from your keyboard and onto a mountain
bike) and an experienced management team with a proven track-record.
We are looking for developers to be based in London and Exeter.
--
Ben Moseley - Programmer
b...@benmoseley.net
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Haskell
, 2012 at 09:34:35AM +, Ben Moseley wrote:
Consider the code below:
{-# LANGUAGE Arrows,Rank2Types #-}
import Control.Arrow
-- cmdcomb :: Arrow a = (a (env,x) x) - a (env,x) x
-- cmdcomb aegg = aegg
cmdcomb :: Arrow a = (forall x . a (env,x) x) - a (env,x) x
cmdcomb aegg
Yes, indeed.
Thanks again, (and thanks for building all the arrow notation infrastructure in
the first place - it's awesome!)
--Ben
On 15 Jan 2012, at 11:57, Ross Paterson wrote:
On Sun, Jan 15, 2012 at 11:42:28AM +, Ben Moseley wrote:
The real application is trying to process
The following code seems to trigger a panic (under 7.03, 7.2 and 7.4):
{-# LANGUAGE Arrows, GADTs #-}
import Control.Arrow
data Value a where BoolVal :: Value Bool
class ArrowInit f where
arrif :: f b - ()
instance ArrowInit Value where
arrif = proc BoolVal - returnA - () -- this
On 7 Mar 2011, at 23:38, Alexander Solla wrote:
_|_ /= (_|_,_|_)
(undefined, undefined)
(*** Exception: Prelude.undefined
That is as close to Haskell-equality as you can get for a proto-value that
does not have an Eq instance. As a consequence of referential transparency,
It looks to me as though that wouldn't be expected to work because 'a' and 't'
are different type variables... which seems to be essentially what the error
msg is saying...
...am I missing something?
--Ben
On 17 Aug 2010, at 19:54, Dan Knapp wrote:
Below, please find a snippet from a
that happens...
--Ben
On 17 Aug 2010, at 20:04, Ben Moseley wrote:
It looks to me as though that wouldn't be expected to work because 'a' and
't' are different type variables... which seems to be essentially what the
error msg is saying...
...am I missing something?
--Ben
On 17 Aug
it's clear that FP ideas are becoming mainstream
_without_ any need of help from the financial community
This is far from clear - unless you want to deny that the financial community
has had any impact on FP...
due to Objective C with its Smalltalk influence
...and it's interesting to
Investment banking isn't likely to lead to improvements in zygohistomorphic
prepromorphisms.
Given that an investment bank could (purely hypothetically of course ;-)
use - say - paramorphisms as their fundamental approach to processing a
deeply-embedded DSEL, I wouldn't be too quick to
I expect we can - we'll investigate.
--Ben
On 2 Nov 2009, at 09:32, Simon Peyton-Jones wrote:
| Is there any difference between -XImpredicativePolymorphism and -
| XImpredicativeTypes?
No there isn't. There's only one flag, -XImpredicativeTypes.
| Hyena uses the latter, and we're using
Is there any difference between -XImpredicativePolymorphism and -
XImpredicativeTypes?
Hyena uses the latter, and we're using Hyena somewhat in anger.
--Ben
On 30 Oct 2009, at 09:51, Simon Peyton-Jones wrote:
Friends
One more update about GHC 6.12, concerning impredicative polymorphism.
Or for a bit of variety:
selectPlus s = [cs | ('+':cs) - lines s]
--Ben
On 4 Sep 2009, at 20:40, Martijn van Steenbergen wrote:
Hi Serge,
Serge LE HUITOUZE wrote:
I'm asking some advice on a small piece of code representing a
simplified version of a treatment I need to perform.
I have a
Unfortunately, this isn't supported at present.
--Ben
On 14 Apr 2009, at 05:28, Norman Ramsey wrote:
I've got a fairly large GADT for which I wished to use
deriving (Show)
but I got a mysterious error message:
Exp.hs:13:11:
Can't make a derived instance of `Show (Exp a)'
(`Exp' has
On 31 Jan 2009, at 20:54, Gregg Reynolds wrote:
On Sat, Jan 31, 2009 at 1:02 PM, Ben Moseley ben_mose...@mac.com
wrote:
You can view a polymorphic unary type constructor of type :: a -
T as a
polymorphic function.
Shouldn't that be * :: a - T a ?
Yes, you're right. And when I say
You can view a polymorphic unary type constructor of type :: a - T
as a polymorphic function.
In general, polymorphic functions correspond roughly to natural
transformations (in this case from the identity functor to T).
--Ben
On 31 Jan 2009, at 17:00, Gregg Reynolds wrote:
Hi,
I think
there are similar
scenarios on which I've already given up in despair, such as
writing a
generator for creating well-typed terms in a nontrivial language.
This is something I've also struggled with. I'm coming to the
conclusion that it'd really be useful for the Gen monad to be
You mentioned a dream
Have you looked at Yi? might be worth a peek if you're prepared
to work towards your dream.
http://www.haskell.org/haskellwiki/Yi
...a long way to go - but it certainly nails #7!
--Ben
On 21 May 2007, at 15:44, Leif Frenzel wrote:
Bayley, Alistair wrote:
Has anyone succeeded in getting it running on OSX/intel at all?
...I had a brief go a few weeks back, managed to get the Cairo Clock
running, but anything that used GTK seemed to blow up instantly. (OSX/
ppc was fine).
--Ben
On 13 Nov 2006, at 19:03, Duncan Coutts wrote:
On Mon,
gtk-demo seemed to run fine.
--Ben
On 13 Nov 2006, at 21:01, Duncan Coutts wrote:
On Mon, 2006-11-13 at 20:49 +, Ben Moseley wrote:
Has anyone succeeded in getting it running on OSX/intel at all?
I'm not sure actually. I seem to recall someone trying it but I can't
remember who now
Hi,
Just thought I'd send out a quick mail to see if there are any other
Haskellers based in London who might be interested in getting
together occasionally.
Anyway, if you're interested please reply to this.
Cheers,
--Ben
___
Haskell-Cafe
Simon Peyton-Jones simonpj at microsoft.com writes:
... And avoid
getting screwed up by malicious folk?
Probably the biggest example of this type of thing working well on
a large scale is Wikipedia. I'm not intimately familiar with the process
they use, but I believe there are a number of
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