> The logical dual to tryTakeMVar would be
>tryPutMVar :: MVar a -> a -> IO Bool
tryPutMVar :: MVar a -> a -> IO Bool
tryPutMVar m a
= Exception.catchAllIO
(do { putMVar m a; return True })
(\e -> case e of
PutFullMVar -> ret
Simon Marlow wrote:
> The only way I can see to do this is to add a lock field to the MVar. And
> since this lock would look very much like another MVar, you may as well just
> use another MVar to lock it (after all, that adds exactly zero extra
> complication to the system :-).
Absolutely.
> The
> Marcin 'Qrczak' Kowalczyk wrote:
> > MVars should be simple. They are building blocks for more complex
> > things.
> I completely agree. But _if_ it should happen that my proposal could
> be implemented without making anything else more complicated,
> it would be
> the most logical new primiti
This seems pretty sensible to us. We'll try it.
Simon
| -Original Message-
| From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
| Sent: 08 April 2000 20:44
| To: [EMAIL PROTECTED]
| Subject: tryTakeMVar :: MVar a -> IO (Maybe a)
|
|
| Wouldn't be nice to have such fun
Marcin 'Qrczak' Kowalczyk wrote:
> MVars should be simple. They are building blocks for more complex
> things.
I completely agree. But _if_ it should happen that my proposal could
be implemented without making anything else more complicated, it would be
the most logical new primitive. If not, th
Mon, 10 Apr 2000 10:50:35 +0200, George Russell <[EMAIL PROTECTED]> pisze:
> Would it be possible to implement an operation to lock an MVar
> without any extra expense? So that the thread owning the MVar can
> do things to it, but no other thread can.
What does "lock" mean? takeMVar is a kind o
Would it be possible to implement an operation to lock an MVar without
any extra expense? So that the thread owning the MVar can do things to
it, but no other thread can. If it is possible, I suggest that it be
added and it would solve Marcin's problem (isEmptyMVar would then suffice).
10 Apr 2000 05:46:31 GMT, Marcin 'Qrczak' Kowalczyk <[EMAIL PROTECTED]> pisze:
> (but tryTakeMVar would suffice for isEmptyMVar).
Well, not exactly.
--
__("$ P+++ L++>$
Sun, 9 Apr 2000 13:54:47 -0700, Sigbjorn Finne <[EMAIL PROTECTED]> pisze:
> > Wouldn't be nice to have such function?
>
> Have you tried using Concurrent.isEmptyMVar ?
isEmptyMVar is not enough to implement tryTakeMVar (but tryTakeMVar
would suffice for isEmptyMVar). Just after checking that it
>
> Wouldn't be nice to have such function?
>
Have you tried using Concurrent.isEmptyMVar ?
--sigbjorn
>
Wouldn't be nice to have such function?
I wanted to translate a thread example written in Ruby and realized
that it's impossible to write that function using MVar primitives
provided; and no module seems to provide an equivalent using
another kind of concurrent variable. I had to simulate mutexes
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