| is not defined in the prelude but can be defined as
let (|) = flip ($)
to make it the opposite of $ which means the syntax looks more like the
Unix pipe '|' command
eg.
filter (\x- x 3 x 7) $ [1..10] ++ [5]
[1..10] ++ [5] | filter (\x- x 3 x 7)
res: [4,5,6]
note that with the |
Is it just me, or are all the regex implementations broken with
new change in lib layout for 6.8.1?
Are fixes available in darcs?
--
_jsn
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On Dec 4, 2007 1:28 AM, Don Stewart [EMAIL PROTECTED] wrote:
-- How to display results
instance Show Action where
show MoveOutOfBounds= Sorry you can't move in that direction.
show (MoveBadTerrain a) = case a of
Wall - You
On 04/12/2007, Felipe Lessa [EMAIL PROTECTED] wrote:
I always thought show was meant for returning a String that could be
used to recreate the original data if you copy-pasted it in your code
or if you used read (i.e. read . show == id). Reading the
documentation more carefully, I see that
I'd do something like
#if defined(__nhc98__) || defined(YHC)
#define NO_MONOMORPHISM_RESTRICTION
#endif
#ifdef NO_MONOMORPHISM_RESTRICTION
powers :: [[Integer]]
#endif
just to make it quite clear what's going on. (good comments would do just
as well).
Cheers,
Simon
Simon
Joel Reymont wrote:
Symptoms:
You build 6.8.1 from source on Leopard (x86 in my case) and then
junior:ghc-6.8.1 joelr$ ghci
GHCi, version 6.8.1: http://www.haskell.org/ghc/ :? for help
ghc-6.8.1:
/usr/local/lib/ghc-6.8.1/lib/base-3.0.0.0/HSbase-3.0.0.0.o: unknown
symbol `_environ'
Loading
On Dec 4, 2007 11:39 AM, Jules Bean [EMAIL PROTECTED] wrote:
Ben Franksen wrote:
I don't buy this. As has been noted by others before, IO is a very special
case, in that it can't be defined in Haskell itself, and there is no
evaluation function runIO :: IO a - a.
This is a straw man. Most
Ben Franksen wrote:
I don't buy this. As has been noted by others before, IO is a very special
case, in that it can't be defined in Haskell itself, and there is no
evaluation function runIO :: IO a - a.
This is a straw man. Most monads will not have such a function:
There is no function
Hi Gwern,
Shu-thing is great fun!
I think Monadius isn't compiling because most of the source files are
missing; you only have Main.hs in there.
Regards
Neil
On 4 Dec 2007, at 01:53, [EMAIL PROTECTED] wrote:
Hi everyone. With the permission of the authors, I'd like to
announce the
Ryan Ingram wrote:
On 12/3/07, Kalman Noel [EMAIL PROTECTED] wrote:
You're confusing sum and product types.
I'm not so sure; it looks like they already have that type (Exp) and wants
to use AlgExp to hold the folding functions used.
Ah, I didn't catch that on the first read. I suppose Carlo
On Tue, 4 Dec 2007, Dougal Stanton wrote:
On 04/12/2007, Felipe Lessa [EMAIL PROTECTED] wrote:
I always thought show was meant for returning a String that could be
used to recreate the original data if you copy-pasted it in your code
or if you used read (i.e. read . show == id). Reading
[redirecting to haskell-cafe]
Simon Peyton-Jones wrote:
But since the read may block, it matters *when* you perform it. For
example if you print Hello and then read the IVar, you'll block
after printing; but if you read the IVar and then print, the print
won't come out. If the operation was
On Tue, 2007-12-04 at 02:02 -0800, Jason Dusek wrote:
Is it just me, or are all the regex implementations broken with
new change in lib layout for 6.8.1?
Are fixes available in darcs?
Use these ones:
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/regex-base-0.72.0.1
Felipe Lessa wrote:
On Dec 4, 2007 1:28 AM, Don Stewart [EMAIL PROTECTED] wrote:
-- How to display results
instance Show Action where
show MoveOutOfBounds= Sorry you can't move in that direction.
show (MoveBadTerrain a) = case a of
Ask and ye shall receive. A simple guess-a-number game in MonadPrompt
follows.
