Register now - for Amazing Talks and Thrilling Tutorials:
HaL-10 Haskell in Leipzig December 4/5
http://nfa.imn.htwk-leipzig.de/HAL2015/
Opens with an invited talk by Joachim Breitner on MonadFix,
closes with a presentation of Liquid Haskell by Michael Beaumont.
- Johannes
HaL-10 Haskell in Leipzig (December 4/5)
http://nfa.imn.htwk-leipzig.de/HAL2015/
We are proud to present Joachim Breitner (nomeata)
as our invited speaker.
The submission deadline (November 2) is approaching!
See you - Johannes Waldmann (PC chair
trägen
* 5. November: Bekanntgabe des Programms
* bis 27. November: Anmeldung
* 4. und 5. Dezember: Workshop
Herzliche Grüße, Johannes Waldmann, Leipzig.
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, web services, etc.) Rewriting techniques play a relevant
role in computing research, education, and industry.
International Schools on Rewriting are promoted
by the IFIP Working Group 1.6 Term Rewriting.
ISR 2015 organizing committee:
Alfons Geser, Christine Klöden, and Johannes Waldmann
Cali, Colombia
Janis Voigtländer, Universität Bonn, Germany
Johannes Waldmann (chair), HTWK Leipzig, Germany
Peter J. Stuckey, NICTA and the University of Melbourne, Australia
René Thiemann, University of Innsbruck, Austria
Organising Committee
Stefan Brass (chair) Universität
, Brazil
William Byrd, University of Utah
Michael Hanus , Universität Kiel, Germany
Herbert Kuchen, Universität Münster, Germany
Carlos Olarte, DECC, Pontificia Universidad Javeriana Cali, Colombia
Janis Voigtländer, Universität Bonn, Germany
Johannes Waldmann (chair), HTWK
Have you applied Yesod recently? ( http://www.yesodweb.com/ )
Would you enjoy presenting your Yesod project
to C.S. master's students during a course (Oberseminar)
that I'm teaching at HTWK Leipzig currently?
Then email me with details: a short description of your project,
preferrably including
Henning Thielemann lemming at henning-thielemann.de writes:
.. package set-cover for solving exact set cover problems.
http://hackage.haskell.org/package/set-cover
It's hard to evaluate whether one could use the library
because there's essentially no visible documentation.
E.g., what does
Problem solved: with mate, use atril instead of evince.
(I think it is a gtk2/tgk3 issue and it's got nothing to do with xmonad.)
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Mateusz Kowalczyk fuuzetsu at fuuzetsu.co.uk writes:
I always thought [hayoo] was just Hoogle with more indexed docs.
Wait - there's a semantic difference:
hoogle does understand type signatures
(e.g., it can specialize them, or flip arguments of functions)
while hayoo just treats signatures
I tried using lilypond ( http://www.lilypond.org/ )
for typesetting of sheet music.
While the output looks nice, the input language IMHO is quite horrible,
because the underlying data/execution model is underspecified.
For some parts, it tries to describe the logical structure of the score;
but
Hi. I am using xmonad + mate (on fedora 19)
and evince (PDF viewer) seems unresponsive:
it reacts to my (mouse) input
only after switching to another screen and back.
Any hints? - Thanks, J. W.
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Daryoush Mehrtash dmehrtash at gmail.com writes:
What does restricted form mean?
non-restricted: e.g., f (f x y) z = f x (f y z))
restricted: the shape of function declarations in Haskell
(where lhs is a pattern)
definitions are terminating ...
non-termination: an equation like f x y = f
Hi.
we are using template Haskell to splice in some code
that is produced by reading and transforming the contents of another file.
now, if this other file is touched (by editing),
but not the main file, then ghc (and cabal) do not realize
that the main file does need to be recompiled.
is
13th International Workshop on Termination (WST)
Centro Residenziale Universitario di Bertinoro (near Bologna, Italy)
http://www.imn.htwk-leipzig.de/WST2013/
submission: July 22, 2013
notification: July 25, 2013
final version: August 10, 2013
workshop: August 29 - 31, 2013
The
Dear all.
Still one week to go: submit your results and questions on all things
related to termination and bounded resource consumption
(of user programs, of type checkers, etc.)
to the Workshop on Termination. We are specifically encouraging
contributions from the Haskell (and Agda, and Idris)
Code which is part of some expression should be indented
further in than the beginning of that expression [...]
