Re: [Haskell-cafe] Linker problems linking FFI import call in Windows
On Tue, Jul 15, 2008 at 11:51 PM, PJ Durai [EMAIL PROTECTED] wrote: I am trying to import some functions from a windows DLL. I am getting strange errors. (This used to work with previous versions of GHC. 6.6 I think.). You may have to create an import library for the DLL. I had a similar problem and solved it that way. Look at http://www.emmestech.com/moron_guides/moron1.html for advices on how to create such a library. My problem was that the exports in the dll were prefixed with an underscore. I had to remove them from the .def file before creating the import library. Best regards, Olivier. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] CAL (OpenQuark) and enterprise
Nice:) Daniil Elovkov wrote: fero wrote: And what if writing new application? Has anybody experience with enterprise application in functional language? Is it really clearer? I can see a advantage in using Scala but it doesn't have some features from Haskell or CAL or requires more code to write. Or better has anybody experience with the same and functional language for JVM? And what about ORM (e.g. Hibernate)? And what about objects, they are stateful itself. And CRUD is a very common part of enterprise applications and I think it's easier in imperative style (client is declarative of course but it assigns values to fields). I am interested in ours opinions/experience in business logic (not any infrastructure or client stuff) for apps such as accounting/bank/insurance/document management... systems in functional languages. Sometimes the rules for these kind of apps is more complex that it seem to be and such systems are maintained for many years (some even decades) so it needs to be readable. Rule engines are very popularized among java community now but I think many logic can be expressed clearer in functions. It is maybe useful for some kind of logic (e.g. calculate price with discounts) but for what I do I can write the same clearer in java that in rule engine (and much clearer in Haskell and I am only beginner. What will come after few years coding;). You may start writing more obscure code. Look at this: http://www.willamette.edu/~fruehr/haskell/evolution.html This is humour, of course. Miles Sabin wrote: On Wed, Jul 9, 2008 at 6:28 PM, Neil Mitchell [EMAIL PROTECTED] wrote: On the Haskell list I think its fair to say everyone recommends you should use Haskell. Not necessarily. If the OP has a significant body of existing Java code (s)he has to work with (which is what the question suggests) then Scala would most likely be a very good place to look. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- View this message in context: http://www.nabble.com/CAL-%28OpenQuark%29-and-enterprise-tp18366397p18483627.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Mutually recursive modules and google protocol-buffers
Thanks Roberto!
Roberto Zunino wrote:
Chris Kuklewicz wrote:
There is no way to create a A.hs-boot file that has all of
(1) Allows A.hs-boot to be compiled without compiling B.hs first
(2) Allows B.hs (with a {-# SOURCE #-} pragma) to be compiled after
A.hs-boot
(3) Allows A.hs to compiled after A.hs-boot with a consistent interface
I thought the following A.hs-boot would suffice:
module A(A) where
data A
There's no need to provide the data constructors for type A. Does this
violate any of the goals above?
Regards,
Zun.
I tried that experiment. The failure is complicated, and triggers be a ghc bug.
Hmmm... the bug for
module A(A) where
data A
deriving Show
using ghc -c -XGeneralizedNewtypeDeriving A.hs-boot is
A.hs-boot:2:0:ghc-6.8.3: panic! (the 'impossible' happened)
(GHC version 6.8.3 for powerpc-apple-darwin):
newTyConEtadRhs main:A.A{tc r5z}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Is this a known bug?
But now I see that
module A(A(..)) where
import B(B)
data A = A B | End
deriving Show
does work. And avoids the bug!
--
Chris
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[Haskell-cafe] Re: Euler 201 performance mystery
[EMAIL PROTECTED] wrote:
Dear Group,
I've spend the last few days figuring out the solution to Euler Problem 201 in
haskell. I first tried a relatively elegant approach based on Data.Map but
the performance was horrible. I never actually arrived at the answer. I then
rewrote the same algorithm using STUArrays and it was lightning. I have
posted both versions of the code at:
http://www.maztravel.com/haskell/euler_problem_201.html
and would appreciate any insights that you master haskellers can provide on
why the speed difference is so huge. Thanks in advance.
Henry Laxen
First, you may want to change the map type to
type SumMap = Map (Int,Int) Int
since you're working with pairs (length, sum), not lists. I mean, you're doing
the same with STUArray (Int,Int) Int .
