Brandon S. Allbery KF8NH wrote:
My fix would be to have myPrefixOf require the prefix be terminated in
whatever way is appropriate (end of input, white space, operator?)
instead of simply accepting as soon as it gets a prefix match regardless
of what follows.
Maybe you can use notFollowedBy
Erik de Castro Lopo wrote:
However after reading the hackage descriptions of both Transformers and
MTL, it seems that they share a very similar heritage. I therefore hacked
the iteratee.cabal file and replaced the build-depends on transformers
with one on mtl and the package built quite happily.
| Is there any way to define type-level multiplication without requiring
| undecidable instances?
|
| No, not at the moment. The reasons are explained in the paper Type
| Checking with Open Type Functions (ICFP'08):
|
|http://www.cse.unsw.edu.au/~chak/papers/tc-tfs.pdf
|
| We want to
On Tuesday 13 October 2009 02:46:29 Erik de Castro Lopo wrote:
Hi all,
I've just received the following error message:
headers.hs:6:7:
Could not find module `Control.Monad.Identity':
it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2
I'm trying to use the
From: Erik de Castro Lopo mle...@mega-nerd.com
Well Iteratee built with MTL passes all the tests that shipped with it
so I suppose it must be correct.
Unfortunately the iteratee tests aren't exhaustive, but if it builds
with MTL it should work. I'm more surprised that it built just by
On 2009-10-07 17:29, Robert Atkey wrote:
A deep embedding of a parsing DSL (really a context-sensitive grammar
DSL) would look something like the following. I think I saw something
like this in the Agda2 code somewhere, but I stumbled across it when I
was trying to work out what free applicative
There is no difficulty in principle with Haskell on JVM. There are, however,
some obstacles in practice, as this page describes:
http://haskell.org/haskellwiki/GHC:FAQ#Why_isn.27t_GHC_available_for_.NET_or_on_the_JVM.3F
The way stands open for someone with design taste, knowledge of the JVM,
Hugo Gomes wrote:
The Glorious Glasgow Haskell Compilation System, version 6.10.4
with old-time-1.0.0.2 and time-1.1.2.4
This is a standard haskell platform on a windows xp. Cabal install
didn't work complaining about missing instances of typeable for posix
time and other datatypes, yet,
On 10/12/09, Martijn van Steenbergen mart...@van.steenbergen.nl wrote:
Brandon S. Allbery KF8NH wrote:
My fix would be to have myPrefixOf require the prefix be terminated in
whatever way is appropriate (end of input, white space, operator?)
instead of simply accepting as soon as it gets a
On Tue, Oct 13, 2009 at 3:37 AM, Simon Peyton-Jones
simo...@microsoft.com wrote:
[...]
It's also worth noting that while undecidable instances sound scary, but
all it means is that the type checker can't prove that type inference will
terminate. We accept this lack-of-guarantee for the
On Tue, Oct 13, 2009 at 3:37 AM, Simon Peyton-Jones
simo...@microsoft.com wrote:
| Is there any way to define type-level multiplication without requiring
| undecidable instances?
|
| No, not at the moment. The reasons are explained in the paper Type
| Checking with Open Type Functions
Yes, there are simple H-M examples that are exponential.
x0 = undefined
x1 = (x1,x1)
x2 = (x2,x2)
x3 = (x3,x3)
...
xn will have a type with 2^n type variables so it has size 2^n.
-- Lennart
On Tue, Oct 13, 2009 at 6:04 PM, Brad Larsen brad.lar...@gmail.com wrote:
On Tue, Oct 13, 2009 at 3:37
2009/10/13 Lennart Augustsson lenn...@augustsson.net:
Yes, there are simple H-M examples that are exponential.
x0 = undefined
x1 = (x1,x1)
x2 = (x2,x2)
x3 = (x3,x3)
...
xn will have a type with 2^n type variables so it has size 2^n.
Reformulated:
let dup x = (x,x)
:t dup . dup . dup . dup
On Tue, Oct 13, 2009 at 12:32 PM, Serguey Zefirov sergu...@gmail.com wrote:
2009/10/13 Lennart Augustsson lenn...@augustsson.net:
Yes, there are simple H-M examples that are exponential.
x0 = undefined
x1 = (x1,x1)
x2 = (x2,x2)
x3 = (x3,x3)
...
xn will have a type with 2^n type variables
Am Dienstag 13 Oktober 2009 18:04:52 schrieb Brent Yorgey:
Brent
* Some smart-alecks might pipe up with something about unsafePerformIO
here. But that's not a cure, it's more like performing an emergency
tracheotomy with a ballpoint pen.
