Sounds exciting!
On Tue, Jun 5, 2012 at 6:22 PM, Bartosz Milewski wrote:
> You might have seen a few post by me mentioning FP Complete and asked
> yourself the question: Who is this guy and what is FP Complete?
>
> I haven't been active in the Haskell community, as I'm a relative newcomer
> to Ha
> newtype Q p a = Q (p a -> a)
>
> instance ContraFunctor p => Functor (Q p) where
> fmap h (Q w) = Q (h . w . cmap h)
using "cmap" for contravariant map. For instance, p a = u -> a.
> instance ContraFunctor p => Applicative (Q p) where
> pure a = Q (pure a)
> Q fs <*> Q as = Q (\ r ->
>
Welcome to the community Bartosz.
-- Johan
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You might have seen a few post by me mentioning FP Complete and asked
yourself the question: Who is this guy and what is FP Complete?
I haven't been active in the Haskell community, as I'm a relative
newcomer to Haskell. I am better known in the C++ community where I've
been promoting function
Hi Haskell Cafe!
To develop Haskell-Type-Exts (HTE) [1,2], I need to have typing judgments
for each language construct in Haskell 2010 with two extensions: RankNTypes
and local assumptions (GADTs, Type Functions and etc). Since I could not
find any academic paper describing a type system supportin
Hi Everyone,
I'm happy to announce version 0.3.5.2[1] of the cereal serialization
library. This is a bugfix release, mostly improving performance
characteristics of the library. One noteable change is with runGetLazy,
which will now perform as expected when a parser attempts to consume
more
Hi all,
when I reported a typechecker performance problem related to functional
dependencies
http://hackage.haskell.org/trac/ghc/ticket/5970
I promised to try to convert from functional dependencies to type
families.
Thus I converted my code and the llvm package to type-families:
htt
As far as I'm aware:
- property-based testing wasn't new (think 'assertions' and then
think 'branch coverage')
- randomly generated test cases weren't new (look up 'fuzz testing')
and there were tools like DGL to generate random test cases in a
controlled sort of way
+ the *type-driven*
On Jun 5, 2012, at 10:51 AM, Bryan O'Sullivan wrote:
> On Tue, Jun 5, 2012 at 9:12 AM, Warren Harris
> wrote:
>
> which helps in many cases, but for some the parsing seems bi-stable,
> alternating between two imprecise double values and causing the test to fail.
> I was wondering if anyone c
On Tue, Jun 5, 2012 at 10:51 AM, Bryan O'Sullivan wrote:
> If you need the full precision, use rational instead. The double parser is
> there because parsing floating point numbers is often a bottleneck, and
> double intentionally trades speed for precision.
Relevant code in
https://github.com/bo
On 5 June 2012 18:46, Gábor Lehel wrote:
> I must be missing something, but this seems a bit useless to me. You
> have a phantom type parameter on Proxy, and then you're hiding it. So
> when you pattern match on ProxyWrapper you recover the fact that there
> was a type which satisfies the constrai
On Tue, Jun 5, 2012 at 9:12 AM, Warren Harris wrote:
>
> which helps in many cases, but for some the parsing seems bi-stable,
> alternating between two imprecise double values and causing the test to
> fail. I was wondering if anyone could suggest a better work-around for this
> problem, or explai
On Jun 5, 2012, at 9:57 AM, Johan Tibell wrote:
> I don't think applying == to something that contains floating point
> values at the leaves makes much sense. You want some approxEq function
> that uses approximate equality on floating point value or you want to
> equality function that ignores t
On Tue, Jun 5, 2012 at 4:28 AM, Ketil Malde wrote:
> Rogan Creswick writes:
>
>>> I have a small project that installs a couple of Haskell tools and a
>>> script that uses these. Cabal will of course build and install the
>>> Haskell programs, but how can I get Cabal to install the script as
>>>
On Tue, Jun 5, 2012 at 9:51 AM, Warren Harris wrote:
>
> On Jun 5, 2012, at 9:38 AM, Johan Tibell wrote:
>> You want to perform your test as
>>
>> d1 - d2 < epsilon
>
> What's the best way to do this though, since aeson's Value type already
> provides instance Eq? I guess I can write my own su
On Jun 5, 2012, at 9:38 AM, Johan Tibell wrote:
> You want to perform your test as
>
>d1 - d2 < epsilon
What's the best way to do this though, since aeson's Value type already
provides instance Eq? I guess I can write my own suite of equality comparisons,
but these aeson values are the lea
On Tue, Jun 5, 2012 at 5:29 PM, Bas van Dijk wrote:
> Hello,
>
> I have the following program:
>
> --
> {-# LANGUAGE ConstraintKinds #-}
> {-# LANGUAGE ExistentialQuantification #-}
> {-# LANGUAGE ScopedTypeVariables #-}
>
> i
On Tue, Jun 5, 2012 at 9:12 AM, Warren Harris wrote:
> which helps in many cases, but for some the parsing seems bi-stable,
> alternating between two imprecise double values and causing the test to fail.