But before I get to that, I have some comments:
Serializing the state at arbitrary places is hard; the Prompt contains a
continuation function so unless you have a way to serialize closures it
seems like you lose.
Hi... I give this error using hugs for the code:
---
f = foldl (\x y - add x y) 0 [1,2,3]
add x y = return (x + y)
---
I try:
f = foldl (\x y - counter x y) (return 0) [1,2,3]
but it dont solve, and
Hi,
Depending on what you want, you should either remove 'return' or change to
'foldM' (from Control.Monad). If you choose the latter, you also need to add a
type signature to f (because of the monomorphism restriction).
/ Emil
On 2007-12-04 14:43, Rafael wrote:
Hi... I give this error
Rafael skrev:
Hi... I give this error using hugs for the code:
---
f = foldl (\x y - add x y) 0 [1,2,3]
add x y = return (x + y)
---
I try:
f = foldl (\x y - counter x y) (return 0) [1,2,3]
but it
Andrew Coppin wrote:
Andrew Coppin wrote:
copy :: Word32 - IOUArray Word32 Bool - Word32 - IO (IOUArray
Word32 Bool)
copy p grid size = do
let size' = size * p
grid' - newArray (1,size') False
mapM_
(\n - do
b - readArray grid n
if b
then mapM_ (\x - writeArray grid' (n
Hello,
I want to quickcheck a property on a datatype representing
programs (=[Stmt]) and need to define a specific instance
instance Arbitrary [Stmt]
(mainly to restrict the size of the list).
In quickcheck an instance Arbitrary of lists is already defined.
Which parameters do I have to give
Hi Emil, I'm beginning in monad area...
I don't know about monomorphis restriction, but foldM works, a lot of thanks...
Matias tnks too, i'm conscious about return in the monadic chain.
thnks.
On Dec 4, 2007 12:00 PM, Emil Axelsson [EMAIL PROTECTED] wrote:
Hi,
Depending on what you
Stefan O'Rear wrote:
On Sun, Dec 02, 2007 at 05:45:48AM +0100, Tomasz Zielonka wrote:
On Fri, Nov 30, 2007 at 08:55:51AM +, Neil Mitchell wrote:
Hi
Prelude :b Control.Concurrent.MVar
module 'Control.Concurrent.MVar' is not interpreted
:b now defaults to :breakpoint, you want :browse
Steffen Mazanek wrote:
Hello,
I want to quickcheck a property on a datatype representing
programs (=[Stmt]) and need to define a specific instance
instance Arbitrary [Stmt]
(mainly to restrict the size of the list).
you don't always need to use instances. for example, I have (where
jules:
Felipe Lessa wrote:
On Dec 4, 2007 1:28 AM, Don Stewart [EMAIL PROTECTED] wrote:
-- How to display results
instance Show Action where
show MoveOutOfBounds= Sorry you can't move in that
direction.
show (MoveBadTerrain a) = case a of
Thank you!
I really appreciate your explanation, and I hope this will enable me
to do some interesting and usefull stuff, in addition to firming up my
understanding of some of the more advanced haskell type system
features.
MACID is a sort of RDBMS replacement used as a backend by the HAppS
web
hi
I am having trouble with a function that is supposed to eliminate spaces from
the start of a String and return the resulting string. I reckon a dropWhile
could be used but the isSpace bit is causing me problems...
words :: String - String
words a = case dropWhile isSpace a of
Brent Yorgey wrote:
One comment: it looks like (add exp1 exp2), (and exp1 exp2) and so on
above
are not correct. The second argument of foldExp is a value of type Exp,
so
you are pattern-matching on the constructors of Exp, and constructors are
always uppercase. Perhaps Exp has
Dan Piponi wrote:
Is there anything in any of the interfaces to Integer that will allow
me to quickly find the highest bit set in an Integer? If not, does
anyone have any recommendations for how to do it efficiently. There
are some obvious things that come to mind but which might involve
On Dec 4, 2007 12:13 PM, Ryan Bloor [EMAIL PROTECTED] wrote:
hi
I am having trouble with a function that is supposed to eliminate spaces
from the start of a String and return the resulting string. I reckon a
dropWhile could be used but the isSpace bit is causing me problems...
