MooseX::Types::Signal exports a type, Signal, that recognizes valid signals
on your platform. The underlying type is a non-negative number, but there is
a coercion from strings to numbers that recognizes signals by name.

There are also more restrictive types, PerlSignal and UnixSignal. UnixSignal
only understands signals that are in your system's signal.h header file.
PerlSignal only understands signals that are in Perl's %Config hash. Signal
is either/or, with preference to UnixSignal over PerlSignal when coercing.

WWW: https://metacpan.org/release/MooseX-Types-Signal