Yes. Then the next question is how much further in.
My answer is: it does not matter, but make it consistent (like 4 spaces),
with the implication that indentation
Unable to locate executable for z3
well, do you really have z3 in the $PATH?
what does 'which z3' answer?
I used this for installation of z3:
python scripts/mk_make.py --prefix=/usr/local
and note that the install script says:
Z3 shared libraries were installed at /usr/local/lib, make sure
What is the recommended method
to find the exact reason for a stack overflow
(when running a Haskell program compiled with ghc)?
When I compile with -prof -auto-all, and run with +RTS -xc,
I see a very short call stack, which can't be right.
But that's probably because I am calling some library
Aleksey Uymanov s9gf4ult at gmail.com writes:
Try to use heap profiling. There is very high probability that the
problem is because of space leak.
Really? Would it help in the standard example:
main = print $ foldr (+) 0 [1 .. 1::Int]
this leaks space (that is, cannot run in small
Roman Cheplyaka roma at ro-che.info writes:
http://feuerbach.github.io/standalone-haddock/
yes, awesome!
I took me a while to figure out I need to add
--package-db $HOME/.ghc/x86_64-linux-7.6.3/package.conf.d
um, where's --hyperlink-source ?
- J.W.
deadline is June 1!
Best regards - Kristoffer H Rose and Johannes Waldmann.
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Jose A. Lopes jose.lopes at ist.utl.pt writes:
unionWith :: Ord k = (a - b - c) - Map k a - Map
k b - Map k c
what should be the result of
unionWith undefined (M.singleton False 42) (M.singleton True bar) ?
perhaps you mean intersectionWith, which already has the type you want.
-
Jose A. Lopes jose.lopes at ist.utl.pt writes:
What makes it an interesting example ?
it shows that your proposed type for unionWith is not reasonable.
why would you want to use undefined in that particular case?
the two argument maps have disjoint key sets,
so the combining function will
Hal8 - Haskell in Leipzig, June 21.
visit the workshop web site for program and registration:
http://www.bioinf.uni-leipzig.de/conference-registration/13haskell
See you - Johannes Waldmann.
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http://hackage.haskell.org/package/intern
what does this package do? OK, I can read efficient hash consing
but what does it mean exactly? and how would I actually use it?
- J.W.
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https://github.com/ekmett/intern/blob/master/examples/Term.hs
sure I found this but that still does not say much.
I known generally what hash consing is
(and that's why I think I might want to use this package)
but I don't see what is the (implied) contract for this implementation:
It looks
(U Utrecht)
Keisuke Nakano (UEC Tokyo)
Kristoffer H Rose (IBM Watson) (co-chair)
Christian Sternagel (JAIST)
Janis Voigtländer (U Bonn)
Johannes Waldmann (HTWK Leipzig) (co-chair)
Dates:
May 21: deadline for submissions
May 28: notification of acceptance
June 27
Adrian May adrian.alexander.may at gmail.com writes:
this decision to change the default syntax in GHC7
what decision? what syntax? here's the release notes (7 vs. 6)
http://www.haskell.org/ghc/docs/7.0.1/html/users_guide/release-7-0-1.html
I guess you are referring to hierarchical module
Byron Hale byron.hale at einfo.com writes:
I was just in the process of trying to get Haskell 7.6 installed.
You cannot install Haskell 7.6. Haskell is a language.
You can install a language implementation (compiler/interpreter).
There may be several. You can also install a set of
Alexander Kjeldaas alexander.kjeldaas at gmail.com writes:
cabal install --upgrade-dependencies `eval echo $(ghc-global-constraints
)` package-name
for a moment I was reading ghc --global-constraints there ... - J.W.
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Hi. I have ghc-7.6.3 and alex-3.0.5.
When I build https://github.com/jwaldmann/smt-lib
it breaks with Language/SMTLIB/Lexer.x:6:5: Not in scope: `alexAndPred'.
It was working with alex-2.3.5.
I was going t add Can I constrain the alex version in the
cabal file (I recall this is difficult for
Is it still the case that
It just doesn't work to have multiple versions of a wired-in package
(cf. http://hackage.haskell.org/trac/ghc/ticket/5704 )?
ghc-7.6.2 comes with containers-0.5.0.0 and template-haskell-2.8.0.0 .
