On Mon, May 28, 2007 at 11:43:47AM +0100, Andrew Coppin wrote:
- Chapter 2 is... puzzling. Personally I've never seen the point of
trying to check a program against a specification. If you find a
mismatch then which thing is wrong - the program, or the spec?
Knowing that one of them is wrong
P.S. Have some cute code:
Control.Monad.Fix.fix ((1:) . scanl (+) 1)
Cute!
But what an un-cute qualified name:
:t Control.Monad.Fix.fix
Control.Monad.Fix.fix :: (a - a) - a
Has nothing to do with monads,
and would perhaps be considered as ``out of Control'' in any case...
;-)
kahl:
P.S. Have some cute code:
Control.Monad.Fix.fix ((1:) . scanl (+) 1)
Cute!
But what an un-cute qualified name:
:t Control.Monad.Fix.fix
Control.Monad.Fix.fix :: (a - a) - a
Has nothing to do with monads,
and would perhaps be considered as ``out of
At the risk of becoming repetitious, let's keep refining the Wiki to give these
competing proposals in their most up-to-date form. I'm not arguing against
email -- it's an excellent medium for discussion -- but having the outcomes
recorded makes them accessible to a much wider audience who
We got the names wrong!
data PLZ a = AWSUM_THX a | O_NOES String
instance Monad PLZ where
return= AWSUM_THX
fail = O_NOES
O_NOES s= _ = O_NOES s
AWSUM_THX x = f = f x
Thanks to mauke on #haskell.
-- Don
is that your implementation of LOLCODE?
:P
On 5/29/07, Donald Bruce Stewart [EMAIL PROTECTED] wrote:
We got the names wrong!
data PLZ a = AWSUM_THX a | O_NOES String
instance Monad PLZ where
return= AWSUM_THX
fail = O_NOES
O_NOES s
d.w.mead:
is that your implementation of LOLCODE?
:P
On 5/29/07, Donald Bruce Stewart [EMAIL PROTECTED]
wrote:
We got the names wrong!
data PLZ a = AWSUM_THX a | O_NOES String
instance Monad PLZ where
return= AWSUM_THX
from the letters of that word. A letter can be used at most as many
times as it appears in the input word. So, letter can only match
words with 0, 1, or 2 t's in them.
frequencies = map (\x - (head x, length x)) . group . sort
superset xs = \ys - let y = frequencies ys in
Donald Bruce Stewart wrote:
P.S. Have some cute code:
Control.Monad.Fix.fix ((1:) . scanl (+) 1)
this is cute indeed! (do you keep an emergency reserve of those around
for situations like this? ;-))
ever the interested amateur, i admittedly remain stumped by fix (there's
evidence i'm
On 29/05/07, Daniel McAllansmith [EMAIL PROTECTED] wrote:
Just in case there was some sort of miscommunication, the actual answer to
your question is (/=) :: a - a - Bool, as Neil said.
Almost, (/=) :: Eq a = a - a.
(Just for completeness.)
--
-David House, [EMAIL PROTECTED]
On Tue, May 29, 2007 at 11:20:27AM +0100, David House wrote:
Almost, (/=) :: Eq a = a - a.
Well, not quite :) You forgot - Bool at the end :)
(Just for completeness.)
Exactly :)
--
Antti-Juhani Kaijanaho, Jyväskylä
http://antti-juhani.kaijanaho.fi/newblog/
Hi Andrew!
I share your concerns about the simplicity of the language. Once
extensions exists, they are used widely, and readers of programs must
understand them, also if the extensions are used without need. I
understand the motivations for many type extensions, but library writers
tend to use
On 29/05/07, Antti-Juhani Kaijanaho [EMAIL PROTECTED] wrote:
Well, not quite :) You forgot - Bool at the end :)
Ha! Sorry, what a lovely ironic typo. :)
--
-David House, [EMAIL PROTECTED]
___
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
On Tue, May 29, 2007 at 11:20:27AM +0100, David House wrote:
On 29/05/07, Daniel McAllansmith [EMAIL PROTECTED] wrote:
Just in case there was some sort of miscommunication, the actual answer to
your question is (/=) :: a - a - Bool, as Neil said.
Almost, (/=) :: Eq a = a - a.
Almost again!
On Sun, 27 May 2007, Andrew Coppin wrote:
Personally, I try to avoid ever using list comprehensions.
Me too. Successfully, I have to add.
But every now and then I discover an expression which is apparently not
expressible without them - which is odd, considering they're only
sugar...
