Eric Stansifer wrote:
I am using a bunch of empty type classes to categorize some objects:
class FiniteSolidObject o
class FinitePatchObject o
class InfiniteSolidObject o
Since solid objects are exactly finite solid objects plus
infinite solid objects, there is an obvious way to code
PR Stanley wrote:
Paul: What is the underlying rationale for the Maybe data type?
It is the equivalent of a database field that can be NULL.
Paul: shock, horror! the null value or the absence of any value
denoted by null is not really in harmony with the relational model.
Patrick Surry [EMAIL PROTECTED] wrote:
Probably a silly question, but for me one of the nice things about
Haskell is that it's a lot like just writing math(s). But in contrast
to math you lose a lot of notational flexibility being limited to the
ascii character set in your source code.
Patrick Surry on 2008-05-14 09:43:44 -0400:
Probably a silly question, but for me one of the nice things about
Haskell is that it's a lot like just writing math(s). But in contrast
to math you lose a lot of notational flexibility being limited to the
ascii character set in your source code.
On Tue, 13 May 2008, Achim Schneider wrote:
Jed Brown [EMAIL PROTECTED] wrote:
It's not that simple with bits. They lack consistency just like the
usual US date format and the way Germans read numbers.
So you claim that you pronounce 14 tenty-four? In German pronunciation
is completely
Hi
It would be nice to be able to use a richer set of symbols in your source
code for operators and functions (e.g. integral, sum, dot and cross-product,
…), as well as variables (the standard upper and lower-case greek for
example, along with things like super- and sub-scripting,
Hi,
On Wed, May 14, 2008 at 03:59:58PM +0300, Lauri Alanko wrote:
On Wed, May 14, 2008 at 10:11:17AM +0100, Edsko de Vries wrote:
Suppose we have some data structure that uses HOAS; typically, a DSL
with explicit sharing. For example:
data Expr = One | Add Expr Expr | Let Expr (Expr -
On Wed, 14 May 2008, Patrick Surry wrote:
Probably a silly question, but for me one of the nice things about
Haskell is that it's a lot like just writing math(s). But in contrast
to math you lose a lot of notational flexibility being limited to the
ascii character set in your source code.
On Wed, May 14, 2008 at 03:59:23PM +0100, Edsko de Vries wrote:
You mention that a direct implementation of what I suggested would
break the monad laws, as (foo) and (Let foo id) are not equal. But one
might argue that they are in fact, in a sense, equivalent. Do you reckon
that if it is
Henning Thielemann [EMAIL PROTECTED] wrote:
On Tue, 13 May 2008, Achim Schneider wrote:
Jed Brown [EMAIL PROTECTED] wrote:
It's not that simple with bits. They lack consistency just like
the usual US date format and the way Germans read numbers.
So you claim that you pronounce
Newbie question: Given a list of type '[FilePath]', how do I create a list
of all those directories which do not actually exist, and then print the
list? I've figured out how to extract the ones which *do* exist, like so:
module Main where
import Control.Monad (filterM)
import System.Directory
On Wed, 14 May 2008, Mike Jarmy wrote:
Newbie question: Given a list of type '[FilePath]', how do I create a list
of all those directories which do not actually exist, and then print the
list? I've figured out how to extract the ones which *do* exist, like so:
module Main where
import
Am Mittwoch, 14. Mai 2008 17:47 schrieb Mike Jarmy:
Newbie question: Given a list of type '[FilePath]', how do I create a list
of all those directories which do not actually exist, and then print the
list? I've figured out how to extract the ones which *do* exist, like so:
module Main where
I share your perspective, Edsko. If foo and (Let foo id) are
indistinguishable to clients of your module and are equal with respect to
your intended semantics of Exp, then I'd say at least this one monad law
holds. - Conal
On Wed, May 14, 2008 at 7:59 AM, Edsko de Vries [EMAIL PROTECTED] wrote:
We've had a big debate over
mean xs = foldl' (+) 0 xs / fromIntegral (length xs)
For anyone who didn't follow it, the problem is that mean needs to
traverse its argument twice, so the entire list has to be held in
memory. So if xs = [1..10] then mean xs uses all your
memory, but
On Tue, May 13, 2008 at 9:06 PM, Ronald Guida [EMAIL PROTECTED] wrote:
I have a few questions about commutative monads and applicative functors.
