Should we have primitive fill-once variables?

[Joachim Breitner]

Hi,

Am Freitag, den 29.06.2018, 12:54 -0400 schrieb David Feuer:
> On Friday, June 29, 2018 11:51:07 AM EDT Joachim Breitner wrote:
> > when reading the subject I was expecting something like this:
> > 
> >    -- | pure! but blocks until the IVar is written
> >    readIVar :: IVar a -> a 
> > 
> >    -- | tries to write to an IVar. 
> >    -- Succeeds if it is empty (returning True)
> >    -- Does nothing if it has been written to (returning False)
> >    writeIVar :: IVar a -> a -> IO Bool
> 
> It really depends. Are there useful (compile-time or run-time)
> optimization for IVars (write-once) that don't apply to QVars (fill-
> once)? If so, we might indeed want to offer writeIVar as you suggest,
> and

I don’t know! Maybe the GC can treat a filled IVar differently (because
it is no longer mutable?) But really, I don't know :-)

Cheers,
Joachim
-- 
Joachim Breitner
  mail at joachim-breitner.de
  http://www.joachim-breitner.de/
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