Hi.
> I do not know why, my ghc 7.2.1 does not seem to support
> DeriveRepresentable. I compiled the ghc 7.2.1 myself by ghc 7.0.4. All
> options default.
>
> $ ghc Types/TopTalkerRecord.hs
>
> Types/TopTalkerRecord.hs:2:14:
> Unsupported extension: DeriveRepresentable
There's no extension of
Hi there.
> I tried to follow the program of the paper "Scrap your boilerpolate"
> Revolutions. Unfortunately,
> I found the program in the section lifted spine view does not compile in my
> GHC, could anybody
> point out where I am wrong? Many Thanks
>
> My code is posted here http://hpaste.o
e to
start. We are more than happy to answer informal enquiries. Contact
Duncan Coutts, Ian Lynagh or Andres Löh
(http://www.well-typed.com/who_we_are/) for further information,
either by email or IRC.
The deadline for applications is Friday 27th January 2012.
== About Well-Typed
Well-Typed LLP is
Hi.
On Fri, Feb 3, 2012 at 7:44 AM, Ivan Lazar Miljenovic
wrote:
> On 3 February 2012 17:29, Magicloud Magiclouds
> wrote:
>> Thank you. The document does say it more clearly than me.
>> But still, currently, ghc only gives me one option: cannot be built.
>> How about giving me another one: thro
> I am just wanting an option (ignore versions) to take that risk in
> develop environment.
A controlled way of ignoring version constraints (mainly upper bounds,
actually) is certainly on my TODO list for the new solver. The main
issue to work out is a good way how to control the disabled bounds
Hi.
>> --force-allow=foo-1.3
>>
>> with the semantics that all dependencies on foo will be changed to
>> allow foo-1.3 to be chosen. Would that be ok? Other suggestions?
>
> Can't this be integrated with the current --constraint flag?
It could be, but ...
> If the
> constraint is able to be sat
I don't understand what's going on here. Instances for V1 should of
course be defined if they can be! And in this case, a V1 instance
makes sense and should be defined. The definition itself doesn't
matter, as it'll never be executed.
Cheers,
Andres
_
Hi.
>> I don't understand what's going on here. Instances for V1 should of
>> course be defined if they can be! And in this case, a V1 instance
>> makes sense and should be defined. The definition itself doesn't
>> matter, as it'll never be executed.
>
>
> The definition certainly matters:
[...]
> Would you have an example of a type for which it would be useful to have
> a DeepSeq instance, and that would require a V1 instance? I cannot think
> of one now; I originaly thought it would be necessary to permit deriving
> DeepSeq instances for types tagged with "void" types, but as José
> expl
Hi.
> $ cabal install persistent
> Resolving dependencies...
> In order, the following would be installed:
> aeson-0.6.0.2 (reinstall) changes: mtl-2.1.1 -> 2.0.1.0
> persistent-0.9.0.3 (new package)
> cabal: The following packages are likely to be broken by the reinstalls:
> buildwrapper-0.5.2
>
dumping to get at the
> instrumented code before the simplifier's had a go at it.
For the datatype, your use of field labels causes GHC to generate
accessor functions. These aren't covered by your tests. Therefore the
datatype shows as not completely covered.
HTH,
Andres
--
Andres L
a
instance (c1 a, c2 a) => Ext c1 c2 a
typeOfInnerProxy :: ProxyWrapper (Ext Typeable constraint) -> TypeRep
typeOfInnerProxy (ProxyWrapper p) = typeOfArg p
This will certainly require all sorts of undecidable instances :) But
does it work for you?
Cheers,
Andres
--
Andres Löh, Haskell Con
peable Num)' and it would
work.
> then the following would give a type error:
>
> oops :: TypeRep
> oops = typeOfInnerProxy p
Yes, and correctly so. Because Typeable isn't even a superclass of
Num. So there's no way to know that p actually contains a Typeable
proxy.
Hi Chris.
[Sorry if I'm slow responding, but I'm at a summer school right now
and have relatively little time to follow my email.]
> At issue is whether the JustHub Haskell distribution for Enterprise Linux
> and
> the hub hackage for sandboxing development projects and integrating multiple
> GHC
Hi.
> Hackage A depends on magicloud (any) and container (0.4.0.0), and
> hackage magicloud depends on container (any).
> Now I've installed magicloud, using container 0.5.0.0. Then I failed
> to install A, with any solver.
>
> So the solvers are using the status that is installed, not the
> defin
So try "-f-UseExtensions" if you really want that?
Cheers,
Andres
--
Andres Löh, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com
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;. I see that it lists only some of the
dependencies. It's a general phenomenon. I don't understand the way
Hackage lists package dependencies. I'd appreciate if it'd actually
show the whole conditional tree of dependencies.
Cheers,
Andres
--
Andres Löh, Haskell
) -> sigma_1 -> c
~> forall c. (forall a. a -> a) -> sigma_1 -> c
~> forall c. (forall a. a -> a) -> (forall b. sigma_1) -> c
~> forall c. (forall a. a -> a) -> (forall b. sigma_0) -> c
~> forall c. (forall a. a -> a) -> (forall b. b) -&g
--avoid-reinstalls blindly or as a default flag is also
unfortunately not a good idea in general. There are simply too many
cases where installing older versions of packages (which is often the
only thing that helps) is not really the solution you want. That's
also the reason why it's no
at using
--force-reinstalls on Hackage might be an acceptable option, and it's
probably better than using --avoid-reinstalls by default. However, it
may still send the misleading message that a package "builds just
fine" when it practice it doesn't.