It seems I can upgrade to containers-0.5.2.1 and use it with no problems
Roman Cheplyaka roma at ro-che.info writes:
ghc is the package that provides the GHC API.
Breaking it should not affect the compiler itself, since it is
statically linked.
Yes. But once ghc (the package) is broken,
it cannot be fixed (except by re-installing ghc (the compiler))?
Roman Cheplyaka roma at ro-che.info writes:
On second thought, are you trying to install it globally?
locally
ghc is installed globally, and local packages should not break it.
still cabal-install says so (and I don't dare to test ...)
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What is the current situation: can we have two types
with overlapping component names in one module?
module M where
data T1 = C1 { foo :: Int }
data T2 = C2 { foo :: String }
It seems not (ghc says: Multiple declarations of 'foo'). This comes close:
Yuras Shumovich shumovichy at gmail.com writes:
Will not it be a nightmare to implement and maintain checker for
overlapping/unused clauses for non-linear patterns?
For sure it does not look straightforward.
Note that there are some results and algorithms
for non-linear patterns, cf. this
)
Christian Sternagel (JAIST)
Janis Voigtländer (U Bonn)
Johannes Waldmann (HTWK Leipzig) (co-chair)
Dates:
May 6: deadline for submissions
May 20: notification of acceptance
June 27: workshop
Submission and Proceedings:
Two categories of submissions are invited:
Extended abstracts
Krzysztof Skrzętnicki gtener at gmail.com writes:
see this documentation on profiling with TH:
http://www.haskell.org/ghc/docs/7.6.1/html/users_guide/template-haskell.html#id624714
GHC cannot load the profiled object code
and use it when executing the splices.
That means I do not get
Albert Y. C. Lai trebla at vex.net writes:
Quantifiers are complicated, but I don't see how explicit is more so
than implicit. [...] I have just seen recently [...]
Great example. I completely agree.
My feeling is that mathematicians use this principle of leaving out
some of the
Tom Ellis tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk writes:
I didn't see an example of quantifiers in the wrong place.
The example was:
every x satisfies P(x,y) for some y
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I absolutely love to use Haskell when teaching
(and I have several years of experience doing it).
And I absolutely dislike it when I have to jump through hoops
to declare types in the most correct way, and in the most natural places.
This is hard to sell to the students. - Examples:
1. for
What am I missing?
I want to use mueval to read a file
that contains instance Serial m a = Serial m (Tree a)
(as in
http://hackage.haskell.org/packages/archive/smallcheck/1.0.2/doc/html/Test-SmallCheck-Series.html)
so I put in my call of mueval:
let Right opts =
Hi, I noticed that compilation of mueval (recent: 0.8.2) breaks
because show (0.5) cannot be built:
it seems the type of Failure changed in QuickCheck (from 2.5 to 2.6).
The build succeeds with --constraint 'QuickCheck2.6' .
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Janis Voigtländer (Univ. Bonn), Johannes Waldmann (HTWK Leipzig)
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Package dependencies are modelled by a relation A depends-on B.
Shouldn't this in fact be two relations:
API-depends-on and implementation-depends-on?
(meaning that A API-depends-on B
iff some type of B is visible to the user of A)
So what we currently have is implementation-depends-on
Alexander Kjeldaas alexander.kjeldaas at gmail.com writes:
There's a third relation, A API-ABI-depends-on B
iff some type of B is used in the hidden binary representation
that is used in backing the API visible to A.
Yes. Does this hold in the example I mentioned?
I think the only
Could the maintainers of show
http://hackage.haskell.org/package/show-0.4.1.2
please add some version bound ( 1 or similar)
for the smallcheck dependency?
Thanks for the quick reaction.
show-0.5 now depends on smallcheck=1.0
This works until the next API-breaking change in smallcheck ...
Since smallcheck-1.0 contains API changes -
Could the maintainers of show
http://hackage.haskell.org/package/show-0.4.1.2
please add some version bound ( 1 or similar)
for the smallcheck dependency?
Thanks - J.W.
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)
Christian Sternagel (JAIST)
Janis Voigtländer (U Bonn)
Johannes Waldmann (HTWK Leipzig) (co-chair)
Dates:
May 6: deadline for submissions
May 20: notification of acceptance
June 27: workshop
Submission and Proceedings:
Two categories of submissions are invited:
Extended abstracts
What is the recommended approach for publishing (on hackage)
a package that depends on external libraries?
