It's worth noting that Go's regular expression engine doesn't aim to be compatible with Perl's (PCRE). Our implementation is aimed towards being compatible with re2. According to re2's documentation, \s is equivalent to: [\t\n\f\r ].

Okay that makes sense. Thanks for the quick response.

I think it'd be worth making that very obvious in the regexp docs (again, apologies if it already is and I missed it).

My uneducated view is that most golang users expect it be compatible with PCRE and are surprised when it is not.

I think it'd also be beneficial to the docs to list some of the special characters and their equivalencies, or include a link to the re2 syntax page.

This is documented at https://golang.org/pkg/regexp/syntax.

Hey thanks for that. Below is the first paragraph in the regexp docs: https://golang.org/pkg/regexp/

Package regexp implements regular expression search.

The syntax of the regular expressions accepted is the same general syntax
used by Perl, Python, and other languages. More precisely, it is the syntax 
accepted by RE2 and described at https://golang.org/s/re2syntax, except
for \C. For an overview of the syntax, run...

Given this thread, I think this is a bit misleading. It should read:

The syntax of the regular expressions accepted is the syntax prescribed by RE2
and described at https://golang.org/s/re2syntax, except for \C.

This syntax largely conforms with the syntax used by Perl, Python, and other
languages, but there are some subtle differences, so please check the syntax docs.

@ianlancetaylor - please consider this change. I think it'd be helpful to make this a little more explicit.

I reopened the issue. Want to send a change?

Sure will do. Thank you!

It seems weird to me that the first thing the Go regexp documentation does is link to another project, i.e., the docs for the C++ RE2 syntax. Could we link to Go documentation -- https://golang.org/pkg/regexp/syntax/ -- instead?

    This package uses RE2 syntax for regular expressions. Users of regular
    expressions in Perl, Python, and other languages and tools will find it
    familiar. For an overview of the syntax, see

        https://golang.org/pkg/regexp/syntax/

    Or run

        go doc regexp/syntax

@benhoyt Do you like this wording? Forgive me if @Jarch09 has already submitted a change.

@qbradq I like that wording, yes.

Change https://golang.org/cl/243399 mentions this issue: regexp: link to the regexp syntax documentation from go doc regexp