= ~
is two operators: assignment and bitwise negation. Seeing as it is followed by a regex substitution it is likely that you have confused it with =~
, which is the binding operator, used with regexes (among other things).
Assuming that = ~
is a typo, the map
statement simply applies a regex substitution s///
to a list of strings, changing 2-3 numbers (e.g. 12
or 123
) to A
. It is written somewhat redundantly, and can be reduced to
s/\d{2,3}/A/ for @GradeA;