In my case, the current version of
http://hackage.haskell.org/package/satchmo
(sources at https://github.com/jwaldmann/satchmo)
depends on minisat-haskell-bindings (in Haskell),
. Leipzig), Henning Thielemann (Univ. Halle),
Janis Voigtländer (Univ. Bonn), Johannes Waldmann (HTWK Leipzig)
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I was running into serious performance problems when printing moderately sized
Doc and Xml data (HaXml goes via Doc).
So I replace Text.PrettyPrint.HughesPJ with Text.PrettyPrint.Leijen.Text,
and patched the HaXml printer in the same way. Now it is running much faster.
This confirms some of the
Petr P petr.mvd at gmail.com writes:
Is there any reason to use
a `par` b `pseq` (a + b)
instead of
a `par` b `par` (a + b)
(better ask this on parallel-haskell?)
It seems to me that the second variant would work as well:
The main thread would block on one of the sparked
Hi. I wanted to do some experiments with GHC Head but
* I cannot use the snapshot bindist:
./configure --prefix=/opt
checking for path to top of build tree... ./configure: line 2138:
utils/ghc-pwd/dist-install/build/tmp/ghc-pwd-bindist: No such file or directory
* I cannot compile snapshot from
read 18780189038289e49 :: Integer
this might be related:
http://hackage.haskell.org/trac/ghc/ticket/5688
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http://article.gmane.org/gmane.comp.lang.haskell.parallel/340
(with follow-up message about rseq = rdeepseq)
- J.W.
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Hayoo has them all [ .. ]
but Hoogle is better with types?
it seems Hayoo only does exact (string?) match on types,
while Hoogle also knows about polymorphisms, permutations etc.
E.g., search for String - Int.
Hoogle finds length :: [a]- Int as well,
I think Hayoo doesn't.
J.W.
Stephen Tetley stephen.tetley at gmail.com writes:
Also Franklyn Turbak and David Gifford's Design Concepts for
Programming Languages is very good (and new!) but huge.
Yes! I like that book very much, and I use it for teaching
semantics and compilation of programming languages.
Semantics - by
programme committee,
Johannes Waldmann.
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Daniel van den Eijkel dvde at gmx.net writes:
... but I use HDBC and I'm happy with it.
including its handling of character encodings?
(That is, do you have, e.g., texts with umlauts in your data?)
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Hi.
I am using hsql-(mysql-)1.8.2
When compiled with ghc-7.6, the resulting executable
does not seem to be able to read strings from the DB correctly
(umlauts do vanish)
while it worked with hsql-(mysql-)1.8.1 and ghc-7.4.
the mysql server says (show variables)
| character_set_client
Justin Paston-Cooper paston.cooper at gmail.com writes:
Can anyone suggest a library written in Haskell which can solve equations
of the form xM(transpose(x)) = y, where x should be an integer vector,
M is an integer matrix and y is an integer?
when in doubt, use brute force:
write this
jeff p mutjida at gmail.com writes:
I've always thought that the essence of iteratees is just CPS
for sure, at some level of abstraction this ought to be true,
since CPS simulates call-by-value in a call-by-name language,
cf. Gordon Plotkin: Call-by-Name, Call-by Value and the Lambda Calculus
While porting some code to 7.6, I'm stuck here:
Preprocessing library ghc-mtl-1.0.1.1...
[1 of 1] Compiling Control.Monad.Ghc ( Control/Monad/Ghc.hs,
dist/build/Control/Monad/Ghc.o )
Control/Monad/Ghc.hs:29:48:
No instance for (DynFlags.HasDynFlags Ghc)
this seems to block hint and mueval.
wren ng thornton wren at freegeek.org writes:
As for whether the default should be infix 9 instead of infixl 9 ...
that was exactly the point of my message. - J.
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I was really surprised at the following:
*Main 1 + 2 * 3
7
*Main ( \ (+) (*) - 1 + 2 * 3 ) (+) (*)
9
because I was somehow assuming that either
a) the Prelude fixities of the operators are kept
b) or they are undefined, so the parser rejects.
but the Haskell standard says Any operator lacking
Sylvia is a lambda calculus visualizer.
Such a thing is certainly nice to have.