Did you try to estimate the running time of both data structures? Calculating
the number of big-O operations on the back of an envelope is a very good
guideline. So, Data.Map.insert takes O(log (size of map)) operations and so
on. A rule of thumb is that a computer can perform 10 million operations per
second (maybe 100, that was five years ago :)). Granted, this rule works best
for C programs whereas Haskell is quite sensitive to constant factors, in
particular concerning memory and cache effects. So, the rule is pretty accurate
for an STUArray but you may have to multiply with 10 to get the right order of
magnitude for Data.Map.
As you have noted, the choice of data structure (Map, STUArray, something else)
is important (Map only touches existing sums, but STUArray has O(1) access and
uses a tight representation in memory). But in the following, I want to discuss
something what you did implicitly, namely how to *calculate* the general
algorithm in a mechanical fashion. This follows the lines of Richard Bird's
work, of which the book Algebra of Programming
http://web.comlab.ox.ac.uk/oucl/research/pdt/ap/pubs.html#Bird-deMoor96:Algebra
is one of the cornerstones. The systematic derivation of dynamic programming
algorithms has been rediscovered in a more direct but less general fashion in
http://bibiserv.techfak.uni-bielefeld.de/adp/
Euler problem 201 asks to calculate the possible sums you can form with 50
elements from the set of square numbers from 1^2 to 100^2. Hence, given a function
subsets [] = [[]]
subsets (x:xs) = map (x:) (subsets xs) ++ subsets xs
that returns all subsets of a set, we can implement a solution as follows:
squares = map (^2) [1..100]
euler201 = map sum . filter ((==50) . length) . subsets $ squares
While hopelessly inefficient, this solution is obviously correct! In fact, we
did barely more than write down the task.
Ok ok, the solution is *not correct* because map sum may generate
*duplicates*. In other words, subsets generates a lot of sets that have the
same sum. But that's the key point for creating a better algorithm: we could be
a lot faster if merging subsets with the same sum and generating these subsets
could be interleaved.
To that end, we first have to move the length filter to after the summation:
map sum . filter ((==50) . length)
= map snd . filter ((==50) . fst) . map (length sum)
The function () is very useful and defined as
(length sum) xs = (length xs, sum xs)
You can import (a generalization of) of it from Control.Arrow. In other words,
our solution now reads
euler201 = map snd . filter ((==50) . fst) . subsums $ squares
where
subsums = map (length sum) . subsets
and our task is to find a definition of subsums that fuses summation and
subset generation.
But this is a straightforward calculation! Let's assume that we have an
implementation of Sets that we can use for merging duplicates. In other words,
we assume operations
singleton :: a - Set a
union :: Set a - Set a - Set a
map :: (a - b) - Set a - Set b
so that subsets becomes
subsets [] = singleton []
subsets (x:xs) = map (x:) (subsets xs) `union` subsets xs
Now, let's calculate:
subsums []
= { definition }
map (length sum) (subsets [])
= { subsets }
map (length sum) (singleton [])
= { map }
singleton ((length sum) [])
= { length sum }
singleton (0,0)
subsums (x:xs)
= { definition }
map (length sum) (subsets (x:xs))
= { subsets }
map (length sum) (map (x:) (subsets xs) `union` subsets xs)
= { map preserves unions }
map (length sum) (map (x:) subsets xs)
`union` map (length sum) (subsets xs)
= { map fusion }
map (length sum . (x:)) (subsets xs)
`union` map (length sum)(subsets xs)
= { move (length sum) to the front, see footnote }
map ((\(n,s) - (n+1,s+x)) . (length sum)) (subsets xs)
`union` map (length sum) (subsets xs)
= { reverse map fusion }
map (\(n,s) - (n+1,s+x)) (map (length sum) (subsets xs))
`union` map (length sum) (subsets xs)
= {
RE: [Haskell-cafe] Mutually recursive modules and google protocol-buffers
Hi, module A(A) where data A deriving Show I think you should use instance Show A rather than deriving Show. All the boot file needs to do is say that the instance exists, not explain how it is constructed. Cheers, Ganesh == Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html == ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Strange space leak
Grzegorz Chrupala wrote: split DOC . words . map toLower = (:[]) . words . map toLower Since you converted everything to lowercase, the string DOC will never appear in the text, resulting in a single huge document. Oops, that should have been obvious, sorry for the dumb question. Thanks, No problem, it was not obvious to me and I had fun trying to figure it out :) Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] win32: haddock: internal Haddock or GHC error?