From what I have read about applicative functors, they are weaker than
monads because with a monad, I can use the results of a computation to
David Menendez wrote:
To summarize: some applicative functors are commutative, some
applicative functors are monads, and the ones that are both are
commutative monads.
OK, so commutativity is orthogonal to idiom vs monad. Commutativity
depends on whether or not the order of side effects is
Don Stewart wrote:
ndmitchell:
2. Does anybody know how to actually read GHC's Core output anyway?
There is one different from standard Haskell I am aware of. In Core,
case x of _ - 1 will evaluate x, in Haskell it won't. Other than
that, its just Haskell, but without pattern
Neil Mitchell wrote:
Hi
1. What is ghc-core?
You actually answer this question as part of question 2. Think of it
as simple Haskell with some additional bits.
I rephrase: I know what GHC's Core language is. But Dons said I suggest
you install ghc-core, which suggests the
Brandon S. Allbery KF8NH wrote:
On 2008 May 13, at 17:01, Andrew Coppin wrote:
That definition of mean is wrong because it traverses the list twice.
(Curiosity: would traversing it twice in parallel work any better?)
As for the folds - I always *always* mix up
It might work better but
Brandon S. Allbery KF8NH wrote:
On 2008 May 13, at 17:12, Andrew Coppin wrote:
[Oh GOD I hope I didn't just start a Holy War...]
Er, I'd say it's already well in progress. :/
Oh dear.
Appologies to everybody who doesn't actually _care_ about which endian
mode their computer uses...
andrewcoppin:
Brandon S. Allbery KF8NH wrote:
On 2008 May 13, at 17:01, Andrew Coppin wrote:
That definition of mean is wrong because it traverses the list twice.
(Curiosity: would traversing it twice in parallel work any better?)
As for the folds - I always *always* mix up
Yes, using
Richard A. O'Keefe wrote:
On 14 May 2008, at 8:58 am, Andrew Coppin wrote:
What I'm trying to say [and saying very badly] is that Haskell is an
almost terrifyingly subtle language.
Name me a useful programming language that isn't.
Simply interchanging two for-loops, from
for (i = 0; i
On 2008 May 14, at 14:23, Andrew Coppin wrote:
Neil Mitchell wrote:
1. What is ghc-core?
You actually answer this question as part of question 2. Think of it
as simple Haskell with some additional bits.
I rephrase: I know what GHC's Core language is. But Dons said I
suggest you install
Henning Thielemann wrote:
On Tue, 13 May 2008, Achim Schneider wrote:
Jed Brown [EMAIL PROTECTED] wrote:
It's not that simple with bits. They lack consistency just like the
usual US date format and the way Germans read numbers.
So you claim that you pronounce 14 tenty-four? In German
On 2008 May 14, at 14:32, Andrew Coppin wrote:
Personally, I'd just like to be able to get rid of -, \ and
other such hacks. Would it be possible to amend GHC so that it
accepts - and [whatever the Unicode codepoint for left arrow
is] and treats both the same?
Both of those are already
On 2008 May 14, at 14:34, Dan Weston wrote:
So I've always wondered, if you are writing down a number being
dictated (slowly) by someone else, like 234, do you write the 2,
then leave space and write the 4, then go back and fill in with 3?
Or do you push the 4 onto the stack until the 3
Paul Johnson wrote:
The solution is for the programmer to rewrite mean to accumulate a
pair containing the running total and count together, then do the
division. This makes me wonder: could there be a compiler optimisation
rule for this, collapsing two iterations over a list into one.
Do
Reinier Lamers wrote:
Op 14-mei-2008, om 20:32 heeft Andrew Coppin het volgende geschreven:
Personally, I'd just like to be able to get rid of -, \ and
other such hacks. Would it be possible to amend GHC so that it
accepts - and [whatever the Unicode codepoint for left arrow is]
and treats
Albert Y. C. Lai wrote:
If you worry that the sum thread and the length thread are not
synchronized and therefore there is still no bound on the list prefix
kept in memory, I'm sure you can improve it by one of the chunking
strategies.
