[Haskell-cafe] book "Haskell Data Analysis Cookbook" by Nishant Shukla

[Tobias Dammers]

It is not the same thing, really, unless I'm misunderstanding. AFAIK there
is no straightforward way of making the combined check-if-exists-and-delete
block atomic at the bearsden level, even if you force serial execution at
the haskell level, and the established solution is to forgo the existence
check altogether, relying on the delete call to throw when the file doesn't
exist.
On Jul 13, 2014 2:32 AM, "Vasili I. Galchin" <vigalchin at gmail.com> wrote:

> that was exactly my point ... I.e. if  between two lines the "Haskell
> thread-of-execution" is interrupted ... and another thread/process ...
> .deletes the file then 2nd "line" of code would cause an exception to
> be thrown ... i.e. because of non-existence .. . Brandon, aren't we
> saying the same thing ... if so, forgive, my English  .. :-)
>
> Vasya
>
> On Sat, Jul 12, 2014 at 7:02 PM, Brandon Allbery <allbery.b at gmail.com>
> wrote:
> > On Sat, Jul 12, 2014 at 7:54 PM, Vasili I. Galchin <vigalchin at gmail.com>
> > wrote:
> >>
> >> --  these two lines are non-thread safe     .. yes?? to be thread-safe
> >> the  above line and the following line would have to be together
> >> atomic ....
> >
> >
> > Not even then would it really be safe; it should trap the exception from
> > readFile failing, instead of checking existence in a separate step.
> >
> > --
> > brandon s allbery kf8nh                               sine nomine
> associates
> > allbery.b at gmail.com
> ballbery at sinenomine.net
> > unix, openafs, kerberos, infrastructure, xmonad
> http://sinenomine.net
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