ysth@raven:~$ perl -wle'sub i { print "installing: $_[0]" } i(Compress::Zlib)'
installing: Compress::Zlib

ysth@raven:~$ perl -wle'sub i { print "installing: $_[0]" } i(Compress-Zlib-1.42)'
Argument "Zlib" isn't numeric in subtraction (-) at -e line 1.
Argument "Compress" isn't numeric in subtraction (-) at -e line 1.
installing: -1.42

ysth@raven:~$ perl -wle'sub i { print "installing: $_[0]" } i(Compress-Zlib)'
Argument "Zlib" isn't numeric in subtraction (-) at -e line 1.
Argument "Compress" isn't numeric in subtraction (-) at -e line 1.
installing: 0