You need to
On Dec 4, 2007 9:21 AM, Steven Fodstad [EMAIL PROTECTED] wrote:
For the index, how about this:
truncate . (/(log 2)) . log . fromIntegral
That will not work. It will convert the Integer to Double, which will
overflow if the Integer is very large.
HI
I will try and explain it better.
I am meaning to write a function that takes a string, apple and
eliminates the spaces at the start ONLY. called removeSpace :: String
- String
I decided to use the function 'dropWhile' and another one 'isSpace' in the
'removeSpace'
On Dec 4, 2007 1:29 PM, Ryan Bloor [EMAIL PROTECTED] wrote:
HI
I will try and explain it better.
I am meaning to write a function that takes a string, apple and
eliminates the spaces at the start ONLY. called removeSpace ::
String - String
I decided to use the function
On 2007.12.04 12:12:04 +, Neil Bartlett [EMAIL PROTECTED] scribbled 2.2K
characters:
Hi Gwern,
Shu-thing is great fun!
I think Monadius isn't compiling because most of the source files are
missing; you only have Main.hs in there.
Regards
Neil
Oh - you're absolutely right. For some
look at the examples of dropWhile usage you got from the first result
when you get when you google on dropWhile.
t.
2007/12/4, Ryan Bloor [EMAIL PROTECTED]:
HI
I will try and explain it better.
I am meaning to write a function that takes a string, apple and
eliminates the spaces at
Hi
I'd do something like
#if defined(__nhc98__) || defined(YHC)
#define NO_MONOMORPHISM_RESTRICTION
#endif
#ifdef NO_MONOMORPHISM_RESTRICTION
powers :: [[Integer]]
#endif
just to make it quite clear what's going on. (good comments would do just
as well).
I'd rather avoid CPP, as
On Dec 3, 2007 10:05 PM, David Benbennick [EMAIL PROTECTED] wrote:
Could you please post your code here when you're done? I'd be
interested to see the final result.
This is just experimental code I'm playing with in order to implement
exact real arithmetic, so there'll never be a final result
On Dec 3, 2007 12:18 PM, Carlo Vivari [EMAIL PROTECTED] wrote:
Hi! I'm a begginer in haskell and I have a problem with an exercise, I
expect
someone could help me:
In one hand I have a declaration of an algebra data, like this:
data AlgExp a = AlgExp
{ litI :: Int - a,
litB :: Bool -
Yes,as I said before to other of you
the exp data type was also declared in the exercise (my fault not to say
it), and look as this:
data Exp = LitI Int
|LitB Bool
|Add Exp Exp
|And Exp Exp
|If Exp Exp Exp
--
View this message
dpiponi:
On Dec 3, 2007 10:05 PM, David Benbennick [EMAIL PROTECTED] wrote:
Could you please post your code here when you're done? I'd be
interested to see the final result.
This is just experimental code I'm playing with in order to implement
exact real arithmetic, so there'll never
A pure readIVar would be just like lazy I/O, with similar drawbacks.
With readIVar, the effect that lets you observe the evaluation order
is writeIVar; with hGetContents it is hClose. Conclusion: it's
probably no worse than lazy I/O.
Actually, it's considerably better.
+: implementation
Credit Suisse will be hosting a talk by Don Syme from Microsoft Research on
Monday December 10th. He will talk about F# and Microsoft's plans for it.
This talk is arranged by the New York Functional Programmers Network, a group
of individuals in the New York area who are interested in
Hi,
Getting same error in 2 diff. apps
* built with ghc-6.8.1.
