How do you make Cabal fail?
Let me clarify. I built a package that uses a post-configure hook to do
some settings detection. Under certain circumstances, it can fail. When
this happens, the hook prints fatal error and quits. Unfortunately, I
didn't actually /test/ whether it works. On further
Yves Pare`s wrote:
I cannot help smiling when I hear Java/C#/Python developers telling about
the wondeful features of their languages ;)
(- We have generators! We can _yield_ values! [1]
- Yeah, so nice... We have simple lists... with lazy evaluation)
Just for the record, lazy lists per
Thanks for the feedback. I have two further questions
1. Why is it that the Containers class signature does not allow
instances to be list of list? I suspect it is because x is a constructor.
2. How would I change the Containers class signature to allow instances
to be lists of lists.
Thanks,
On Fri, Jun 10, 2011 at 21:05, Alexander Solla alex.so...@gmail.com wrote:
equivalenceClosure :: (Ord a) = Relation a - Relation a
equivalenceClosure = fix (\f - reflexivity . symmetry . transitivity)
If you want to learn about fix, this won't help you, but if you're
just want the best way to
Le 11/06/2011 11:06, o...@okmij.org a écrit :
The following web page talks about lazy lists and generators
http://okmij.org/ftp/continuations/generators.html
in (perhaps too) great detail.
Oleg, when you mention Icon, you might - perhaps - observe that Griswold
didn't introduce the
OK, so suppose you sit down and write a complicated string parser. Now
how do you test that it works correctly?
One way is to run the parser over a large corpus of real world
samples. This has a number of problems:
* If the parser is for a grammar you just invented yourself, presumably
no
readline has keyboard shortcuts to change from emacs mode to vi and a
separate to go back. Find out what they are and check if they work on
haskeline, you got me wondering but i have no ghci access from here.
Definitely easier than editing a config.
Cheers,
D.
On Sat, Jun 11, 2011 at 00:08, Marc
The problem is that [] alone is not a concrete type - that is what the error is
saying, that [] needs to be applied to another type to yield a concrete type.
IE, you need a list of something, not just the idea of a list. That something
can be polymorphic, so the following works (note the [a]):
On 11/06/11 14:10, Andrew Coppin wrote:
OK, so suppose you sit down and write a complicated string parser. Now
how do you test that it works correctly?
If you have a function that turns a parse tree back into text again,
you can try verifying that a round-trip is the identity function.
On Fri, Jun 10, 2011 at 07:53:58PM -0700, KC wrote:
I've never seen such an easy description in Haskell books.
Is there more going on with Haskell functors?
Note that ML functors and Haskell functors are different things. ML
functors are parameterized modules. Haskell functors are types
Trying to compile GHC7 from source (as the ubuntu repository is still on
GHC6), I came across the following error in the final phase:
libraries/base/GHC/ST.lhs:78:1:
You cannot SPECIALISE `forever'
because its definition has no INLINE/INLINABLE pragma
(or its defining module
Choices, choices.
The first one is to use unit tests. Look at the grammar and make sure the
obvious stuff fails or succeeds. a + b, a :+ b, etc. You can do this at the
Haskell level with parser objects.
Next you can write small samples to test things the unit tests did not. Compare
the output
On Sat, Jun 11, 2011 at 10:06 AM, Sean Perry sha...@speakeasy.net wrote:
Choices, choices.
The first one is to use unit tests. Look at the grammar and make sure the
obvious stuff fails or succeeds. a + b, a :+ b, etc. You can do this at
the Haskell level with parser objects.
Next you can
On Sat, 11 Jun 2011 10:34:47 -0700
Alexander Solla alex.so...@gmail.com wrote:
On Sat, Jun 11, 2011 at 10:06 AM, Sean Perry sha...@speakeasy.net wrote:
Choices, choices.
The first one is to use unit tests. Look at the grammar and make sure the
obvious stuff fails or succeeds. a + b, a
Hi all,
I’m very pleased to announce today the release of the first version of
hashtables, a Haskell library for fast mutable hash tables. The
hashtables library contains three different mutable hash table
implementations in the ST monad, as well as a type class abstracting
out the functions
This is awesome, thanks Greg! I definitely have some code locally that
could benefit from a better hashtable implementation.