I use this one for teaching:
http://joerg.endrullis.de/lambdaCalculator.html
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How is it possible to run 2 different versions of GHC
if you installed the binary packages in standard locations,
look in /usr/local/bin/ghc* : you have ghc-6.12.3, ghc-7.6.1 etc.
and each one knows how to find their libraries.
you can even say cabal install --with-ghc=ghc-7.6.1 foo
Peter Gammie peteg42 at gmail.com writes:
My hBDD bindings are on Hackage.
Great! Perhaps add category: logic in the cabal file?
J.W.
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Are there any Haskell bindings for BDD libraries
(reduced ordered binary decision diagrams)?
E.g., it seems buddy is commonly used
http://packages.debian.org/squeeze/libbdd-dev
and it has an Ocaml binding.
Yes, there is http://hackage.haskell.org/package/obdd
but I need better performance (with
Tim Docker twd2 at dockerz.net writes:
I need to use a more recent version of gcc
Thanks! Yes, that seems to be it.
When building gcc didn't work, it took me a while
to figure out that I was running into this bug:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51935
so I am using mpfr-3.0.1
Dear all,
I need a recent ghc on a not-so-recent (?) CentOS.
The ghc binary package (7.2 or 7.4) does not work
because of a mismatch in the libc version.
ghc-7.0 is working but when I use it to compile 7.4,
it breaks with some linker error (relocation R_X86_64_PC32 ...)
it also suggests
First, why do you think your code is non-optimal?
you don't show your main program, so we don't know what you're measuring.
Just by looking at some types (and not analysing the algorithm):
11 data FilterState a = FilterState {
14 , taps :: [a] -- current delay tap stored values
the State
Dear all,
while doing some benchmarking (*)
I noticed that function s1 is considerably faster than s2
(but I wanted s2 because it looks more natural)
(for n = 1, s1 takes 20 s, s2 takes 13 s; compiled by ghc-7.4.2 -O2)
s1 :: Int - Int
s1 n = sum $ do
x - [ 0 .. n-1 ]
Jonathan Geddes geddes.jonathan at gmail.com writes:
I love Haskell. It is my absolute favorite language.
But I have a very hard time finding places where I can actually use it!
have you considered your head as such a place that should be easy to find.
even just for specifying things,
Ertugrul Söylemez es at ertes.de writes:
Note about []: Don't even mention foldl. The folding combinator
for lists is foldr, period.
Amen.
I ignore foldl in teaching but it will appear
under the name of IEnumerableT.Aggregate(z, f) (from Linq).
Note, the Linq designers got
There are two threads, one which is waits on input via
hGetLine
and another, which should terminate this thread or close this handle.
like this? The trick is to fork the blocking call (hGetLine)
and wait on an MVar. That way, the kill signal can be handled:
{-# language PatternSignatures
Hi.
I want to produce a statically linked executable.
I am trying 'ghc --make -fforce-recomp -static -optl-static Main'
but it gives lots of errors like
(.text+0xfa): undefined reference to `pthread_mutex_unlock'
collect2: ld returned 1 exit status
A similar thing is mentioned here (see
Scott Lawrence bytbox at gmail.com writes:
Adding -optl-pthread fixes it for me.
great! in my case, I also needed to add '-pgml g++'
and together, this seems to work. Thanks.
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Stefan Holdermans stefan at vectorfabrics.com writes:
This package provides an efficient implementation of so-called
signed multisets, which generalise multisets by allowing for
negative membership.
SignedMultiset a = Data.Map.Map a Integer
so what do I gain by using your library?
(what is
Dear Cafe, I have the following types:
type Computer a b = ( a - IO ( Maybe b ) )
type Transformer a b c d = Computer a ( b, c - d )
For example, a SAT solver:
minisat :: Computer CNF Assignment,
and when I use it to solve an application problem
via transformation to SAT, I need
t ::
The following program prints Right (test,Bool,True)
as it should, but it leaves behind in /tmp
two files (name is a long string of digits)
and an empty directory (name is ghcN_N).
... and it deletes the input file (/tmp/Main.hs).
That's not nice. Ideally, I would want to read input
from a
mueval-0.8.1.1
this is actually 0.8.2
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I must be making some obvious mistake here,
but I'm not seeing it. The file name contains O-umlaut,
and the OS handles it fine, but ghci does not like it
(although it accepts umlauts in the contents of the file
(UTF-8) e.g., as a module name)
$ cat fÖÖbar.hs
main = print $ product [1..100]
$
Good: we have mapM, and we have forM ( = flip mapM ) .
