 encoded files.
--
__(
Graham Klyne [EMAIL PROTECTED] writes:
How can it make sense to have a BOM in UTF-8? UTF-8 is a sequence of
octets (bytes); what ordering is there here that can sensibly be
varied?
The *name* BOM doesn't make sense when applied to UTF-8, but some
software uses UTF-8 encoded U+FEFF it as a
Peter Simons [EMAIL PROTECTED] writes:
http://cryp.to/pathspec/PathSpec.hs
There also is a function which changes a path specification
into its canonic form, meaning that all redundant segments
are stripped.
It's incorrect: canon (read x/y/.. :: RelPath Posix) gives x,
yet on Unix they
Ketil Malde [EMAIL PROTECTED] writes:
The Haskell functions accept or return Strings but interface to OS
functions which (at least on Unix) deal with arrays of bytes (char*),
and the encoding issues are essentially ignored. If you pass strings
containing anything other than ISO-8859-1, you
Josef Svenningsson [EMAIL PROTECTED] writes:
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.
I'm trying to understand the semantics and implementation of bound threads
basing on the conc-ffi paper and others.
Since the main thread is bound, and unbound threads are never executed
on an OS thread which has some Haskell thread bound, this would imply
that when the main thread spawns a
Wolfgang Thaller [EMAIL PROTECTED] writes:
Since the main thread is bound, and unbound threads are never executed
on an OS thread which has some Haskell thread bound, this would imply
that when the main thread spawns a Haskell thread and they synchronize
a lot with each other using MVars, the
Simon Marlow [EMAIL PROTECTED] writes:
Is it important which thread executes Haskell code (I bet no) and
unsafe foreign calls (I don't know)? If not, couldn't the same OS
thread execute code of both threads until a safe foreign call is made?
Actually in a bound thread, *all* foreign calls
Marcin 'Qrczak' Kowalczyk [EMAIL PROTECTED] writes:
Why is the main thread bound?
I can answer myself: if the main thread is unbound, the end of the
program can be reached in a different OS thread, which may be a
problem if we want to return cleanly to the calling code.
I've now implemented
Benjamin Franksen [EMAIL PROTECTED] writes:
Producer/consumer ping-pong is 15 times slower between threads
running on different OS threads than on two unbound threads.
Which OS?
Linux/NPTL.
A context switch which changes OS threads involves:
setitimer
pthread_sigmask
Simon Marlow [EMAIL PROTECTED] writes:
I've now implemented a threaded runtime in my language Kogut, based
on the design of Haskell. The main thread is bound. The thread which
holds the capability performs I/O multiplexing itself, without a
separate service thread.
We found that doing this
Wolfgang Thaller [EMAIL PROTECTED] writes:
Indeed, my brain is melting, but I did it :-)
Congratulations. How about we found a Bound-thread-induced brain
melt victims' support group?
The melt was entertaining :-)
Besides simplicity, one of the main reasons for moving our select()
call
Duncan Coutts [EMAIL PROTECTED] writes:
It doesn't affect functions added by the hierarchical libraries,
i.e. those functions are safe only with the ASCII subset. (There is
a vague plan to make Foreign.C.String conform to the FFI spec,
which mandates locale-based encoding, and thus would
Glynn Clements [EMAIL PROTECTED] writes:
It should be possible to specify the encoding explicitly.
Conversely, it shouldn't be possible to avoid specifying the
encoding explicitly.
What encoding should a binding to readline or curses use?
Curses in C comes in two flavors: the traditional
John Meacham [EMAIL PROTECTED] writes:
In any case, we need tools to be able to conform to the common cases
of ascii-only (withCAStrirg) and current locale (withCString).
withUTF8String would be a nice addition, but is much less important to
come standard as it can easily be written by end
Glynn Clements [EMAIL PROTECTED] writes:
The (non-wchar) curses API functions take byte strings (char*),
so the Haskell bindings should take CString or [Word8] arguments.
Programmers will not want to use such interface. When they want to
display a string, it will be in Haskell String type.
Glynn Clements [EMAIL PROTECTED] writes:
E.g. Gtk-2.x uses UTF-8 almost exclusively, although you can force the
use of the locale's encoding for filenames (if you have filenames in
multiple encodings, you lose; filenames using the wrong encoding
simply don't appear in file selectors).
Glynn Clements [EMAIL PROTECTED] writes:
If you provide wrapper functions which take String arguments,
either they should have an encoding argument or the encoding should
be a mutable per-terminal setting.
