On 30 Nov 2004, at 23:29, Ben Rudiak-Gould wrote:
Jules Bean wrote:
However, your problem *does* have a natural underlying monad, if you
care to use it.
I may be confused, but I don't think it does. It seems like the OP
wants a type like
data Perhaps a = Success a | Failure [Error]
[snip]
I
On 1 Dec 2004, at 00:37, Marcin 'Qrczak' Kowalczyk wrote:
Ben Rudiak-Gould [EMAIL PROTECTED] writes:
I may be confused, but I don't think it does. It seems like the OP
wants a type like
data Perhaps a = Success a | Failure [Error]
When writing a compiler, it makes sense to collect errors as by
[EMAIL PROTECTED] wrote:
That is too pessimistic, I'm afraid. There is also an intensional
equality. Granted, it can be sound but never, in general, complete
(although it can be total). That is, if the comparison function
returns True, then the arguments truly denote the same, identically the
same
On Tue, 30 Nov 2004 18:36:46 + (UTC), Pavel Zolnikov
[EMAIL PROTECTED] wrote:
[..]
type M2 a = OuptutMonadT Maybe String a
whenError:: M2 a - M2 a - M2 a
1 foo a b = do
2 output before
3 let r = liftM2 (+) a b
4 `whenError` $ reportError error
5 return r
Jules Bean [EMAIL PROTECTED] writes:
When writing a compiler, it makes sense to collect errors as by the
writer monad, and not abort anything - producing dummy values instead
(except perhaps some fatal errors when it's inconvenient).
Or you could use the monad:
data Perhaps a = Success a |
On Tuesday 30 Nov 2004 3:02 pm, Lennart Augustsson wrote:
I reiterate: not even device drivers written in C use TWIs.
(Well, at least not quality drivers. :))
A finite pool of N devices is still a unique resource.
Ultimately you have to contain the problem locally with a modular
solution, or
Adrian Hey wrote:
On Tuesday 30 Nov 2004 3:02 pm, Lennart Augustsson wrote:
I reiterate: not even device drivers written in C use TWIs.
(Well, at least not quality drivers. :))
A finite pool of N devices is still a unique resource.
Ultimately you have to contain the problem locally with a
On Tuesday 30 Nov 2004 4:01 pm, Simon Peyton-Jones wrote:
(d) I'm not averse to changing GHC in some way, but big changes (e.g top
level -) would need a jolly persuasive argument and solid consensus.
Smaller changes (e.g. a robust promise about top-level newMVars) are
easier of course.
(e)
On Wednesday 01 Dec 2004 12:07 pm, Lennart Augustsson wrote:
Adrian Hey wrote:
It's not a language issue. It's a design issue. And in the case
of device drivers you do want to pass the buck up to the layer
that handles device drivers. Having each driver keep it's own
global state is just
Actually I now think that not only are top level TWIs okay, I can
get extra contexts by rewriting the MVar module. Here I can
create a TWI in the new MVar module called context, and all
mvar writes and reads would be parameterised by context. In
this way I can change the context then call oneShot
Hi,
Just out of curiosity (I cannot come up with a practical example): Why
doesn't the following piece of code type check in GHC (with
extensions)?
foo :: (forall a . (Eq a) = a) - Integer
foo = undefined
It seems like the type-class constraint is playing a decisive rôle
here, since the
Hi,
foo _ = undefined
works fine.
Otherwise the poor little a has no chance to get disambiguated.
... Ambiguous type variable `a' in the top-level constraint ...
Ralf
Stefan Holdermans wrote:
Hi,
Just out of curiosity (I cannot come up with a practical example):
Why doesn't the following piece
Hello,
I'm trying to make work the following code (I'm using GHCi
with flags -fglasgow-exts -fallow-undecidable-instances):
infixl 6 :+, :-
infixl 6 .+, .-
data TMyExpr = TMyExpr :+ TMyExpr
| TMyExpr :- TMyExpr
| Val Int
| Id String
class MkExpr a b where
(.+)
On Wed, 1 Dec 2004, Dusan Kolar wrote:
Hello,
I'm trying to make work the following code (I'm using GHCi
with flags -fglasgow-exts -fallow-undecidable-instances):
infixl 6 :+, :-
infixl 6 .+, .-
data TMyExpr = TMyExpr :+ TMyExpr
| TMyExpr :- TMyExpr
|
I put up a wiki page summarizing the main proposals for top-level
mutable state. The type-dictionary approach isn't there yet, but there's
a space for it; I'll probably fill it in within the next 24 hours unless
someone else feels like doing it first.
Please add more detail, objections,
On Wednesday 01 Dec 2004 6:29 pm, Ben Rudiak-Gould wrote:
I put up a wiki page summarizing the main proposals for top-level
mutable state. The type-dictionary approach isn't there yet, but there's
a space for it; I'll probably fill it in within the next 24 hours unless
someone else feels like
On 2004-11-30, GoldPython [EMAIL PROTECTED] wrote:
Has anyone tried presenting the language to the average rank and file
programming community? If so, was it successful? If not, is there
interest in doing so?
I am very interested in doing that.
I'm a relatively recent Haskeller. I come from
On 1 Dec 2004, at 18:29, Ben Rudiak-Gould wrote:
Here's the page:
http://haskell.org/hawiki/GlobalMutableState
Nice summary.
What I think is missing is an explanation of when you would want this
feature (and when you wouldn't, more importantly). Here is the kind of
platonic dialogue that
Using ghci, I am getting this error message:
*Main timeOp $ print $ sizeFM bigFM'
GHC's heap exhausted: current limit is 268435456 bytes;
From this code:
makeList x = map ((\x-x `mod` range).abs) $
Random.randoms (Random.mkStdGen x)::[Int]
range=10
On Wednesday 01 December 2004 21:18, John Goerzen wrote:
I also have a very small start on a haskell for hackers (hackers in
the non-evil sense) sort of document. One this doesn't ignore I/O as
hard or unimportant. I/O in Haskell doesn't suck.
I come from a similar area (large control
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