C
kill any
> performance, if needed.
There's
http://hackage.haskell.org/package/safeint/
It's not implemented quite as efficiently as it theoretically could
be, but it might do more or less what you want.
Cheers,
Andres
--
Andres Löh, Haskell Consultant
Well-Typed LLP, htt
ence.
Cheers,
Andres
--
Andres Löh, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com
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ink
there is or was a Haskell User Group as well, but it's currently
listed as "not active" on
http://www.haskell.org/haskellwiki/User_groups. Perhaps there's a
chance to bring it back to life?
Cheers,
Andres
--
Andres Lö
>>> Do you have any suggestions to install xmobar in this particular case?
>>
>> In case of executables I usually rm -rf ~/.ghc, cabal install,
>> and rm -rf ~/.ghc again. Executables are still here (in ~/.cabal/bin),
>> but all libraries are lost. Warning: it may break your development
>> environm
Hi Iavor.
> If you don't want to use the class system, you could write `repeat` with a
> type like this:
>
> repeat :: Proxy n -> a -> Vector n a
>
> (`Proxy` is the singleton family 'data Proxy n = Proxy`).
How is the polymorphism becoming any less parametric by using this
particular Proxy t
Hi Kazu.
> I'm now studying Trie in Okasaki's "Purely Functional Data Structure".
> Attached is the program in its appendix. I cannot understand how to
> use "empty", "look" and "bind". For instance, if I type 'look "" empty',
> I got an error:
>
>> look "" empty
> :2:1:
> No instance for (Fin
Hi Johan.
I haven't looked in detail at the overall problem, but:
> Flags chosen: base3=True, base4=True
>
> Why is Cabal setting both base3 and base4 to True?
This looks completely fine to me.
The Cabal .cabal file is stating:
if flag(base4) { build-depends: base >= 4 } else { build-depends
f What is anything but None:
> rewrite w (K1 x) | w /= None, Just val <- cast x = K1 val
> rewrite _ _ = K1 "NIL"
Does this help you?
(I'm attaching the full code.)
Cheers,
Andres
--
Andres Löh, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com
GRewrite
iginal "Decl". This works because on the
outside, no GADT pattern matches are involved, and within the type
class instances, the necessary type information is present.
This is certainly harder to understand than your original version. On
the other hand, it's
Hi Kazu.
I'd be surprised if zipWith' yields significant improvements. In the
case of foldl', the strictness affects an internal value (the
accumulator). However, in the case of zipWith', you're just forcing
the result a bit more, but I guess the "normal" use pattern of fibs is
that you want to se
> Well, it took a little bit of persuasion to let GHC not cache the list(s), but
> with
>
>
> fibs :: Int -> Integer
> fibs k = igo i !! k
> where
> i | k < 100 = 1
> | otherwise = 2
> igo :: Integer -> [Integer]
> igo i = let go = 0 : i : zipWith (+) go (tail go) in go
>
Hi John.
> What are the prospects for Haskell supporting Structured Graphs as defined
> here?
> http://www.cs.utexas.edu/~wcook/Drafts/2012/graphs.pdf
>
> Is there an interest by developers of GHC in doing this?
Could you be more specific about the kind of "support" you'd expect
from GHC? Basical
Hi.
> while playing with folds and trying to implement `!!` by folding, I came to
> the conclusion that:
>
> - `foldr` is unsuitable because it counts the elements from the end, while
> `!!` needs counting from the start (and it's not tail recursive).
What is the problem with the following defini
all" rather than "RankNTypes",
which indeed does not enable rank-n types, but only allows you to use
the "forall" syntax.
Cheers,
Andres
--
Andres Löh, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com
___
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tional packages that implement such functionality, though.
By using deepseq-generics, you can import Control.DeepSeq.Generics and
then define
> instance NFData Simple where rnf = genericRnf
Cheers,
Andres
--
Andres Löh, Haskell Consultant
Well-Typed LLP, http://
>> ghc is installed globally, and local packages should not "break" it.
>
> still cabal-install says so (and I don't dare to test ...)
If you're installing locally or (even better) in a sandbox, then you
cannot completely (i.e., irrevocably) break your compiler. You can
always remove the package d
"
So it's there, and even in the current Haskell Platform.
Cheers,
Andres
--
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Well-Typed LLP, http://www.well-typed.com
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e the code easier
to understand.
(And yes, I would be willing to be mentor for this project.)
Cheers,
Andres
--
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Well-Typed LLP, http://www.well-typed.com
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in = init $ \ nd0 -> do
> wd0 <- addWatch nd0 "foo"
> wd1 <- addWatch nd0 "bar"
> init $ \ nd1 -> do
> wd3 <- addWatch nd1 "baz"
> printInotifyDesc nd0
> printInotifyDesc nd1
> rmWatch nd0 wd0
> rmWatch nd1 wd3
> -
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