Sure this is just a convenience, and indeed
forM xs $ \ x - do ... is quite handy,
especially if xs is really small,
and ... is some larger expression.
Bad: we have map, but we are missing: for ( = flip map ) .
The function is very
Can someone tell me why this is not working
that someone is actually ghci:
Prelude instance (Num a, Add a b) = Add (a - b) where add x y = add (x + y)
interactive:8:30:
Expecting one more argument to `Add (a - b)'
In the instance declaration for `Add (a - b)'
The problem seems to be that numeric literals are polymorphic.
With your code, this works:
*Main let x = 8 :: Int
*Main add x x x :: Int
24
*Main add x x :: Int
16
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Sounds good - but my build fails on ubuntu-11.10:
Building gtksourceview2-0.12.3...
Preprocessing library gtksourceview2-0.12.3...
./gtksourceview2.h:10:48: fatal error: gtksourceview/gtksourceundomanager.h: No
such file or directory
compilation terminated.
gtk2hsC2hs: Error during preprocessing
cabal install --extra-include-dirs=. gtksourceview2
yes this works. thanks! - J.W.
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Can I really rename old.T = new.T_orig ?
It looks as if then tries to load the wrong acid-state snapshot.
The name of your data type doesn't matter as acid-state doesn't store
that on the disk.
I think it does - because file names are state/T/*.log and so on?
J.W.
Couldn't match expected type `Data.Tree.NTree.TypeDefs.NTree XNode'
with actual type `hxt-8.5.4:Data.Tree.NTree.TypeDefs.NTree
hxt-8.5.4:Text.XML.HXT.DOM.TypeDefs.XNode'
perhaps you have installed several (conflicting) versions of
Felipe Almeida Lessa felipe.lessa at gmail.com writes:
data T_orig = T_orig Foo
$(deriveSafeCopy 0 'base ''T_orig)
data T = T Foo Bar
$(deriveSafeCopy 0 'extension ''T)
instance Migrate T where type MigrateFrom T = T_Orig ...
As you can read from deriveSafeCopy's documentation [1],
Dear all,
I can't quite get safecopy to work with acid-state:
old version of code :
data T = T Foo
$(deriveSafeCopy 0 'base ''T)
new version :
data T_orig = T_orig Foo
$(deriveSafeCopy 0 'base ''T_orig)
data T = T Foo Bar
$(deriveSafeCopy 0 'extension ''T)
instance Migrate T where type
dokondr dokondr at gmail.com writes:
It would be great if I could write Web client code in pure Haskell [...]
not exactly Haskell, but you may want to have a look at OPA http://opalang.org/
the idea is that you write all of the application in one
(statically typed, functional) language
and
How could I use haxr (http://www.haskell.org/haskellwiki/HaXR)
to build a stateful server?
It should listen on some port,
and fork threads (inside Haskell land) to handle incoming calls.
Any of the Haskell web frameworks can do this?
I guess this is the same question as:
Michael Snoyman michael at snoyman.com writes:
It seems like the issue is that HaXR uses CGI, whereas you want to tie
it in with a web server, correct?
Yes.
There's a deprecated package[1] to
allow CGI apps to be run on any WAI handler (such as Warp).
why deprecated? what's the problem
Hello.
I can do cabal install --enable-documentation
which is nice because it does
configure, build, haddock and copy in one go,
but I don't see how to pass options
from cabal install to cabal haddock (e.g., --hyperlink-source)
Any hints appreciated, J.W.
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On Mon, Nov 14, 2011 at 9:54 AM, Roman Cheplyaka roma at ro-che.info
wrote:
Does anyone currently work on Test.SmallCheck?
not working on, but I'm using it in teaching.
The one change that I would want in SmallCheck
is that Serial should use size, not depth
(that is, not take the max over
Does this work with ghc -XForeignFunctionInterface ?
http://en.wikibooks.org/wiki/Haskell/FFI#Enumerations
I am getting a syntax error right after #{.
But then, the description is for hsc2hs (not ghc).
And it mentions macros, while C meanwhile has real enums.
Well, at leat one can write enum
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