Michael
On Sat, Jun 11, 2011 at 9:20 PM, Gregory Collins
g...@gregorycollins.net wrote:
Hi all,
I’m very pleased to announce today the release of the first version of
On Sat, Jun 11, 2011 at 7:10 AM, Andrew Coppin
andrewcop...@btinternet.comwrote:
If you have a function that turns a parse tree back into text again, you
can try verifying that a round-trip is the identity function. Except perhaps
sometimes it isn't. Perhaps a given expression has more than
On Sat, Jun 11, 2011 at 3:19 AM, Max Rabkin max.rab...@gmail.com wrote:
On Fri, Jun 10, 2011 at 21:05, Alexander Solla alex.so...@gmail.com
wrote:
equivalenceClosure :: (Ord a) = Relation a - Relation a
equivalenceClosure = fix (\f - reflexivity . symmetry . transitivity)
If you want to
Yes, the tree was broken for some time between yesterday and today, and you
appear to have gotten unlikely. It should have been fixed now, so you should
try again.
Cheers,
Edward
Excerpts from Scott Lawrence's message of Sat Jun 11 12:44:18 -0400 2011:
Trying to compile GHC7 from source (as
On Sat, Jun 11, 2011 at 4:21 PM, Alexander Solla alex.so...@gmail.com wrote:
_symmetry :: (a, a) - (a, a)
_joinOn :: (Ord a) = (a,a) - Set (a,a) - Set (a,a)
A note on style: we use variables starting with an underline _ just
when they are not used. This kind of use is confusing.
Cheers!
--
I'm looking for a simple implementation of the STG machine to do some
experiments, preferably implemented in something with memory safety.
Performance is totally secondary. I'm also not interested in garbage
collection details, but I do want to look at the contents of the
various stacks.
Does Bernie Pope's http://www.haskell.org/haskellwiki/Ministg work for you?
On 11 June 2011 21:19, Florian Weimer f...@deneb.enyo.de wrote:
I'm looking for a simple implementation of the STG machine to do some
experiments, preferably implemented in something with memory safety.
Performance is
See also:
* STG machine in Coq,
http://www.cs.ox.ac.uk/files/3858/pirog-biernacki-hs10.pdf
http://www.cs.ox.ac.uk/files/3858/pirog-biernacki-hs10.pdfAlso
* ] Jon Mountjoy. The spineless tagless G-machine, naturally. 1998 ACM
SIGPLAN International Conference on Functional Programming,
SIGPLAN
It appears the build is still broken. Sorry! Please stand by, or roll
back the last set of commits.
Edward
Excerpts from Scott Lawrence's message of Sat Jun 11 12:44:18 -0400 2011:
Trying to compile GHC7 from source (as the ubuntu repository is still on
GHC6), I came across the following error
* Thomas Schilling:
Does Bernie Pope's http://www.haskell.org/haskellwiki/Ministg work for you?
MiniSTG might do it, I will definitely look at it. The source
repository is gone, but there's still a tarball on Hackage. I had
hoped for something more interactive, though.
Hello fellow haskellers,
how far does Yesod.Form protect you from invalid input? I'm
particularly interested in what happens, when you submit invalid data to
select fields or radio groups.
Greets,
Ertugrul
--
nightmare = unsafePerformIO (getWrongWife = sex)
http://ertes.de/
For select/radio, the form will not validate. The same is true for
most (all?) other fields.
On Sun, Jun 12, 2011 at 2:35 AM, Ertugrul Soeylemez e...@ertes.de wrote:
Hello fellow haskellers,
how far does Yesod.Form protect you from invalid input? I'm
particularly interested in what happens,
On 06/11/11 09:37 PM, Edward Z. Yang wrote:
Yes, the tree was broken for some time between yesterday and today, and you
appear to have gotten unlikely. It should have been fixed now, so you should
try again.
It's probably not fixed yet, since even last night build fails on
opensolaris
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