I'm more worried that data now has to go through tiny
On Wed, 14 May 2008, Dan Weston wrote:
Henning Thielemann wrote:
http://www.verein-zwanzigeins.de/
So I've always wondered, if you are writing down a number being dictated
(slowly) by someone else, like 234, do you write the 2, then leave space and
write the 4, then go back and fill in
On Wed, 14 May 2008, Brandon S. Allbery KF8NH wrote:
On 2008 May 14, at 14:34, Dan Weston wrote:
So I've always wondered, if you are writing down a number being dictated
(slowly) by someone else, like 234, do you write the 2, then leave space
and write the 4, then go back and fill in with
Brandon S. Allbery KF8NH wrote:
On 2008 May 14, at 14:32, Andrew Coppin wrote:
Personally, I'd just like to be able to get rid of -, \ and
other such hacks. Would it be possible to amend GHC so that it
accepts - and [whatever the Unicode codepoint for left arrow is]
and treats both the
On Wed, 14 May 2008, Andrew Coppin wrote:
Personally, I'd just like to be able to get rid of -, \ and other such
hacks. Would it be possible to amend GHC so that it accepts - and
[whatever the Unicode codepoint for left arrow is] and treats both the
same?
As said, the IDE Leksah can
Janis Voigtlaender wrote:
http://wwwtcs.inf.tu-dresden.de/~voigt/mpc08.pdf
It is well-known that trees with substitution form a monad.
...OK, I just learned something new. Hanging around Haskell Cafe can be
so illuminating! :-)
Now, if only I could actually comprehend the rest of the
Henning Thielemann wrote:
On Wed, 14 May 2008, Andrew Coppin wrote:
Personally, I'd just like to be able to get rid of -, \ and
other such hacks. Would it be possible to amend GHC so that it
accepts - and [whatever the Unicode codepoint for left arrow is]
and treats both the same?
As
Hi
Bjorn Bringert wrote:
Mads: Preparing the statement and asking the DB about the type at
compile is a great idea! I've never thought of that. Please consider
completing this and packaging it as a library.
Thanks for the nice remark. And I will begin completing the idea, as
soon I have
On 2008 May 14, at 15:00, Andrew Coppin wrote:
Brandon S. Allbery KF8NH wrote:
On 2008 May 14, at 14:32, Andrew Coppin wrote:
Personally, I'd just like to be able to get rid of -, \ and
other such hacks. Would it be possible to amend GHC so that it
accepts - and [whatever the Unicode
Andrew Coppin wrote:
Henning Thielemann wrote:
As said, the IDE Leksah can display code exactly like this ...
I noticed the first time. Clearly this is another toy I'm going to
have to try out sometime...
...and then he discovers that Darcs isn't working any more. :-(
I've recently
On 2008 May 14, at 15:00, Andrew Coppin wrote:
Brandon S. Allbery KF8NH wrote:
On 2008 May 14, at 14:32, Andrew Coppin wrote:
Personally, I'd just like to be able to get rid of -, \ and
other such hacks. Would it be possible to amend GHC so that it
accepts - and [whatever the Unicode
On Wed, May 14, 2008 at 12:03 PM, Andrew Coppin
[EMAIL PROTECTED] wrote:
It is well-known that trees with substitution form a monad.
Now that's funny. Compare with the first line of this paper:
http://citeseer.ist.psu.edu/510658.html
Anyway, I worked through an elementary example of this with
On Wed, May 14, 2008 at 08:37:53PM +0100, Andrew Coppin wrote:
Andrew Coppin wrote:
Henning Thielemann wrote:
As said, the IDE Leksah can display code exactly like this ...
I noticed the first time. Clearly this is another toy I'm going to
have to try out sometime...
...and then he
David Roundy wrote:
On Wed, May 14, 2008 at 08:37:53PM +0100, Andrew Coppin wrote:
Andrew Coppin wrote:
I've recently reinstalled Windows, so I decided to go download the
latest Darcs and set that up. Now it's complaining that I don't have
curl or wget. (Never used to do that before.)