There is already a mutable setting. It's called locale.
It isn't a per-terminal
Wolfgang Thaller [EMAIL PROTECTED] writes:
Also, IIRC, Java strings are supposed to be unicode, too -
how do they deal with the problem?
Java (Sun)
--
Filenames are assumed to be in the locale encoding.
a) Interpreting. Bytes which cannot be converted are replaced by U+FFFD.
b)
Arjun Guha [EMAIL PROTECTED] writes:
data (Eq v) = EqList v = EqList [v]
I'd like to make it an instance of Functor. However, fmap takes an
arbitrary function of type a - b. I need an Eq constraint on a and
b. Is there any way to do this without creating my own `EqFunctor'
class with
John Goerzen [EMAIL PROTECTED] writes:
I'd say that there are probably no features OCaml has that Haskell
lacks that are worth mentioning.
Its type system has some interesting features: polymorphic variants,
parametric modules, labeled and optional arguments, objects, variance
annotations of
Michael Vanier [EMAIL PROTECTED] writes:
I also learned ocaml before learning haskell, and the biggest single
difference I found is that haskell is a lazy, purely functional language
and ocaml is a strict, mostly functional language.
Indeed.
In contrast to this one, my differences were not
Donn Cave [EMAIL PROTECTED] writes:
I have been able to build ocaml everywhere I have wanted it, including
the native code compiler.
And it builds itself much faster than GHC.
(I couldn't measure how much, because GHC didn't build at all, failing
to find HsBaseConfig.h.in.)
--
__(
Antti-Juhani Kaijanaho [EMAIL PROTECTED] writes:
As far as I know, the last programming language that included
arrays' sizes in their types was Standard Pascal,
There have been many such languages since Standard Pascal. For
example C, C++, C#, Java, Ada, VHDL, and NU-Prolog.
C, C++ and
Sebastian Sylvan [EMAIL PROTECTED] writes:
A list is, for me, more of a logical entity (as opposed to
structural). It's a sequence of stuff not a particular way to
store it (singly-linked, doubly-linked, arraylists etc.).
I call it sequence.
A list is usually a concrete type in a given
Daniel Carrera [EMAIL PROTECTED] writes:
$ nhc98 prng.hs -o prng
I/O error (user-defined), call to function `userError':
In file ./RC4.hi:
1:1-1:6 Found _module_ but expected a interface
GHC and NHC confuse each other with prng.hi files they produce and
examine, in incompatible formats.
Thomas Davie [EMAIL PROTECTED] writes:
I'm not familiar with your C++ example (not being familiar with C++),
but I think that it's a bit of a stretch of the imagination to say
that C introduces a variable of type array of 50 ints, the fact
that this is now an array of 50 integers is never
David Roundy [EMAIL PROTECTED] writes:
No, int (*p)[50] is a multidimensional array, one of the most useless
concepts in C, and is equivalent to int p[50][] (or is it p[][50]...
I always get my matrix subscripts messed up).
No, it's not equivalent to either. Array type are not the same as
Hamilton Richards [EMAIL PROTECTED] writes:
That's not the case in C, C++, Java, or Ada. In C and C++, for
example, given two arrays
int X[50];
int Y[100];
and a function declared as
void P( int a[] )
then these calls
P( X )
P( Y )
are both valid,
Gracjan Polak [EMAIL PROTECTED] writes:
intern :: Ord a = a - a
intern x = unsafePerformIO $ internIO x
iorefset :: Ord a = IORef(Map.Map a a)
iorefset = unsafePerformIO $ do
newIORef $ Map.empty
It will not work because you can't put values of different types as
keys of the same
Brian Hulley [EMAIL PROTECTED] writes:
My final suggestion if anyone is interested is as follows:
1) Use : for types
2) Use , instead of ; in the block syntax so that all brace blocks
can be replaced by layout if desired (including record blocks)
3) Use ; for list cons. ; is already used
Bulat Ziganshin [EMAIL PROTECTED] writes:
i reported only the speed of the buffering transformers. this don't
include speed of char encoding that should be very low at this time.
Recoding will be slow if it's done on top of buffering and if encoding
itself has heavy startup. Buffering should
Bulat Ziganshin [EMAIL PROTECTED] writes:
MQK It should be possible to use iconv for recoding. Iconv works on
MQK blocks and it should not be applied to one character at a time.
recoding don't need any startup.