You want to perform your test as
d1 - d2 < epsilon
where epsilon is derived from the r
What you want seems a bit tricky.
> p :: ProxyWrapper Num
> p = ProxyWrapper (Proxy :: Proxy Int)
At this point, all you know about p is that it is a Num. You don't
know that it is Typeable, because you choose to forget about that. You
could give p the type 'ProxyWrapper (Ext Typeable Num)' and i
On 5 June 2012 17:57, Bas van Dijk wrote:
> It works.
It turns out it doesn't work exactly as I want. Say I have this
ProxyWrapper of Nums:
p :: ProxyWrapper Num
p = ProxyWrapper (Proxy :: Proxy Int)
then the following would give a type error:
oops :: TypeRep
oops = typeOfInnerProxy p
Cou
The double parser provided by Data.Attoparsec.ByteString.Char8 looses precision
around the 13-15th decimal place
(http://hackage.haskell.org/packages/archive/attoparsec/0.10.2.0/doc/html/Data-Attoparsec-ByteString-Char8.html#v:double).
Unfortunately this reeks havoc with my attempts to write a q
As Brent said, each version of GHC needs to build its own copy of the
packages you use in your projects. Conveniently, these are all kept in
separate directories by GHC version, so you can leave your old ones around
as you compile new ones with the new platform.
However...
Most users don't want m
On 5 June 2012 17:52, Andres Löh wrote:
> Hi Bas.
>
> I haven't thought about this for long, but ...
>
>> data ProxyWrapper constraint =
>> forall a. constraint a => ProxyWrapper (Proxy a)
>
> I'm assuming adding Typable a in ProxyWrapper is not an option for you?
No, I would rather keep that
Hi Bas.
I haven't thought about this for long, but ...
> data ProxyWrapper constraint =
> forall a. constraint a => ProxyWrapper (Proxy a)
I'm assuming adding Typable a in ProxyWrapper is not an option for you?
So then what about:
class (c1 a, c2 a) => Ext c1 c2 a
instance (c1 a, c2 a) => E
Hello,
I have the following program:
--
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE ScopedTypeVariables #-}
import Data.Proxy (Proxy)
import Data.Typeable (Typeable, TypeRep, type
I spent quite some time going through the cabal docs to generate some
files automatically with hails. I totally feel your pain :)
What I'm going to suggest is not really a solution to your problem,
but since modifying the hooks to install specific programs is not the
best solution either, you migh
Hi Cafe,
I'm pleased to announce that HQuantLib has been released recently after a year
of sleep. This is mainly a technical release to clean up dependencies and
refresh build infrastructure.
The library is intended to be a functional port of QuantLib
(http://quantlib.org), a free/open-source
On Tue, Jun 5, 2012 at 4:18 AM, Etienne Laurin wrote:
>
> Thanks for the idea. Here it is.
>
> http://hackage.haskell.org/trac/ghc/wiki/TFvsFD
>
> I posted my comments on the matter along with many additional comments
> and examples that I found.
>
Thanks!
One part is confusing me.
In the secti
Very useful to get a gadt back to monotype without an existential, which
would mean to use classes for future uses of it with its load of object
oriented thinking.
Thanks for sharing.
paolino
2012/6/4 Ryan Ingram
> Another option is to reify the type so that you can get it back somehow.
> Here
Rogan Creswick writes:
>> I have a small project that installs a couple of Haskell tools and a
>> script that uses these. Cabal will of course build and install the
>> Haskell programs, but how can I get Cabal to install the script as
>> well? There's a host of UserHooks available¹, but it'd prob
On Tue, Jun 5, 2012 at 5:12 PM, Ivan Perez wrote:
> This is a known issue ([1]), and my guess, according to [2], is that
> it is fixed in the latest version ([3]), which has not been uploaded
> to hackage yet.
>
> What happens if you install gtk from that repo instead? You may want
> to try to ap
This is a known issue ([1]), and my guess, according to [2], is that
it is fixed in the latest version ([3]), which has not been uploaded
to hackage yet.
What happens if you install gtk from that repo instead? You may want
to try to apply the patch to the version of gtk2hs that is available
on hac
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