Quote of the month!
A few weeks ago I wrote a patch that adds reverse dependencies to
hackage [1]. I have know hosted a small test hackage which
demonstrates this feature. It can be found here:
http://bifunctor.homelinux.net/~roel/hackage
Browse to your favorite packages and find out how much other packages
depend
Hi Kim-Ee,
This pattern shows up in Applicative programming with effects in showing
that the composition of applicatives is applicative: (*) = liftA2 (*),
and pure = pure.pure . (Really, you have to manage newtype wrappers as
well. See the TypeCompose library.)
- Conal
On Mon, Oct 12, 2009
Hi Dimitry,
ghc-core is a pretty-printer for GHC's internal Core language (you can
get a non-pretty-printed version simply by compiling with (IIRC)
-dverbose-core2core). This is what we actually optimize and generate
code from, and the formatting of this output might change at any time.
This is
Yes, ansi-terminal supports this. Try:
setSGR [SetBlinkSpeed NoBlink]
(http://hackage.haskell.org/packages/archive/ansi-terminal/0.5.0/doc/html/System-Console-ANSI.html)
Cheers,
Max
2009/10/12 Iain Barnett iainsp...@gmail.com:
On 11 Oct 2009, at 15:30, Andrew Coppin wrote:
Iain Barnett
Err, I managed to completely misread your email. Sorry.
Unfortunately, ansi-terminal does NOT support disabling the echo and I
don't plan to support it. However, given that I already provide
non-ANSI features from it, patches would be happily accepted :-)
Cheers,
Max
2009/10/13 Max Bolingbroke
Max,
Thanks for the explanation. So, the extcore library is expected to
match the spec in
http://www.haskell.org/ghc/docs/6.10.4/html/ext-core/core.pdf and the
core itself can be produced with -fext-core, correct? I think it might
be interesting for people working on alternative backends
On Tue, 2009-10-13 at 21:30 +0200, Roel van Dijk wrote:
I also noticed that work is underway to implement a new hackage-server
[2] based on happstack. If people find this feature useful I could
also write a patch against the hackage-server code base [3].
That would be much appreciated.
Can someone explain why the one stack overflows and the other one doesn't?
iterateNTimes i f x = foldr (.) id (replicate i f) $ x
tntIO :: IO Int
-- same as replicateM (10^6) $ return 0 , and same as sequence .
replicate (10^6) $ return 0
tntIO = iterateNTimes (10^6) (ap . liftM (:) . return $ )
Don Stewart d...@galois.com writes:
Hey all,
Following up on this, I'm presenting a position paper tomorrow on the
use of EDSLs to improve productivity and lower cost when developing code
for new high performance architectures (like GPUs).
On Tuesday 13 October 2009 1:06:41 pm Brad Larsen wrote:
Good example! I have a feeling that the `dup' example is a bit
contrived, not something that one would be likely to find in the wild.
This is, after all, why HM is useful. In general, there are programs that take
exponential time/space
On Tue, Oct 13, 2009 at 9:37 AM, Simon Peyton-Jones
simo...@microsoft.comwrote:
| Is there any way to define type-level multiplication without requiring
| undecidable instances?
|
| No, not at the moment. The reasons are explained in the paper Type
| Checking with Open Type Functions
correction, should be:
iterateNTimes i f x = foldr (.) id (replicate i f) $ x
tntIO :: IO Int
-- same as replicateM (10^6) $ return 0
tntIO = return . head = (iterateNTimes (10^6) (ap . liftM (:) .
return $ 0) (return [])) -- produces output
tntMb :: Maybe Int -- overflows
tntMb = return . head =
Of all the projects that are in the HackageDB, how many, or what % do you
say developed an EDSL?
daryoush
On Tue, Oct 13, 2009 at 3:06 PM, Xiao-Yong Jin xj2...@columbia.edu wrote:
Don Stewart d...@galois.com writes:
Hey all,
Following up on this, I'm presenting a position paper tomorrow
Martin Sulzmann wrote:
Undecidable instances means that there exists a program for which there's
an infinite reduction sequence.
I believe this may be too strong of a statement. There exists patently
terminating type families that still require undecidable
instances in GHC. Here is an example:
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