Hi Isaac
Why? If it's a binary package, the IO will return the compiled-in path,
which on the same distribution/whatever, should be the correct path. In
particular, on Windows, I assume that the IO returns something that is
in fact relative to the current position of the executable at the
At the risk of becoming repetitious, let's keep refining the Wiki to
give these competing proposals in their most up-to-date form. I'm not
arguing against email -- it's an excellent medium for discussion -- but
having the outcomes recorded makes them accessible to a much wider
audience who
On Sun, 27 May 2007, Andrew Coppin wrote:
such that a Reader is created with an initial list, and the read
function fetches 1 element out of that list. That is, the expression x
- read will take the head element of the list and put it into x,
keeping the tail to be read later.
(Oh yeah -
On Tue, May 29, 2007 at 12:15:23PM +0200, Vincent Kraeutler wrote:
Donald Bruce Stewart wrote:
P.S. Have some cute code:
Control.Monad.Fix.fix ((1:) . scanl (+) 1)
this is cute indeed! (do you keep an emergency reserve of those around
for situations like this? ;-))
ever the
G'day all.
Quoting Dan Mead [EMAIL PROTECTED]:
is that your implementation of LOLCODE?
O HAI IM IN UR CODE
REDUCIN' UR REDEKZEZ
BURNIN' UR MEGAHURTZ
Cheers,
Andrew Bromage
P.S. This is harder than writing l33t.
___
Hi,
It seems that if GHC is installed non-user-writable directory, and you want to
install a package in the home directory (using runghc Setup configure
--prefix=$HOME) this isn't possible: when running runghc Setup install you
get an error like this:
Unable to rename
On Tue, May 29, 2007 at 02:19:31PM +0200, Tomasz Zielonka wrote:
On Tue, May 29, 2007 at 12:15:23PM +0200, Vincent Kraeutler wrote:
ever the interested amateur, i admittedly remain stumped by fix (there's
evidence i'm not the only one [1])
The above code is equivalent to
let l = 1 :
Doug Kirk wrote:
No offense to the darcs creators, but
1) Only current Haskellers use it; everyone else either uses
Subversion or is migrating to it;
If that is true, then they have missed the point. DVC is a real win for
most workflows.
The applicable alternatives to darcs are : bzr,
Tomasz Zielonka wrote:
On Tue, May 29, 2007 at 02:19:31PM +0200, Tomasz Zielonka wrote:
On Tue, May 29, 2007 at 12:15:23PM +0200, Vincent Kraeutler wrote:
ever the interested amateur, i admittedly remain stumped by fix (there's
evidence i'm not the only one [1])
The above
On 29/05/07, Jules Bean [EMAIL PROTECTED] wrote:
Doug Kirk wrote:
No offense to the darcs creators, but
1) Only current Haskellers use it; everyone else either uses
Subversion or is migrating to it;
If that is true, then they have missed the point. DVC is a real win for
most workflows.
Vincent Kraeutler wrote:
Tomasz Zielonka wrote:
[snip]
anyhow. if someone has a pedestrian's guide to the fixed point
operator lying around, a link would be much appreciated.
i see that dons has very recently provided an answer for this on reddit:
vincent:
i see that the definition of fix (from Control.Monad.Fix) could not be
any simpler:
fix f = let x = f x in x
same goes for the type:
Prelude :t Control.Monad.Fix.fix
Control.Monad.Fix.fix :: (a - a) - a
it's just that i find it difficult to get concrete intellectual
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Grzegorz wrote:
Hi,
It seems that if GHC is installed non-user-writable directory, and you want to
install a package in the home directory (using runghc Setup configure
--prefix=$HOME) this isn't possible: when running runghc Setup install you
On 29/05/07, Vincent Kraeutler [EMAIL PROTECTED] wrote:
anyhow. if someone has a pedestrian's guide to the fixed point
operator lying around, a link would be much appreciated.
Here's a paraphrased quotation from Pierce's Types and Programming Languages:
Suppose we want to write a recursive
I've been playing with Text.Parsers.Frisby to see how it stacks against
other options and, while it's been great so far, I am finding that I
can't encode a grammar where what's acceptable depends on what's already
been parsed in some nontrivial way. To take a simple example, imagine a
grammar
Mirko Rahn wrote:
from the letters of that word. A letter can be used at most as many
times as it appears in the input word. So, letter can only match
words with 0, 1, or 2 t's in them.
frequencies = map (\x - (head x, length x)) . group . sort
superset xs = \ys - let y =
Actually, while I'm at it, another thing I was wondering:
Text.ParserCombinators.Parsec.Char offers us nice things like `lower'.