Calling iconv (or other similar routine) does need startup. And you
really don't
Bulat Ziganshin [EMAIL PROTECTED] writes:
recoding don't need any startup. each vGetChar or vPutChar
just executes one or more vGetByte/vPutByte calls, according to
encoding rules. this should be fast enough
Hmm, your interface for the encoder (String - [Word8]) doesn't
support stateful
Simon Marlow [EMAIL PROTECTED] writes:
I think the reason we set O_NONBLOCK is so that we don't have to test
with select() before reading, we can just call read(). If you don't
use O_NONBLOCK, you need two system calls to read/write instead of
one. This probably isn't a big deal, given that
Simon Marlow [EMAIL PROTECTED] writes:
I agree that a generic select/poll interface would be nice.
We must be aware that epoll (and I think kqueue too) registers event
sources in advance, separately from waiting, which is its primary
advantage over poll.
The interface should use this model
as Double
(the answer may depend on the implementation).
--
Marcin 'Qrczak' Kowalczyk
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Wed, 17 Jan 2001 02:39:53 -0800, Simon Marlow [EMAIL PROTECTED] pisze:
Actually the cpp-style pragma is only recognised if the '#' is in the
leftmost column and is followed by optional spaces and a digit. It's
quite hard to write one of these in a legal Haskell program, but not
impossible.
Tue, 30 Jan 2001 00:13:41 -0800, Ashley Yakeley [EMAIL PROTECTED] pisze:
How do I define downcast?
You can use a non-standard module Dynamic present in ghc, hbc and Hugs
(I don't know if it's compatible with O'Haskell).
--
__(" Marcin Kowalczyk * [EMAIL PROTECTED] http://qrczak.ids.net.pl/
07 Feb 2001 11:47:11 +0100, Ketil Malde [EMAIL PROTECTED] pisze:
If it is useful to have a fine granularity of classes, you can
imagine doing:
class Multiplicative a b c where
(*) :: a - b - c
Then a*b*c is ambiguous no matter what are types of a,b,c and the
or h? Note that Int-Double is not
a subtype of Int-Int, so if h :: (Int-Int)-Bool, then I can't imagine
how h can be applied to something :: Int-Double.
--
Marcin 'Qrczak' Kowalczyk
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Thu, 08 Feb 2001 15:11:21 +0100 (CET), Elke Kasimir [EMAIL PROTECTED] pisze:
However, what is missing for me is something like:
type Comfortable a = (Show a, Eq a, Num a) = a
or
class (Show a, Read a, Eq a) = Comfortable a
instance (Show a, Read a, Eq a) = Comfortable a
I agree and
Thu, 8 Feb 2001 10:51:58 -0500, Peter Douglass [EMAIL PROTECTED] pisze:
The first part of my question (not contained in your reply) is
whether it is feasible to disable a developer's access to the
"unsafe" numerical operations.
import Prelude hiding (quot, rem, (/) {- etc. -})
import
Thu, 8 Feb 2001 21:41:56 +1100, Fergus Henderson [EMAIL PROTECTED] pisze:
Should this define an instance for `foo T'?
(I think not.)
How about if the instance declaration is changed to
instance bar T where
f = 41
-- no definition for f2
Thu, 08 Feb 2001 11:24:49 +, Jerzy Karczmarczuk [EMAIL PROTECTED] pisze:
The implicit coercion of numeric constants: 3.14 -=- (fromDouble
3.14) etc. is sick.
What do you propose instead?
(BTW, it's fromRational, to keep arbitrarily large precision.)
Now, signum and abs seem to be
Fri, 9 Feb 2001 11:48:33 -0500, Dylan Thurston [EMAIL PROTECTED] pisze:
class (Show a, Read a, Eq a) = Comfortable a
instance (Show a, Read a, Eq a) = Comfortable a
Why isn't it legal?
Because in Haskell 98 instance's head must be of the form of a type
constructor applied to type
Sat, 10 Feb 2001 14:09:59 +1300, Brian Boutel [EMAIL PROTECTED] pisze:
Can you demonstrate a revised hierarchy without Eq? What would happen to
Ord, and the numeric classes that require Eq because they need signum?
signum doesn't require Eq. You can use signum without having Eq, and
you can
Sat, 10 Feb 2001 11:25:46 -0500, Dylan Thurston [EMAIL PROTECTED] pisze:
Can you elaborate? What do you mean by signum for functions?
The pointwise signum?
Yes.
Then abs would be the pointwise abs as well, right?
