This documents count(). This function only works when used like this @map[key] = count(); But it is implemented and works. If used differently you get a syntax error which is not helpful. This is why I chose to document it like this. Another option would be to document the language (so it is clear where it is possible to use what).
max(), min() and sum() are other functions that behave like this. Their documentation should also be adjusted IMO. -- :wq Claudio Index: bt.5 =================================================================== RCS file: /cvs/src/usr.sbin/btrace/bt.5,v retrieving revision 1.13 diff -u -p -r1.13 bt.5 --- bt.5 12 Nov 2021 16:57:24 -0000 1.13 +++ bt.5 16 Nov 2021 09:50:52 -0000 @@ -120,6 +120,11 @@ Functions: .It Fn clear "@map" Delete all (key, value) pairs from .Va @map . +.It "@map[key]" = Fn count +Increment the value of +.Va key +from +.Va @map . .It Fn delete "@map[key]" Delete the pair indexed by .Va key