* random-1.0.0.0 also built with 6.8.1
* random-1.0.0.0 is registered
# HAppS
-6.8.1/lib/random-1.0.0.0/HSrandom-1.0.0.0.o: unknown symbol
`oldzmtimezm1zi0zi0zi0_SystemziTime_a99_info'
ghc-6.8.1: unable to load package
Whatever the answer is, I expect it's relevant to Data.IntSet, which uses
big-endian patricia trees. - Conal
On Dec 3, 2007 8:36 PM, Dan Piponi [EMAIL PROTECTED] wrote:
Is there anything in any of the interfaces to Integer that will allow
me to quickly find the highest bit set in an Integer?
Hi
server text
| Just xs - parse text = let
x | field1 `elem` xs = error ... do one thing ...
| field2 `elem` xs = error ... do something else ...
in x
server _ = error ... invalid request ...
This now has the wrong semantics - before if parse text returned Just
[]
main = do
--irrelevant x - newIVar
let y = last [1..]
print test --was irrelevant writeIVar x 3
print y
Exactly. The termination concern doesn't seem to have to do with readIVar.
On Dec 4, 2007 11:56 AM, Isaac Dupree [EMAIL PROTECTED] wrote:
A pure readIVar would be
Hello all,
As you might have possibly read in some previous blog posts:
http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=10
http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=11
we (the FPSIG group) defined:
data BTree a = Leaf a
| Branch (BTree a) a (BTree a)
and a function that
On Dec 4, 2007 11:51 AM, Don Stewart [EMAIL PROTECTED] wrote:
Awesome. We can use this in Data.Bits, if you've got some QuickChecks
for it.
Hear hear. But is there any way to just make the compiler use
fastTestBit in place of testBit :: (Bits a) = a - Int - Bool when a
= Integer? (That is,
dbenbenn:
On Dec 4, 2007 11:51 AM, Don Stewart [EMAIL PROTECTED] wrote:
Awesome. We can use this in Data.Bits, if you've got some QuickChecks
for it.
Hear hear. But is there any way to just make the compiler use
fastTestBit in place of testBit :: (Bits a) = a - Int - Bool when a
=
On Tue, Dec 04, 2007 at 03:36:20PM +0100, Steffen Mazanek wrote:
Hello,
I want to quickcheck a property on a datatype representing
programs (=[Stmt]) and need to define a specific instance
instance Arbitrary [Stmt]
(mainly to restrict the size of the list).
In quickcheck an instance
Neil Mitchell wrote:
server text
| Just xs - parse text = let
x | field1 `elem` xs = error ... do one thing ...
| field2 `elem` xs = error ... do something else ...
in x
server _ = error ... invalid request ...
This now has the wrong semantics - before if parse
On Tue, Dec 04, 2007 at 05:13:19PM +, Ryan Bloor wrote:
hi
I am having trouble with a function that is supposed to eliminate spaces from
the start of a String and return the resulting string. I reckon a dropWhile
could be used but the isSpace bit is causing me problems...
words ::
Hi
findAllPath :: (a - Bool) - (BTree a) - [[a]]
findAllPath pred = g where
g (Leaf l) | pred l = [[l]]
g (Branch lf r rt) | pred r = map (r:) $ (findAllPath pred
lf) ++ (findAllPath pred rt)
g _ = []
without even using maybe. However, 2 questions
Neil Mitchell wrote:
is there any automated
way to know when a function is strict in its arguments?
Yes, strictness analysis is a very well studied subject -
...and is undecidable, in general. ;-)
Zun.
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On Tue, Dec 04, 2007 at 09:41:36PM +, Paulo J. Matos wrote:
Hello all,
As you might have possibly read in some previous blog posts:
http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=10
http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=11
we (the FPSIG group) defined:
data BTree a = Leaf a
Hello,
Which document discusses how to first build all dependencies and then
finally the target package? I prefer to read relevant documentation so I get
fully up to speed rather than take up bandwidth on this newsgroup asking
one question at a time.
Regards, Vasya
There's a bit of work required to make this code good enough for
general consumption, and I don't know much about Haskell internals.
(1) What is the official way to find the size of a word? A quick
look at 6.8.1's base/GHC/Num.lhs reveals that it uses a #defined
symbol.