Yes.
That might work, but I'm nervous because I don't know the semantics
Sun, 11 Feb 2001 13:37:28 +1300, Brian Boutel [EMAIL PROTECTED] pisze:
Can you demonstrate a revised hierarchy without Eq? What would
happen to Ord and the numeric classes with default class method
definitions that use (==) either explicitly or in pattern matching
against numeric literals?
Mon, 12 Feb 2001 17:24:37 +1300, Brian Boutel [EMAIL PROTECTED] pisze:
class (Additive a) = Num a where
(*) :: a - a - a
one :: a
fromInteger :: Integer - a
-- Minimal definition: (*), one
fromInteger 0 = zero
fromInteger n | n 0
Sun, 11 Feb 2001 22:27:53 -0500, Dylan Thurston [EMAIL PROTECTED] pisze:
Reading this, it occurred to me that you could explictly declare an
instance of Powerful Integer Integer and have everything else work.
No, because it overlaps with Powerful a Integer (the constraint on a
doesn't matter
arnings about mutual definitions giving bottoms.
--
Marcin 'Qrczak' Kowalczyk
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definitely not constrain
the whole Prelude class system only to have convenient lifting of basic
arithmetic. When it happens that an instance of an otherwise sane class
for functions makes sense, then OK, but nothing more.
--
Marcin 'Qrczak' Kowalczyk
or
records, to multiply a tree by a scalar (btw.: Jn Fairbarn proposes
(.*), I have in principle nothing against, but these operators is used
elsewhere, in other languages, CAML and Matlab; I use (*) ).
Please show a concrete proposal how Prelude classes could be improved.
--
Marcin 'Qrczak
Mon, 12 Feb 2001 12:04:39 +0100 (CET), Marcin 'Qrczak' Kowalczyk
[EMAIL PROTECTED] pisze:
This is my bet.
I changed my mind:
class Eq a = PartialOrd a where -- or Ord
(), (), (=), (=) :: a - a - Bool
-- Minimal definition: () or (=).
-- For partial order
Tue, 13 Feb 2001 18:32:21 -0500, Dylan Thurston [EMAIL PROTECTED] pisze:
I'd like to copy this over to this revised library. But the numeric
constants have to be wrapped in explicit calls to fromInteger.
ghc's docs (the CVS version) say that -fno-implicit-prelude causes
numeric literals
Tue, 13 Feb 2001 18:32:21 -0500, Dylan Thurston [EMAIL PROTECTED] pisze:
Here's a revision of the numerical prelude.
I like it!
class (Real a, Floating a) = RealFrac a where
-- lifted directly from Haskell 98 Prelude
properFraction :: (Integral b) = a - (b,a)
truncate, round
Wed, 14 Feb 2001 23:27:55 -0600, Matt Harden [EMAIL PROTECTED] pisze:
I also wonder: should one be allowed to create new superclasses of an
existing class without updating the original class's definition?
It would not buy anything. You could not make use of the superclass
in default
Fri, 16 Feb 2001 04:14:24 -0800, Simon Peyton-Jones [EMAIL PROTECTED] pisze:
[Incidentally, if this is nhc's behaviour, it's not H98.
The Report (tries to) stress that you get the "fromInt from the actual
standard Prelude" regardless of what is in scope. That's why I'm not
going to make it
Thu, 15 Feb 2001 20:56:20 -0800, William Lee Irwin III [EMAIL PROTECTED] pisze:
literal "5" gets mapped to (fromPositiveInteger 5)
literal "-9" gets mapped to (fromNonZeroInteger -9)
Note that when a discussed generic Prelude replacement
framework is done, and ghc's rules are
Mon, 14 May 2001 20:26:21 -0700, Juan Carlos Arevalo Baeza [EMAIL PROTECTED] pisze:
class (MonadPlus (p s v)) = Parser p where
item :: p s v v
force :: p s v a - p s v a
first :: p s v a - p s v a
papply :: p s v a - s - [(a,s)]
This MonadPlus superclass can't be
I have a case where I don't know how to apply laziness well.
Consider mutable containers (e.g. STArray or a database on disk).
How to iterate over them? I see the following possibilities:
* Give up laziness, provide only a conversion to the list of items.
Since the conversion is monadic, it
Mon, 28 May 2001 17:53:38 -0700, Juan Carlos Arevalo Baeza [EMAIL PROTECTED] pisze:
Uncommenting the type expression above clears the error.