Using GHC 6.8.2 and haddock 2.0.0.0. in WinXP (SP3) I am trying to follow instructions from How to write a Haskell programhttp://www.haskell.org/haskellwiki/How_to_write_a_Haskell_program#Build_some_haddock_documentation . Everything goes well, until I try to generate html documentation for the project. Then I get the following errors: C:\wks\haqrunhaskell Setup.lhs haddock --executables Preprocessing executables for haq-0.0... Running Haddock for haq-0.0... Preprocessing executables for haq-0.0... Warning: Cannot read C:/usr/ghc-6.8.2/doc/libraries/base\base.haddock: Magic number mismatch: couldn't load interface file: C:/usr/ghc-6.8.2/doc/li braries/base\\base.haddock Skipping this interface. Warning: main:Main: could not find link destinations for: GHC.IOBase.IO haddock: internal Haddock or GHC error: c:/builds/haddock-2/install\haddock-2.0. 0.0/html/haddock.css: openFile: does not exist (No such file or directory) Any ideas how to solve this? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] win32: haddock: internal Haddock or GHC error?
Hi Dmitri, How did you obtain Haddock 2.0? Did you download it off hackage and install it, using the standard cabal bits? Can you also do runhaskell Setup configure -v, so we can see which Haddock Cabal is attempting to use. Thanks Neil C:\wks\haqrunhaskell Setup.lhs haddock --executables Preprocessing executables for haq-0.0... Running Haddock for haq-0.0... Preprocessing executables for haq-0.0... Warning: Cannot read C:/usr/ghc-6.8.2/doc/libraries/base\base.haddock: Magic number mismatch: couldn't load interface file: C:/usr/ghc-6.8.2/doc/li braries/base\\base.haddock Skipping this interface. Warning: main:Main: could not find link destinations for: GHC.IOBase.IO haddock: internal Haddock or GHC error: c:/builds/haddock-2/install\haddock-2.0. 0.0/html/haddock.css: openFile: does not exist (No such file or directory) Any ideas how to solve this? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] win32: haddock: internal Haddock or GHC error?
Neil, Thanks for the quick response! I got haddock from its site ( http://haskell.org/haddock/#Download )using the link that says: Windows: a binary distribution http://haskell.org/haddock/dist/haddock-2.0.0.0-Win32.zip is available, just unzip and go. My configuration: C:\wks\haqrunhaskell Setup.lhs configure -v Configuring haq-0.0... Dependency base-any: using base-3.0.1.0 Using compiler: ghc-6.8.2 Using install prefix: C:\Program Files\Haskell Binaries installed in: C:\Program Files\Haskell\bin Libraries installed in: C:\Program Files\Haskell\haq-0.0\ghc-6.8.2 Private binaries installed in: C:\Program Files\Haskell\haq-0.0 Data files installed in: C:\Program Files\Haskell\haq-0.0 Documentation installed in: C:\Program Files\Haskell\doc\haq-0.0 No alex found Using ar found on system at: C:\usr\ghc-6.8.2\bin\ar.exe No c2hs found No cpphs found No ffihugs found Using ghc version 6.8.2 found on system at: C:\usr\ghc-6.8.2\bin\ghc.exe Using ghc-pkg version 6.8.2 found on system at: C:\usr\ghc-6.8.2\bin\ghc-pkg.exe No greencard found Using haddock version 2.0.0.0 found on system at: C:\usr\haddock\haddock.exe No happy found No hmake found Using hsc2hs version 0.66-ghc found on system at: C:\usr\ghc-6.8.2\bin\hsc2hs.ex e No hscolour found No hugs found No jhc found Using ld found on system at: C:\usr\ghc-6.8.2\gcc-lib\ld.exe No nhc98 found No pfesetup found No pkg-config found No ranlib found No tar found On Wed, Jul 16, 2008 at 4:45 PM, Neil Mitchell [EMAIL PROTECTED] wrote: Hi Dmitri, How did you obtain Haddock 2.0? Did you download it off hackage and install it, using the standard cabal bits? Can you also do runhaskell Setup configure -v, so we can see which Haddock Cabal is attempting to use. Thanks Neil C:\wks\haqrunhaskell Setup.lhs haddock --executables Preprocessing executables for haq-0.0... Running Haddock for haq-0.0... Preprocessing executables for haq-0.0... Warning: Cannot read C:/usr/ghc-6.8.2/doc/libraries/base\base.haddock: Magic number mismatch: couldn't load interface file: C:/usr/ghc-6.8.2/doc/li braries/base\\base.haddock Skipping this interface. Warning: main:Main: could not find link destinations for: GHC.IOBase.IO haddock: internal Haddock or GHC error: c:/builds/haddock-2/install\haddock-2.0. 0.0/html/haddock.css: openFile: does not exist (No such file or directory) Any ideas how to solve this? Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Dmitri O. Kondratiev [EMAIL PROTECTED] http://www.geocities.com/dkondr ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Strange space leak