However, where's this stuff in Frisby? I could use something horrific
like oneOf [filter isLower [minBound .. maxBound ]] or something, but
how best to get
Vincent Kraeutler [EMAIL PROTECTED] writes:
anyhow. if someone has a pedestrian's guide to the fixed point
operator lying around, a link would be much appreciated.
At the risk of increasing rather than decreasing your
confusion (but in the hope that once you get over it you
will be
Isaac Dupree isaacdupree at charter.net writes:
You don't have permission to install it in a way that all users of that
GHC will then be able to use it. You should pass --user to runghc
Setup install for your desired effect. (whereas I shouldn't because my
GHC itself is also compiled by
Mark T.B. Carroll wrote:
I've been playing with Text.Parsers.Frisby to see how it stacks against
other options and, while it's been great so far, I am finding that I
can't encode a grammar where what's acceptable depends on what's already
been parsed in some nontrivial way.
[...]
Is this
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Vincent Kraeutler
anyhow. if someone has a pedestrian's guide to the fixed point
operator lying around, a link would be much appreciated.
Just to add to the noise... I've always quite liked Richard Gabriel's
The Why of Y
| I wish the compilers would allow more fine grained switches on languages
| extensions. -fglasgow-exts switches them all on, but in most cases I'm
| interested only in one. Then typing errors or design flaws (like 'type
| Synonym = Type', instead of wanted 'type Synonym a = Type a'; extended
|
apfelmus [EMAIL PROTECTED] writes:
(snip)
It's intentionally impossible. Frisby uses a dynamic programming
approach that crucially depends on the fact that the grammar in question
is context-free (actually something related, but the effect is the
same). You're trying to parse a
Mark T.B. Carroll wrote:
apfelmus [EMAIL PROTECTED] writes:
(snip)
This not a correct Pascal program, nevertheless the parse succeeds just
fine. The missing declaration for y will be detected when processing the
abstract syntax tree further. The key point is that the shape of the
abstract
[fixed some typos, mainly missing primes]
superset xs = superset' x . sort
where
x = sort xs
_ `superset'` [] = True
[] `superset'` _ = False
(x:xs) `superset'` (y:ys)
| x == y= xs `superset'` ys
| x y= xs `superset'` (y:ys)
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apfelmus wrote:
Mark T.B. Carroll wrote:
I've been playing with Text.Parsers.Frisby to see how it stacks against
other options and, while it's been great so far, I am finding that I
can't encode a grammar where what's acceptable depends on what's
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Simon Peyton-Jones wrote:
| I wish the compilers would allow more fine grained switches on languages
| extensions. -fglasgow-exts switches them all on, but in most cases I'm
| interested only in one. Then typing errors or design flaws (like 'type
(re-joining the list -- I forgot to reply all)
Vincent Kraeutler wrote:
Roberto Zunino wrote:
Vincent Kraeutler wrote:
i see that the definition of fix (from Control.Monad.Fix) could not be
any simpler:
fix f = let x = f x in x
I actually consider
fix f = f (fix f)
to be simpler. Alas,
Jules Bean wrote:
No offense to the darcs creators, but
1) Only current Haskellers use it; everyone else either uses
Subversion or is migrating to it;
If that is true, then they have missed the point. DVC is a real win for
most workflows.
We are indeed using darcs, so this discussion is a
On Tue, May 29, 2007 at 12:41:19PM -0400, Isaac Dupree wrote:
Simon Peyton-Jones wrote:
| I wish the compilers would allow more fine grained switches on languages
| extensions. -fglasgow-exts switches them all on, but in most cases I'm
| interested only in one. Then typing errors or design
I was wondering why, since IO is an instance of MonadFix [1], and
therefore of ArrowLoop (Kleisli m), and since The loop operator
expresses computations in which an output value is fed back as input,
even though the computation occurs only once. [2], the MonadFix or
ArrowLoop class (through
I didn't say there weren't others, simply that I didn't know of any
others (I don't just go looking for things online all the
time...having a real job really gets in the way of these things)! So I
wasn't really trying to disparage darcs. But here's another statistic:
OTOH, I work for companies, and they really value their assets,
especially software assets. So they *want* centralized stuff, so they
can ensure they have consistent backups (in the U.S.A. there is a lot
of regulation under Sarbanes-Oxley that requires this stuff). Right
now we're using
Claus Reinke wrote:
I'm thinking more about things like phantom types, rank-N
polymorphism, functional dependencies, GADTs, etc etc etc that nobody
actually understands.
this seems to be overly polymorphic in generalising over all types of
Haskell programmers, rather than admitting the
Nicolas Frisby wrote:
Your intended behavior for Reader indicates stateful computational
features. The read later roughly expands to be read by some monadic
action on the rhs of a = as in
(read = \x - read {-this is later-} = ...)
