[erlang-questions] builtin regexp functions in Erlang/OTP R12B-3

Bjorn Gustavsson <>
Tue Jun 17 07:48:30 CEST 2008

Mats Cronqvist <> writes:

>   i think not allowing backreferences is the correct choice for erlang. 
> after all, erlang is about reliability. and it seems not being 
> POSIX-compliant has worked for 20 years.

Note that Patrik has implemented the re BIFs to be rescheduable,
meaning that even a badly written regular expression will not prevent
the emulator from running other Erlang processes (even in the non-SMP

As noted in the EEP, some regexp libraries would have been hard or
impossible to make rescheduable.

As far as we know, all previous interfaces to regexp libaries have
ignored the problem of blocking the emulator for the entire duration
of the regexp matching.  A badly written regexp would in those
implementations would indeed block the entire emulator while it was
executing (or one scheduler thread in the SMP emulator).

Björn Gustavsson, Erlang/OTP, Ericsson AB

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