Hello Andrew,
Thursday, May 15, 2008, 12:49:32 AM, you wrote:
touch. Now, let's see what this IDE actually looks li-- oh you have GOT
to be KIDDING me! It can't find the right GTK DLL?!?
gtk2hs includes *developer* gtk2 environment. while it should work
fine (as far as it's in your path), you
Henning Thielemann [EMAIL PROTECTED] wrote:
Of course, we write down 243, realize the mistake and rewrite the
number. :-) Actually, many pupils have problems with the mixed order
of digits and give solutions like this one in examinations:
8 * 8 = 46
because they write the digits as they
It's not that simple with bits. They lack consistency just like the
usual US date format and the way Germans read numbers.
So you claim that you pronounce 14 tenty-four? In German pronunciation
is completely uniform from 13 to 99.
http://www.verein-zwanzigeins.de/
So I've always wondered,
Hello Olivier,
Thursday, May 15, 2008, 1:26:28 AM, you wrote:
RFC_RC _stdcall RfcUTF8ToSAPUC(const RFC_BYTE *utf8, unsigned
utf8Length, SAP_UC *sapuc,
unsigned *sapucSize, unsigned *resultLength, RFC_ERROR_INFO *info)
foreign import ccall unsafe sapnwrfc.h RfcUTF8ToSAPUC
Feel free to CC me or the ticket with things like that. I'll be
working on this for this year's GSoC and it'd be helpful to find out
what I should tackle first.
Hi Thomas,
thanks, I was wondering about your project. Is there a project
page documenting the issues/tickets you look at, and
I have read that Monad is stronger than Idiom because Monad lets me
use the results of a computation to choose between the side effects of
alternative future computations, while Idiom does not have this
feature. Arrow does not have this feature either.
ArrowChoice has the feature that the sum
Conal Elliott [EMAIL PROTECTED] wrote in article [EMAIL PROTECTED] in
gmane.comp.lang.haskell.cafe:
I share your perspective, Edsko. If foo and (Let foo id) are
indistinguishable to clients of your module and are equal with respect to
your intended semantics of Exp, then I'd say at least this
On Wed, May 14, 2008 at 5:46 PM, Bulat Ziganshin [EMAIL PROTECTED]
wrote:
use stdcall instead of ccall in Haskell too. afair, depending on
calling conventions, different prefixes/suffixes are used when
translating C function name into assembler (dll) name
Oops, sorry I copied the wrong line
On Wed, 2008-05-14 at 12:42 -0700, Dan Piponi wrote:
On Wed, May 14, 2008 at 12:03 PM, Andrew Coppin
[EMAIL PROTECTED] wrote:
It is well-known that trees with substitution form a monad.
Now that's funny. Compare with the first line of this paper:
http://citeseer.ist.psu.edu/510658.html
Ronald Guida wrote:
I have read that Monad is stronger than Idiom because Monad lets me
use the results of a computation to choose between the side effects of
alternative future computations, while Idiom does not have this
feature. Arrow does not have this feature either.
ArrowChoice has the
2008/5/15 Claus Reinke [EMAIL PROTECTED]:
Feel free to CC me or the ticket with things like that. I'll be
IMHO, trying to support a semantics- and comment-preserving
roundtrip in (pretty . parse) would be a good way to start (David
says he's going to look at the extracting
On Mon, 2008-05-12 at 19:30 -0700, Don Stewart wrote:
I offer up the following example:
mean xs = sum xs / length xs
Now try, say, mean [1.. 1e9], and watch GHC eat several GB of RAM. (!!)
But you know why, don't you?
sat down and spent the best part of a day writing an MD5
derek.a.elkins:
On Mon, 2008-05-12 at 19:30 -0700, Don Stewart wrote:
I offer up the following example:
mean xs = sum xs / length xs
Now try, say, mean [1.. 1e9], and watch GHC eat several GB of RAM. (!!)