apfelmus wrote: Grzegorz Chrupala wrote: split DOC . words . map toLower = (:[]) . words . map toLower Since you converted everything to lowercase, the string DOC will never appear in the text, resulting in a single huge document. Oops, that should have been obvious, sorry for the dumb question. Thanks, No problem, it was not obvious to me and I had fun trying to figure it out :) Speaking of not obvious: Haskell's type system catches a lot of bugs -- but still gives no help with this particular 'problem'. But one can easily imagine an extension to a type system which could have detected that DOC can never occur in the result of words . map toLower, and then with a bit more work [type-level Nat], the type of the full expression could have encoded that the result is always going to be of length 1. That would surely have been a good hint that something non-trivial was going on. Whether a Haskell-friendly type system extension could be created/implemented which would cover this example, I don't know. However, I have had a lot of fun with the underlying idea: anytime someone encounters a bug in their code (and relates the debugging story on haskell-cafe), try to imagine how the type system could be extended to automate that. In most cases, I don't mean to have the type system reject the code, but rather to have an inferred type that would make it obvious that the code did not behave as expected. Jacques ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Euler 201 performance mystery
apfelmus wrote: In other words, we have now calculated the more efficient program euler201 = map snd . filter ((==50) . fst) . subsums $ squares where subsums [] = singleton (0,0) subsums (x:xs) = map (\(n,s) - (n+1,s+x)) (subsums xs) `union` subsums xs I forgot something very important, namely that the common subexpression subsums xs has to be shared euler201 = map snd . filter ((==50) . fst) . subsums $ squares where subsums [] = singleton (0,0) subsums (x:xs) = let s = subsums xs in map (\(n,s) - (n+1,s+x)) s `union`s Otherwise, this exercise would be pointless and the runtime exponential ... :O Regards, apfelmus ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] uvector and the stream interface
On 14.07.2008, at 20:48, Don Stewart wrote: Yes, we have long been discussing a generic Stream library to which the various sequence structures can be translated to and from. Already it is useful to say, stream bytestrings into uvectors and out to lists. could the Stream interface be made public in uvector for writing custom adapters? If people are using uvector or stream-fusion (the list version) and are interested in interop please let Roman, Duncan and I know, so we can think more about how best to make it all play together. i'd be interested, just have to gather a little more infrastructure before i start working on real algorithms. sk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Linker problems linking FFI import call in Windows
On 7/16/08, Olivier Boudry [EMAIL PROTECTED] wrote: On Tue, Jul 15, 2008 at 11:51 PM, PJ Durai [EMAIL PROTECTED] wrote: I am trying to import some functions from a windows DLL. I am getting strange errors. (This used to work with previous versions of GHC. 6.6 I think.). You may have to create an import library for the DLL. I had a similar problem and solved it that way. Look at http://www.emmestech.com/moron_guides/moron1.html for advices on how to create such a library. My problem was that the exports in the dll were prefixed with an underscore. I had to remove them from the .def file before creating the import library. I do have the import library. It came with the DLL. It links properly when I use CCALL on the haskell import statements. Doesnt link when I use STDCALL. It looks for function name with something like '@4 or @8' tacked on at the end. Not sure what that is all about. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Linker problems linking FFI import call in Windo ws
On Wed, 16 Jul 2008 10:22:46 -0600, you wrote: I do have the import library. It came with the DLL. It links properly when I use CCALL on the haskell import statements. Doesnt link when I use STDCALL. It looks for function name with something like '@4 or @8' tacked on at the end. Not sure what that is all about. This is known as name mangling. See the Wikipedia article for more info: http://en.wikipedia.org/wiki/Name_mangling Steve Schafer Fenestra Technologies Corp. http://www.fenestra.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Fixed-Point Combinators
Hello, while studying for a exam I came across this little pearl: Y = (L L L L L L L L L L L L L L L L L L L L L L L L L L L L) where L = λabcdefghijklmnopqstuvwxyzr. (r (t h i s i s a f i x e d p o i n t c o m b i n a t o r)) posted by Cale Gibbard to this list. Now I'm wondering how exactly does one finde such awesome λ expressions? Is there some mathemagical background that lets one conjure such beasts? Adrian PGP.sig Description: Signierter Teil der Nachricht ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Fixed-Point Combinators
Hello Adrian, Wednesday, July 16, 2008, 11:17:05 PM, you wrote: L = ?abcdefghijklmnopqstuvwxyzr. (r (t h i s i s a f i x e d p o i n t c o m b i n a t o r)) does one finde such awesome ? expressions? Is there some mathemagical background that lets one conjure such beasts? full search? :) -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
RE: [Haskell-cafe] A type signature inferred by GHCi that is rejected when written explicitly
| I myselft don't understand why GHCi doesn't accept the type it
| infered as an explicit signature ...
