Welcome to issue 188 of the HWN, a newsletter covering developments in
the Haskell community. This release covers the week of June 19 to
25, 2011.
It was brought up in cafe this week that some would prefer to see
full links in the text version of the mailing list as opposed to the
Derp, forgot to CC the Cafe.
Which ones have you read already? It's difficult to make recommendations
without knowing what's already off the table.
Additionally, don't be put off if it takes a lot of effort to figure anything
out. Math textbooks and so on are unlike any other textbook. It's n
Thank you very much, this worked.
On 06/30/2011 12:03 AM, aditya siram wrote:
> Try enabling OverlappingInstances extension by adding this to the top
> of the file:
> {-# LANGUAGE OverlappingInstances #-}
>
> -deech
>
> On Wed, Jun 29, 2011 at 4:50 PM, Philipp Schneider
> wrote:
>> Hi cafe,
>>
>>
On Wed, Jun 29, 2011 at 7:11 PM, Gracjan Polak wrote:
> Proper way to handle this is probably to add additional Bool parameter to
> mkFD,
> fdToHandle and GHC.IO.FD.openFile that says if Report's semantics should be
> held
> or not. Then openFileShared can be build on top of that.
>
> (Possibly
Gracjan Polak gmail.com> writes:
>
> I'm looking for file locking code in GHC.IO.* modules, but cannot find any.
>
Just for the record: locking code resides in GHC.IO.FD in mkFD which calls
lockFile.
There is a heavy machinery underneath that is working hard to ensure Report's
semantics. Someb
Hi Philipp,
On 06/29/2011 11:50 PM, Philipp Schneider wrote:
Hi cafe,
in my program i use a monad of the following type
newtype M a = M (State -> (a, State))
btw., it looks like you just rebuilt the State monad.
...
instance (Show a,Show b) => Show (M (a,b)) where
show (M f) = let
Try enabling OverlappingInstances extension by adding this to the top
of the file:
{-# LANGUAGE OverlappingInstances #-}
-deech
On Wed, Jun 29, 2011 at 4:50 PM, Philipp Schneider
wrote:
> Hi cafe,
>
> in my program i use a monad of the following type
>
> newtype M a = M (State -> (a, State))
>
>
Hi cafe,
in my program i use a monad of the following type
newtype M a = M (State -> (a, State))
i use the monad in two different ways. The type variable "a" can be a
pair as in
interp :: Term -> Environment -> M (Value,Environment)
and it can be just a value as in
type Environment = [(Name,
At Wed, 29 Jun 2011 21:13:47 +1000,
John Ky wrote:
>
> Hi Haskell Cafe,
>
> I've written an echo server using just sockets:
>
> ...
>
> When I send text to it, it will echo it back immediately after my newline.
>
> I then modified it to user IterIO:
>
> import Control.Concurrent
> imp
Hi all,
Has anyone managed to get hmatrix-static to compile with ghc 7.0.2,
and if so would you be willing to share a patch?
With best wishes,
Anand
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On Wed, Jun 29, 2011 at 4:16 AM, Roman Leshchinskiy
wrote:
> Gregory Collins wrote:
>> For an example of a similar technique (minus the freezing part), I did
>> a similar thing in the hashtables library:
>
> You might be interested in 'grow' :-)
I would be, except to save a couple of words I use
Hi Haskell Cafe,
I've written an echo server using just sockets:
import Control.Concurrent
import Control.Exception
import Control.Monad
import Network
import Offsync.Data
import System.IO
import System.IO.Error (isEOFError)
main = withSocketsDo $ do
sListen <- listenOn (PortNumber 8000)
put
Max Bolingbroke hotmail.com> writes:
>
http://hackage.haskell.org/packages/archive/unix/2.4.2.0/doc/html/System-Posix-IO.html.
Thanks for the link. I tried to use it:
Prelude System.Posix.IO> fd1 <- openFd "xxx.tmp" WriteOnly (Just 0666)
defaultFileFlags
Loading package unix-2.4.0.2 ... linking
On Wednesday 29 June 2011, 11:37:39, Yitzchak Gale wrote:
>
> So it's the derived Read instance in this context that
> is causing the problem. Here is a slightly smaller test
> case that triggers the bug:
>
> {-# LANGUAGE MultiParamTypeClasses, UndecidableInstances #-}
> module Bug where
> class
Daniel Fischer wrote:
> No, the instance head is just a type variable, not a type constructor
> applied to type variables
Oops, you're right. GHC was telling the truth, I should have
paid closer attention!
Fixing my minimal example, I get:
{-# LANGUAGE MultiParamTypeClasses, UndecidableInstances
On Wednesday 29 June 2011, 10:22:20, Yitzchak Gale wrote:
> Ryan Ingram wrote:
> > So this is definitely a GHC bug, but I think the problem is probably
> > triggered by this line:
> >
> > instance Serializable a b => IResource a
> >
> > I don't think this is a valid instance declaration without
http://hackage.haskell.org/trac/ghc/ticket/5287
El 29/06/2011 10:22, "Yitzchak Gale" escribió:
> Ryan Ingram wrote:
>> So this is definitely a GHC bug, but I think the problem is probably
>> triggered by this line:
>>
>> instance Serializable a b => IResource a
>>
>> I don't think this is a valid
Ryan Ingram wrote:
> So this is definitely a GHC bug, but I think the problem is probably
> triggered by this line:
>
> instance Serializable a b => IResource a
>
> I don't think this is a valid instance declaration without a functional
> dependency on Serializable, as it's impossible to know whic
Gregory Collins wrote:
> On Tue, Jun 28, 2011 at 6:20 PM, Eric Rasmussen
> wrote:
>
>> It runs quickly, but I naively thought I could outperform it by
>> reworking "many" to build a vector directly, instead of having to build
>> a list first and then convert it to a vector:
>>
>> manyVec :: Altern
Ryan'
P robably the read instance can not be infered without the functional
dependency but the bug is also triggered with it. I simplified ithe coder as
much as possible
El 29/06/2011 02:26, "Ryan Ingram" escribió:
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Hi David,
Good point. Not too fussed, though now that I think about it, I would have
preferred it if enumFile' was defined in the tutorial rather than in the
module.
Cheers,
-John
On 29 June 2011 13:53, wrote:
> At Wed, 29 Jun 2011 10:11:26 +1000,
> John Ky wrote:
> >
> > [1 ]
> > [1.1 ]
>
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