Recognizing the stateful nature gives you two options:
1)
Tomasz Zielonka wrote:
On Mon, May 28, 2007 at 11:43:47AM +0100, Andrew Coppin wrote:
- Chapter 2 is... puzzling. Personally I've never seen the point of
trying to check a program against a specification. If you find a
mismatch then which thing is wrong - the program, or the spec?
Donald Bruce Stewart wrote:
We got the names wrong!
data PLZ a = AWSUM_THX a | O_NOES String
instance Monad PLZ where
return= AWSUM_THX
fail = O_NOES
O_NOES s= _ = O_NOES s
AWSUM_THX x = f = f x
Thanks to mauke on #haskell.
Vincent Kraeutler wrote:
Donald Bruce Stewart wrote:
P.S. Have some cute code:
Control.Monad.Fix.fix ((1:) . scanl (+) 1)
this is cute indeed! (do you keep an emergency reserve of those around
for situations like this? ;-))
LOL! I bet he does as well...
I don't know. I
Henning Thielemann wrote:
On Sun, 27 May 2007, Andrew Coppin wrote:
Personally, I try to avoid ever using list comprehensions.
Me too. Successfully, I have to add.
But every now and then I discover an expression which is apparently not
expressible without them - which is odd,
On 5/29/07, Andrew Coppin [EMAIL PROTECTED] wrote:
My point is for most programs, trying to figure out exactly what you
want the program to do is going to be much harder than implementing a
program that does it.
Writing a spec can help with figuring out what you want your program to do.
Donald Bruce Stewart wrote:
I use it when I need a local loop expression, maybe once every couple of
months. A real world example from xmonad,
f = fix $ \again - do
more - checkMaskEvent d enterWindowMask ev
when more again
That is, keep sucking up X events till
Tim Chevalier wrote:
On 5/29/07, Andrew Coppin [EMAIL PROTECTED] wrote:
My point is for most programs, trying to figure out exactly what you
want the program to do is going to be much harder than implementing a
program that does it.
Writing a spec can help with figuring out what you want your
Andrew Coppin [EMAIL PROTECTED] writes:
OTOH, how many function can you write with :: [Int] - Int?
Quite a lot, but if you'd asked how many functions can you
write :: Integer - Integer, the answer would be all of
them (think about it).
--
Jón Fairbairn [EMAIL
Vincent Kraeutler wrote:
Donald Bruce Stewart wrote:
P.S. Have some cute code:
Control.Monad.Fix.fix ((1:) . scanl (+) 1)
either way, if one of the Masters Of The Shadow Y Style on this list
feels like throwing in another koan or two, you'll have at least one
thankful audience member
Isaac Dupree wrote:
apfelmus wrote:
Mark T.B. Carroll wrote:
I've been playing with Text.Parsers.Frisby to see how it stacks against
other options and, while it's been great so far, I am finding that I
can't encode a grammar where what's acceptable depends on what's already
been parsed in
I was wondering why, since IO is an instance of MonadFix [1], and
therefore of ArrowLoop (Kleisli m), and since The loop operator
expresses computations in which an output value is fed back as input,
even though the computation occurs only once. [2], the MonadFix or
ArrowLoop class (through
Gracjan Polak wrote:
Hi,
I stumbled at some interaction of Control.Monad.State.Strict, mdo and let I do
not understand. The following program:
{-# OPTIONS_GHC -fglasgow-exts #-}
module Main where
import Control.Monad.State.Strict
thenumber :: Float
thenumber = flip execState 1.3 $ mdo
c
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apfelmus wrote:
Isaac Dupree wrote:
apfelmus wrote:
Mark T.B. Carroll wrote:
I've been playing with Text.Parsers.Frisby to see how it stacks against
other options and, while it's been great so far, I am finding that I
can't encode a grammar
I've put aside the weekend of July 20-23 for the ICFP contest (http://
www.icfpcontest.org/), and am looking to form or join a haskell
wielding team. Any interest? Geographically I'm in Sydney, but have
entered in a previous year with a team of 3 from around the globe
which worked fine.