I've known about this confusing behavior for some time, and the design goal
that the compiler should not infer a type that it can't check seems Clearly
Right. Stupidly, though, I had not previously realized that it's all a
consequence of GHC's rather relaxed approach to ambiguity. Here's a little
section from a some notes I'm working on that may clarify. Bottom line: I
intend to change GHC (I hope for 6.10) so that if a definition gets an inferred
type that could not appear as a type signature, the definition will be rejected
as ambiguous.
Comments welcome. (Do cc me since I no longer guarantee to read all of the
wisdom of Haskell Café.)
Simon
Consider this
\begin{code}
class C a b where
op :: b - a - a
instance C [a] b
op _ x = x
instance Ord b = C (Maybe a) b
op _ x = x
f x = op undefined x
\end{code}
GHC currently infers the type
\begin{code}
f :: C a b = a - a
\end{code}
Despite the fact that @b@ is not mentioned after the @=@, nor is
there a functional dependency, @f@ can be called unambiguously, thus
\begin{code}
f [True]
\end{code}
This call gives rise to the constraint @(C [Bool] b)@, for some undetermined
type @b@, and the instance declaration fires happily. However, the call
@(f Nothing)@ will give the constraint @(Ord b)@, which cannot be discharged
without knowing @[EMAIL PROTECTED] Some calls are ambiguous and some are not.
GHC
defers this choice to the caller, unless it can readily see that every
call will be ambiguous.
However, this relaxed approach has a big disadvantage: \emph{you cannot
write a type signature for @[EMAIL PROTECTED]:
\begin{code}
f :: C a c = a - a
f x = op undefined x
\end{code}
Now GHC has no way to prove that the given constraint @(C a c)@
proves the wanted constraint @(C a b)@, using plain syntactic matching.
So we propose the following:
\begin{itemize}
\item Every inferred type (and every type written by the programmer)
must be unambiguous.
\item A type $\forall \overline{a}.C \Rightarrow \rho$ is unambiguous iff
from $C$ we can deduce $C[\overline{b'/b}]$ where $\overline{b} = \overline{a}
\setminus fv(\rho)$,
and $\overline{b'}$ are fresh. That is, freshen the variables in $C$ that
are not mentioned in the type $\rho$, and check that you can can deduce
the freshened $C'$ from $C$.
\end{itemize}
This would reject the definition @f@, either with or without a type
signature.
| -Original Message-
| From: [EMAIL PROTECTED] [mailto:haskell-cafe-
| [EMAIL PROTECTED] On Behalf Of Pablo Nogueira
| Sent: 08 July 2008 09:03
| To: Alfonso Acosta
| Cc: Haskell-Cafe
| Subject: Re: [Haskell-cafe] A type signature inferred by GHCi that is
| rejected when written explicitly
|
| I myselft don't understand why GHCi doesn't accept the type it
| infered as an explicit signature ...
|
| I think it has to do with the following:
|
| Looking at the type errors, they seem to indicate that the type
| checker is being general and does not assume the |From| and |To|
| relations are between
| a type |t| and (s (t x) x)| but, in general, between |t| and |s (t' x) x|.
