[erlang-questions] '--' BIF to be used with caution?

Malcolm Dowse <>
Thu Feb 5 15:30:02 CET 2009


>
> > The unresponsiveness seems to be caused by '--' being a BIF. Is there a
> good
> > reason for making it a BIF if it's not always an improvement?
>
> I suppose it is a BIF because it is an operator (although that is not
> strictly necessary).
> Nowadays we always make new BIFs non-blocking ("trapping" as we call it) if
> they
> can run for a long time, but we usually only fix old BIFs if there is
> a real problem in a real
> application.
>
> I have added a warning note to the reference manual and to the
> documentation
> for lists:subtract/2. (Will appear in R13A.)


I don't mind too much if '--' remains O(N^2). But the fact that it made ERTS
unresponsive is more of a worry, to me, because this seemed to go against
the spirit of the language. I my case, I knew that my algorithm was fairly
brutal, but I thought to myself "Ah, it will only take a few minutes, and
I'll execute it in a background process, so it will be OK".

Personally, I have no problem with this being left as a "known issue" for
the time being. But maybe that's just because I now know about it. :-)

Malcolm


>
>
> /Bjorn
>
> --
> Björn Gustavsson, Erlang/OTP, Ericsson AB
>
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