I see two problems:

1. The mixing of ' and ". Your single quotes around the '42' are the first thing breaking you
2. The semicolon afte the if { } and before the else

fappy@flux[62] tmp > perl -e 'if( q{42} =~ /[:^digit:]/) {print "42 is
+ a digit\n"} else {print "42 is not a digit\n"}';
42 is not a digit
[download]

Now the questions remainns, what did you really want to test?