|
| Given that
|
| from :: (From a1 c1 x) = a1 x - c1 x
| to :: (To a2 c2 y) = c2 y - a2 y
| bimap :: Bifunctor s = (t1 - t3) - (t2 - t4) - s t1 t2 - s t3 t4
|
| During type checking the following equations spring up:
|
| c2 y = s t3 t4
| c1 x = s t1 t2
| t2 = x
| t4 = y
| t1 = a1 x
| t3 = a2 y
|
| That'd give the same type as that inferred, but somehow new variables
| |a11| and |a12| appear.
|
| caused by a lack of functional dependencies.
| class From a c x | a - c where
| class To a c y | c - a where
| ... hushes GHCi. The question now is, of course, if the new
| dependencies are too restrictive for your problem.
|
| They are of little avail given the instances I define:
|
| instance Bifunctor s = From (Fix s) (s (Fix s x)) x where
| from = out
|
| instance Bifunctor s = To (Fix s) (s (Fix s y)) y where
| to = In
| ___
| Haskell-Cafe mailing list
| Haskell-Cafe@haskell.org
| http://www.haskell.org/mailman/listinfo/haskell-cafe
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RE: [Haskell-cafe] Re: Haskell on ARM (was Re: ANN: Topkata)
| Linux Nokia-N810-42-19 2.6.21-omap1 #2 Fri Nov 16 16:24:58 EET 2007 | armv6l unknown | | I would love a working GHC implementation on it, if for nothing else | than how awesome it would be. Whether that means using a C back-end or | native compilation doesn't matter to me so much. | | I might be one to attempt this, as I know C and ARM-ish asm decently | well and have a powerful desktop to compile on. I have no familiarity | with GHC internals, though. Lastly, I won't have anything like the time | to attempt this seriously until mid-September or so. That's good. John Dias is hard at work on GHC's back end, and we should be in reasonable shape by mid Sept. Better still a month later... Keep us posted with what you do. Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] curl installation
Hello, I'm trying to install the curl package 1.3.2.1 for haskell, I'm using Ubuntu and I've already installed curl-7.18.2. I can't get rid of the configuration error. According to the log entry the curl.h doesn't exist. Shell output: runghc Setup.hs configure Configuring curl-1.3.2.1... checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ANSI C... none needed checking how to run the C preprocessor... gcc -E configure: error: curl libraries not found, so curl package cannot be built See `config.log' for more details. Part of Log entry: configure:2439: gcc -E conftest.c conftest.c:9:23: error: curl/curl.h: No such file or directory configure:2445: $? = 1 configure: failed program was: | /* confdefs.h. */ | | #define PACKAGE_NAME Haskell curl package | #define PACKAGE_TARNAME curl | #define PACKAGE_VERSION 1.1 | #define PACKAGE_STRING Haskell curl package 1.1 | #define PACKAGE_BUGREPORT [EMAIL PROTECTED] | /* end confdefs.h. */ | #include curl/curl.h configure:2469: error: curl libraries not found, s o curl package cannot be built See `config.log' for more details. Any ideas? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: Issue 77 - July 16, 2008
--- Haskell Weekly News http://sequence.complete.org/hwn/20080716 Issue 77 - July 16, 2008 --- Welcome to issue 77 of HWN, a newsletter covering developments in the [1]Haskell community. Announcements Takusen 0.8.3. Alistair Bayley [2]announced the release of [3]Takusen 0.8.3, with ODBC support, more Cabal improvements, bug fixes, and some basic result-set validation. Launching Haskell Group in Vancouver, Canada. Jon Strait [4]announced that a [5]Haskell Programmers Group has been created in Vancouver; the first meeting is scheduled for next Monday, July 21st. Feel free to join the Google Groups list to be notified of future events, or just show up to a meeting to bounce ideas and questions off of other Haskell programmers. Sphinx full-text searching client on Hackage. Chris Eidhof [6]announced work on a [7]client for the [8]sphinx full-text search engine. Help hacking on it, testing it or improving documentation is welcome. haskell-src-exts 0.3.5. Niklas Broberg [9]announced that the [10]haskell-src-exts package is now updated to understand the current version of Template Haskell syntax. Bug reports welcome. Prime time for Haskell. Janis Voigtlaender [11]announced that Haskell STM is featured in an [12]article in this month's Communications of the ACM. vector 0.1 (efficient arrays with lots of fusion). Roman Leshchinskiy [13]announced an initial release of the [14]vector library, which will eventually provide fast, Int-indexed arrays with a powerful