Hi, On Thu, Nov 10, 2022 at 11:39 AM Tobias Geerinckx-Rice <m...@tobias.gr> wrote: > > ‘By default, Guile supports POSIX extended regular expressions.’ —
Yes, the word "extended" is often omitted. A good summary is here. [1] POSIX adopted some, but not all, of the Perl Compatible Regular Expressions (PCRE), which are more powerful but older. From the 'grep' manual page (see the -E switch): "In basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their special meaning". Kind regards Felix Lechner [1] https://en.wikibooks.org/wiki/Regular_Expressions/POSIX-Extended_Regular_Expressions