This module allows you to override the behavior of the smart match operator
("~~"). "use smartmatch $matcher" hooks into the compiler to replace the
smartmatch opcode with a call to a custom subroutine, specified either as
a coderef or as a string, which will have "smartmatch::engine::" prepended to
it and used as the name of a package in which to find a subroutine named
"match". The subroutine will be called with two arguments, the values on the
left and right sides of the smart match operator, and should return the
result.