But, why can't the compiler deduce it by itself?
Monomorphism restriction strikes again. See section 4.5.5 in the
Haskell 98 Report. A pattern binding
29 May 2001 22:44:38 +0200, Ketil Malde [EMAIL PROTECTED] pisze:
Wouldn't
x f g
in a Forth'ish machine mean
g(f,x) -- using standard math notation, for a change
rather than
g(f(x))
?
It depends whether f changes the value at top of the stack or only
puts
Sun, 16 Sep 2001 10:52:07 -0400 (EDT), Mark Carroll [EMAIL PROTECTED] pisze:
To multiply apply a function, I'm currently using:
multiplyApply f n a = (iterate f a) !! n
...is there a Prelude function I've missed that already does this?
Unfortunately not.
Could I be doing this
02 Oct 2001 15:16:27 +0300, Dmitry Astapov [EMAIL PROTECTED] pisze:
I need to define SetsAsLists as an instance of Set by supplying
definitions for all Set methods, but definitions I wrote led me to
adding additional constraints on union and memeber methods.
What constraints? The class
05 Oct 2001 11:53:05 -0700, Carl R. Witty [EMAIL PROTECTED] pisze:
Data (T2 undefined) `seq` ()
*** Exception: Prelude.undefined
Data (T3 undefined) `seq` ()
*** Exception: Prelude.undefined
I can't think of a semantic difference between newtype and data
with a single unary strict
Sat, 20 Oct 2001 10:58:02 +0800 (GMT-8), Saswat Anand [EMAIL PROTECTED] pisze:
I am wondering why this function should not work with input [x,y]
(list with two elements) too, since third element is not referenced.
What a pattern matches is independent from which of the variables
it binds
27 Oct 2001 01:44:50 +0300, Dmitry Astapov [EMAIL PROTECTED] pisze:
well, ghc-5.02 seems to dislike something inside XmlLib.hs - it
could not find interface defs file for modules IOExts ..
Perhaps the option
-package lang
would help.
--
__( Marcin Kowalczyk * [EMAIL PROTECTED]
Sat, 29 Sep 2001 10:24:52 +0800 (GMT-8), Saswat Anand [EMAIL PROTECTED] pisze:
As regard to Marcin's suggestion of using a list of compact arrays,
although elements can be accessed faster, there will be a lot if
redundancy since windows are overlapping. So consecutive arrays
will contain
Thu, 27 Sep 2001 23:06:51 +0100, Jorge Adriano [EMAIL PROTECTED] pisze:
Seems to me like Hsk is not 'flushing' the output.
I guess this is right (sorry, haven't checked). You can flush in
two ways (using module IO):
1. At the beginning:
hSetBuffering stdout LineBuffering
or even
Fri, 28 Sep 2001 20:28:29 +0900, Dylan Thurston [EMAIL PROTECTED] pisze:
This sounds perfectly suited to Haskell's standard lazy lists. If you
only keep a pointer to the beginning of the data you need to work on,
then Haskell will automatically read in exactly as much data as you
use and GC
Sat, 6 Oct 2001 14:10:05 +0300, Cagdas Ozgenc [EMAIL PROTECTED] pisze:
As I understand from the concepts of Functional Programming, it is not
possible to implement a Hashtable ADT in Haskell language, where one can
insert, and access values in O(1) complexity. It has to be implemented
with
Sat, 1 Dec 2001 15:58:47 +, Jorge Adriano [EMAIL PROTECTED] pisze:
So my question is, is there anyway to force an argument to be reduced to
*normal form*?
The meaning of normal form (applied to an arbitrary Haskell type) is
not precisely defined. It depends on the type and must be
Fri, 7 Dec 2001 11:38:14 -0800, Mark P Jones [EMAIL PROTECTED] pisze:
There's no solid technical reason for this, but Haskell doesn't allow
it at the moment because there isn't an easy way to name an instance
declaration.
There is another problem: even if we created a syntax to name them,
if
Fri, 7 Dec 2001 17:12:52 -0500 (EST), David Feuer [EMAIL PROTECTED] pisze:
I'm wondering why Haskell doesn't support Scheme-like cond statements
or a pattern matching predicate.