fusion framework. Galois Tech Talks: Stream Fusion for Haskell Arrays. Don Stewart [15]announced that he was giving this week's Galois Tech Talk, on stream fusion for Haskell arrays. The talk was yesterday, July 15, but hopefully some sort of recording or slides will be made available. protocol-buffers. Chris Kuklewicz [16]announced a very early version of the [17]protocol-buffers package, a Haskell interface to Google's newly released [18]data interchange format. GHC IRC meeting. Simon Marlow [19]announced the (first weekly?) IRC meeting to discuss GHC, a scheduled time when the developers turn up on #ghc, discuss current topics around GHC, and users can chime in with questions, points for discussion, complaints and so on. The first meeting took place on July 16 at 1600 BST (UTC +1)/0800 PDT (UTC-7)/1100 EDT (UTC-4), in the #ghc channel on chat.freenode.net; hopefully this will become a weekly event. Google Summer of Code Progress updates from participants in the 2008 [20]Google Summer of Code. GHC API. Thomas Schilling (nominolo) is working on [21]improvements to the GHC API. He recently [22]asked for comments on a proposed refactoring to the GHC API, creating a new Ghc monad to capture error handling and single-threaded use of Sessions. GHC plugins. Max Bolingbroke is working on dynamically loaded plugins for GHC. [23]This week, he wrote a ton of Haddock documentation for GHC internals. He also added the ability for compiler plugins to generate their own source annotations, to allow plugins to use intermediate results from previous plugins. He's currently working on an exciting, secret feature: tune in next week to find out what it is! Generic tries. Jamie Brandon is working on a library for efficient maps using generalized tries. Jamie is [24]currently working on, tweaking the [25]api, writing tests and writing reference implementations on sorted and unsorted association lists. Hoogle 4. Neil Mitchell (ndm) is working on [26]Hoogle 4. [27]This week, he worked on type search and database generation. Next week he plans to finish up type search and release and command-line version. Language.C. Benedikt Huber (visq) is [28]working on Language.C, a standalone parser/pretty printer library for C99. DPH physics engine. Roman Cheplyaka (Feuerbach) is working on a [29]physics engine using [30]Data Parallel Haskell. Cabal dependency framework. Andrea Vezzosi (Saizan) is working on a [31]make-like dependency analysis framework for Cabal. Libraries Proposals and extensions to the [32]standard libraries. adding split to Data.List. Gwern Branwen [33]proposed adding some split-like functions to Data.List. Will they actually get added this time? Will people be able to agree on one of the seventeen possible sets of semantics? Tune in next time... Discussion GHC API: monad and error handling. Thomas Schilling [34]asked for comments on a proposed refactoring to the GHC API, creating a new Ghc monad to capture error handling and single-threaded use of Sessions. Jobs Research positions on Modeling and Analyzing Software Adaptation, University of Koblenz. Ralf Lammel [35]announced two research
Re: [Haskell-cafe] curl installation
noahaon: Hello, I'm trying to install the curl package 1.3.2.1 for haskell, I'm using Ubuntu and I've already installed curl-7.18.2. I can't get rid of the configuration error. According to the log entry the curl.h doesn't exist. Shell output: runghc Setup.hs configure Configuring curl-1.3.2.1... checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ANSI C... none needed checking how to run the C preprocessor... gcc -E configure: error: curl libraries not found, so curl package cannot be built See `config.log' for more details. Part of Log entry: configure:2439: gcc -E conftest.c conftest.c:9:23: error: curl/curl.h: No such file or directory configure:2445: $? = 1 configure: failed program was: | /* confdefs.h. */ | | #define PACKAGE_NAME Haskell curl package | #define PACKAGE_TARNAME curl | #define PACKAGE_VERSION 1.1 | #define PACKAGE_STRING Haskell curl package 1.1 | #define PACKAGE_BUGREPORT [EMAIL PROTECTED] | /* end confdefs.h. */ | #include curl/curl.h configure:2469: error: curl libraries not found, s o curl package cannot be built See `config.log' for more details. Check where curl/curl.h is on your system. It is possible the development headers are missing? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: curl installation