But you know why, don't you?
sat down and spent the best part of
On 14 May 2008, at 2:13 PM, Claus Reinke wrote:
It's not that simple with bits. They lack consistency just
like the
usual US date format and the way Germans read numbers.
So you claim that you pronounce 14 tenty-four? In German
pronunciation
is completely uniform from 13 to 99.
So I've always wondered, if you are writing down a number being dictated
(slowly) by someone else, like 234, do you write the 2, then leave space and
write the 4, then go back and fill in with 3? Or do you push the 4 onto the
stack until the 3 arrives, and write 34 at once.
My German
On 15 May 2008, at 7:19 am, Brandon S. Allbery KF8NH wrote:
Unfortunately, while I thought there was a distinct lambda sign that
wasn't the lowercase Greek letter, there isn't. (That said, I don't
see why it couldn't be a keyword. You'd need a space after it.)
There are three lambda
Richard A. O'Keefe wrote:
At least to give editors a fighting chance of matching their concept of a
word with Haskell tokens, it might be better to use nabla instead of
lambda. Other old APL fans may understand why (:-). Alternatively, didn't
Church really want to use a character rather like a
Lots of folk have suggested writing code with Unicode symbols, but that
doesn't really get me where I'm thinking of. Back in the day, I spent
many happy hours writing math(s) in amstex style, peppered with latex
backslash references/macros for greek symbols, set operators as well as
character
Sorry, missed a mail digest: LyX and lhs2tex sound more like what I
mean.
Patrick
-Original Message-
From: Patrick Surry
Sent: Wednesday, May 14, 2008 10:24 PM
To: 'haskell-cafe@haskell.org'
Subject: Re: Richer (than ascii) notation for haskell source?
Lots of folk have suggested
On 2008 May 14, at 22:07, Richard A. O'Keefe wrote:
On 15 May 2008, at 7:19 am, Brandon S. Allbery KF8NH wrote:
Unfortunately, while I thought there was a distinct lambda sign
that wasn't the lowercase Greek letter, there isn't. (That said, I
don't see why it couldn't be a keyword. You'd
On 2008 May 14, at 22:23, Patrick Surry wrote:
So maybe what I really want is to essentially write my source in
(la)tex
and be able to both compile and render to dvi at the same time? I
suppose word's crazy equation editor or mathml is another option but
it
makes the source itself either
On 15 May 2008, at 2:34 pm, Brandon S. Allbery KF8NH wrote:
Hm. Newer Unicode standard than the version supported by OSX and
GNOME, I take it? That's not so helpful if nobody actually supports
the characters in question. (My Mac claims 166CC is in an
unassigned area, and no supplied
On 2008 May 14, at 22:40, Richard A. O'Keefe wrote:
I still suspect it would not be outside the pale to make λ a
keyword. We already have several, after all.
I'd rather not have to write \x as λ x with a space required after
the λ.
I suspect that λ is the lambda-symbol iff it is not
On Thu, 2008-05-15 at 14:40 +1200, Richard A. O'Keefe wrote:
On 15 May 2008, at 2:34 pm, Brandon S. Allbery KF8NH wrote:
Hm. Newer Unicode standard than the version supported by OSX and
GNOME, I take it? That's not so helpful if nobody actually supports
the characters in question.
Claus Reinke wrote:
Germans have no problems with sentences which though started at
the beginning when observed closely and in the light of day (none of
which adds anything to the content of the sentence in which the very
parenthetical remark you -dear reader- are reading at this very moment
On 2008 May 14, at 22:57, Derek Elkins wrote:
On Thu, 2008-05-15 at 14:40 +1200, Richard A. O'Keefe wrote:
I suspect that λ is the lambda-symbol iff it is not preceded by any
identifier character and is not followed by a Greek letter might
work.
λω. ...
λα. ...
λδ ε. ...
Come to think
On Wed, 2008-05-14 at 20:59 +0200, Henning Thielemann wrote:
. . .
Interesting to know what jokes are told about Germans. 8-] So, do English
professors save their prepositions for the end of a lecture?
This seems peculiarly apropos:
I lately lost a preposition.
It hid, I thought,
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