I agree that both constructs make sense. The main objective is probably
that the syntax is already quite rich and
Tue, 15 Jan 2002 13:06:58 +0100, Rijk-Jan van Haaften [EMAIL PROTECTED] pisze:
This feature is one I consider among the worst in Haskell. If
a datatype with just a single constructor can be optimized away,
It can't. newtype has a different semantics than data, as others
explained. It would be
Thu, 21 Feb 2002 19:36:13 -0800, Ashley Yakeley [EMAIL PROTECTED] pisze:
data ContMonad p a = MkContMonad ((a - p) - p);
[...]
It's in GHC in module MonadCont, together with a monad transformer
providing continuations and some instances.
--
__( Marcin Kowalczyk * [EMAIL PROTECTED]
Fri, 6 Dec 2002 12:09:46 +0100, Ingo Wechsung [EMAIL PROTECTED] pisze:
No. My editor produces the ASCII code for horizontal tab, when I
hit the tab key. Just as it produces the ASCII code for a when I
hit the a key.
That's how it should be.
It shouln't, becase tabs are 8 spaces, which is
Dnia ro 16. lipca 2003 14:34, Ross Paterson napisa:
type R m = m - Maybe (R m, [m])
I don't think there's an extension of Haskell with regular type
unification. It's certainly possible, but there's an equivalent in
standard Haskell:
newtype R m = MkR (m - Maybe (R m, [m]))
It will
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 be faked as characters by (chr . fromIntegral).
The
Dnia ro 27. sierpnia 2003 20:48, Eugene Nonko napisa:
Are there any plans to extend Haskell parser to support prefix and
postfix operators? It will be just great for domain-specific languages.
It always kind of bothered me that unary minus is special.
Having only infix operators has the
W licie z czw, 02-10-2003, godz. 11:13, Juanma Barranquero pisze:
The intent is that Counted objects count the number of times an
operation is applied to them.
As you discovered, there is no meaningful count of operations. If an
operation doesn't do anything, do you count it? I suppose yes -
W licie z czw, 02-10-2003, godz. 12:59, Juanma Barranquero pisze:
It's not about counting the operations (that's just an example), but
accumulating any kind of state. For example:
data Accum a = Ac [a] a
instance Monad Accum where
return x = Ac [x] x
Ac _ x = f = let
W licie z czw, 02-10-2003, godz. 14:25, Juanma Barranquero pisze:
Yeah, I know. But it's difficult to ensure I'm satisfying the laws when
I'm not entirely sure what do they ask from me...
1. (return x) = f == f x
2. m = return == m
3. (m = f) = g == m = (\x - f x = g)
My intuition:
1 2.
W licie z pon, 27-10-2003, godz. 20:47, Christian Buschmann pisze:
Prelude Foreign.C castCCharToChar $ castCharToCChar ''
I would expect that this returns '', but it returns '\252'.
This is the same - instance Show Char displays non-ASCII characters
that way. You get the same effect if you
W licie z wto, 28-10-2003, godz. 12:30, Christian Buschmann pisze:
But what is the good reason that show is doing it that way? Wouldn't it
be better to output the '' as a '' instead of a code?
Then don't use show, output characters directly (putChar, putStr).
I thought that Char in Haskell
W licie z pon, 10-11-2003, godz. 16:41, David Roundy pisze:
I was wondering why System.Posix.Signals is as it is, and whether it could
be rewritten to use exceptions, which seems like the obvious way to handle
signals.
I don't understand. How to handle a signal using exceptions such that
the
W licie z czw, 13-11-2003, godz. 10:34, [EMAIL PROTECTED]
pisze:
If 'graphical' isn't taken too literally,
you can think of a dialog per function with the possibility to specify
pre and post conditions, tests, comments, etc.
I still doubt it would be more convenient. Maybe it's just me, but I
W licie z wto, 03-08-2004, godz. 13:05 +0200, Bjoern Knafla napisa:
Herb Sutter gave these rules :
An error is any failure that prevents a function from succeeding. Three
main kind of errors:
[...]
These kinds don't explain much. They don't give a clue which errors
to report by exceptions
Sven Panne [EMAIL PROTECTED] writes:
Hmmm, the Unicode tables start with ISO-Latin-1, so what would exactly break
when we stipulate that the standard encoding for string I/O in Haskell is
ISO-Latin-1? Additional encodings could be specified e.g. via a new open
variant.
That the encoding of
Glynn Clements [EMAIL PROTECTED] writes:
But the default encoding should
come from the locale instead of being ISO-8859-1.
The problem with that is that, if the locale's encoding is UTF-8, a
lot of stuff is going to break (i.e. anything in ISO-8859-* which
isn't limited to the 7-bit ASCII
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