Marco Túlio Gontijo e Silva marcot at riseup.net writes: Em Qua, 2008-07-16 às 19:50 +, Thomas Fuhrmann escreveu: Hello, Hello. conftest.c:9:23: error: curl/curl.h: No such file or directory http://packages.ubuntu.com/search?searchon=contentskeywords=curl.hmode=exactfilenamesuite=hardyarch=any Hope it helps. Thanks a lot, the GnuTLS package wasn't yet installed. Bye ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
AW: [Haskell-cafe] Fixed-Point Combinators
--- Adrian Neumann [EMAIL PROTECTED] schrieb am Mi, 16.7.2008: Von: Adrian Neumann [EMAIL PROTECTED] Betreff: [Haskell-cafe] Fixed-Point Combinators An: Haskell Cafe mailing list haskell-cafe@haskell.org Datum: Mittwoch, 16. Juli 2008, 21:17 Hello, while studying for a exam I came across this little pearl: Y = (L L L L L L L L L L L L L L L L L L L L L L L L L L L L) where L = λabcdefghijklmnopqstuvwxyzr. (r (t h i s i s a f i x e d p o i n t c o m b i n a t o r)) posted by Cale Gibbard to this list. Now I'm wondering how exactly does one finde such awesome λ expressions? Is there some mathemagical background that lets one conjure such beasts? Have a look at http://citeseer.ist.psu.edu/251224.html In this paper Jeroen Fokker describes how to derive a one-combinator basis from the SKI combinators in a systematic way. Maybe it can give you some hints how to treat this kind of problem. __ Gesendet von Yahoo! Mail. Dem pfiffigeren Posteingang. http://de.overview.mail.yahoo.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Haskell on ARM (was Re: ANN: Topkata)
Simon Peyton-Jones wrote: | Linux Nokia-N810-42-19 2.6.21-omap1 #2 Fri Nov 16 16:24:58 EET 2007 | armv6l unknown | | I would love a working GHC implementation on it, if for nothing else | than how awesome it would be. Whether that means using a C back-end or | native compilation doesn't matter to me so much. | | I might be one to attempt this, as I know C and ARM-ish asm decently | well and have a powerful desktop to compile on. I have no familiarity | with GHC internals, though. Lastly, I won't have anything like the time | to attempt this seriously until mid-September or so. That's good. John Dias is hard at work on GHC's back end, and we should be in reasonable shape by mid Sept. Better still a month later... Keep us posted with what you do. Simon Well, I've documented three attempts in detail on the ArmLinuxGhc Trac page[1]. In short, it doesn't work. 6.8 and 6.9 fail, expectedly, since bootstrapping is known to be broken[2]. 6.6 might be made to work, but it didn't work with moderate effort and so it seems foolish to invest that sort of energy into an old version when the back end is being overhauled. As it appears that the task will be much easier after the back end changes, this project is effectively on hold until the 6.10 release. In particular, bootstrapping needs to work. There is a bug[2] about this with milestone set to 6.10.1. Hopefully a quick-and-dirty unregisterised port will be easy after that, with registerised and possibly even native code-gen on the horizon. One question that has come up is, what external tools does GHC need to build binaries on a given platform? When going via-c, is a complete C toolchain necessary? When doing native code-gen, are ld or ar required, or other binutils? If we magically had a 6.9 that would generate ARM binaries, what would it take to run binaries built in the dev environment on the device? Would it take more to run GHC itself on the device? Braden Shepherdson shepheb [1] http://hackage.haskell.org/trac/ghc/wiki/ArmLinuxGhc [2] http://hackage.haskell.org/trac/ghc/ticket/1346 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] FFI and struct arguments
Hi,
I tried googling and searching the haskellwiki about this but wasn't
lucky enough. My question is: is there a way to send struct arguments
to C functions via the FFI or do I need to create a C wrapper? I guess
there isn't, and while I can live without it, I'd like to leave no
doubt.
Details:
I have something like
typedef struct vect {
float x,y;
} vect;
void func(vect v);
=
on the C side and
-- Please disregard float /= Float, just an example :)
data Vector = Vector Float Float
instance Storable Vector where
...
on the Haskell side, and I want to call func with Vector as argument.
Now, Vector isn't a basic FFI type, although it implements Storable.
So does that mean that I need to create something like
void funcWrapper(vect *v) {
func(*v);
}
and then allocate some temporary memory on the Haskell side to use func?
Cheers!
--
Felipe.
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