(2) Is it safe to assume
Sterling Clover wrote:
Actually, I suspect GHC's strictness analyzer will give you reasonable
performance with even the naive version, but fancier ideas are at
http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog
If given an 'n' you are looking for the (2^x) such that 2^x = n
Hey everyone; recently I've been toying around with various methods of writing
a shell and reading the academic literature on such things. The best prior art
on the subject seems to be the ESTHER shell (see
http://citeseer.ist.psu.edu/689593.html,
http://citeseer.ist.psu.edu/744494.html,
Is there a reason why strictness is defined as
f _|_ = _|_
instead of, for example,
forall x :: Exception. f (throw x) = throw x
where an exception thrown from pure code is observable in IO.
In the second case we need to prove that the argument is evaluated at some
point, which is also
On Tue, Dec 04, 2007 at 03:07:01PM -0800, Ryan Ingram wrote:
Is there a reason why strictness is defined as
f _|_ = _|_
instead of, for example,
forall x :: Exception. f (throw x) = throw x
where an exception thrown from pure code is observable in IO.
In the second case we need to
On 12/4/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
Is there a reason why 2 + 2 is defined as 4 instead of, for example,
5?
Wow. That wasn't really necessary. 4 has a clear meaning (the number after
the number after the number after the number after zero) which is equivalent
to 2 + 2. I'm
I don't even understand what your notation means.
But apart from that, there are good reasons to define strictness
denotationally instead of operationally. Remember that _|_ is not only
exceptions, but also non-termination.
For instance, the following function is strict without using its
On Tue, Dec 04, 2007 at 03:35:28PM -0800, Ryan Ingram wrote:
On 12/4/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
Is there a reason why 2 + 2 is defined as 4 instead of, for example,
5?
Wow. That wasn't really necessary. 4 has a clear meaning (the number after
the number after the
On Tue, Dec 04, 2007 at 03:35:28PM -0800, Ryan Ingram wrote:
On 12/4/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
Well, one usually says something like f is strict in its 2nd argument
which on casual reading tends to make me think that it has something to do
with the argument. By the actual
On 2007-12-04, Paulo J. Matos [EMAIL PROTECTED] wrote:
Hello all,
As you might have possibly read in some previous blog posts:
http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=10
http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=11
we (the FPSIG group) defined:
data BTree a = Leaf a
It seems there is previous background here that I am unaware of. I'll
chime in anyway.
What you describe as the wrong semantics seems to me to be the more
appropriate. I am inferring that your expected behavior is explained
such that the first server match ought to fail (and fall through to
the
On 12/4/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
When you see an expression of the form:
f a
you generally want to evaluate a before applying; but if a is _|_, this
will only give the correct result if f a = _|_. Merely 'guaranteed to
evaluate' misses out on some common cases, for
Hello everyone,
Just to clarify, the intended semantics of my example was that it
should behave as if we were to duplicate the common prefix:
server text
| Just xs - parse text, field1 `elem` xs = ... do one thing ...
| Just xs - parse text, field2 `elem` xs = ... do something else ...
On Tue, Dec 04, 2007 at 07:43:36PM -0800, Ryan Ingram wrote:
On 12/4/07, Stefan O'Rear [EMAIL PROTECTED] wrote:
When you see an expression of the form:
f a
you generally want to evaluate a before applying; but if a is _|_, this
will only give the correct result if f a = _|_. Merely
http://code.enthought.com/enthon/ .. how do Haskell libraries/packages stack
up against this challenge?
Kind regards, Vasya
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Hello,
I believe that HUnit has absolutely not other package dependencies. When
I do a runhaskell Setup.hs build, I get the following error message: gcc:
installation problem, cannot
exec `cc1': No such file or directory. I am not sure what cc1 is? A
pass/phase of the gnu gcc compiler?
Kind
Is there an expert system implemented in Haskell, or a library perhaps?
A CLIPS/RETE implementation?
The main stumbling point, from my perspective, is how to implement a
knowledge base and check whether patterns with a certain shape have
been asserted. It's much easier to do this in a
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