On Tue, 29 May 2007 19:28:02 -0400
Isaac Dupree [EMAIL PROTECTED] wrote:
Luckily, Haskell's laziness means that doing an extra postprocessing
pass doesn't necessarily yield two traversals requiring the whole
file to be stored in memory, nor worse hacks. (For grammars that
aren't too wild /
On 5/27/07, Ryan Ingram [EMAIL PROTECTED] wrote:
I was hoping that hSetBuffering would turn off the line buffering for stdin,
but it doesn't seem to work.
module Main where
import System.IO
main :: IO ()
main = do
hSetBuffering stdin NoBuffering
hSetBuffering stdout NoBuffering
On 5/28/07, Donald Bruce Stewart [EMAIL PROTECTED] wrote:
This thread should end, guys. It is inappropriate for the Haskell lists,
and appears to have been a simple misunderstanding anyway.
Thanks everyone. Please stay friendly!
-- Don
P.S. Have some cute code:
Control.Monad.Fix.fix
On 5/29/07, Doug Kirk [EMAIL PROTECTED] wrote:
OTOH, I work for companies, and they really value their assets,
especially software assets. So they *want* centralized stuff, so they
can ensure they have consistent backups (in the U.S.A. there is a lot
of regulation under Sarbanes-Oxley that
Hello,
Can anyone give me some tips concerning the following error:
myPrompt ghc --make -fffi f.hs -l mylib.lib
ghc --make -fffi f.hs -l mylib.lib
[1 of 1] Compiling Main ( f.hs, f.o )
Linking f.exe ...
d:\ghc\ghc6.6\gcc-lib\ld.exe: cannot find -l-Ld:/ghc/ghc6.6
On May 29, 2007, at 23:01 , jeff p wrote:
myPrompt ghc --make -fffi f.hs -l mylib.lib
For historical reasons, you can't have a space between the -l and the
library name. It's inserting an empty library name into the link
command, which is producing the odd cannot find error.
--
Hello,
On 5/29/07, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
On May 29, 2007, at 23:01 , jeff p wrote:
myPrompt ghc --make -fffi f.hs -l mylib.lib
For historical reasons, you can't have a space between the -l and the
library name. It's inserting an empty library name into the
On May 29, 2007, at 23:09 , jeff p wrote:
d:\ghc\ghc6.6\gcc-lib\ld.exe: cannot find -lmylib.lib
collect2: ld returned 1 exit status
which is strange because the file mylib.lib is in the same directory
as the haskell code.
Typically -l appends the necessary extension itself (.lib on
On Tue, May 29, 2007 at 11:09:15PM -0400, jeff p wrote:
Hello,
On 5/29/07, Brandon S. Allbery KF8NH [EMAIL PROTECTED] wrote:
On May 29, 2007, at 23:01 , jeff p wrote:
myPrompt ghc --make -fffi f.hs -l mylib.lib
For historical reasons, you can't have a space between the -l and the
On Tue, May 29, 2007 at 11:12:14PM -0400, Brandon S. Allbery KF8NH wrote:
It may be easier to see if ghc has an option to pass through the next
argument straight to the linker, or even recognizes .lib files and
-Wl,foobar
Stefan
___
Haskell-Cafe
Hello,
Thanks for the tips. I've gotten to the point where linking fails on
an undefined reference. The strange thing about this is that when I
make a C program to call the library function and compile with:
myPrompt gcc f.c mylib.lib
everything works fine. I think ghc is using it's own
On Tue, May 29, 2007 at 11:48:18PM -0400, jeff p wrote:
Hello,
Thanks for the tips. I've gotten to the point where linking fails on
an undefined reference. The strange thing about this is that when I
make a C program to call the library function and compile with:
myPrompt gcc f.c
Hello,
No, but ghc does pass a lot of funny flags...
Double check ccall v. stdcall in the import declaration. That bites a
lot of people on Windows.
My import statement originally looked like:
foreign import ccall mylib.h myFun my_fun :: CDouble - IO (Ptr CDouble)
and my original
True in principle. But if writing the spec is harder than writing
the actual program, all it means is you spend longer trying to
figure out how to express intuitively simple concepts using
advanced and very abstract and subtle predicate calculus.
As it turns out, Haskell sometimes makes a
On Wed, May 30, 2007 at 12:28:43AM -0400, jeff p wrote:
Hello,
No, but ghc does pass a lot of funny flags...
Double check ccall v. stdcall in the import declaration. That bites a
lot of people on Windows.
My import statement originally looked like:
foreign import ccall mylib.h
On Tue, 2007-05-29 at 14:05 -0500, Doug Kirk wrote:
I *want* people (and companies) to move to Haskell; therefore, I want
to lower the entry price. The goal is to introduce a new language,
not a new SCM tool. You certainly wouldn't want to leave the
impression that one MUST use darcs in order
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