Under development.
The PERL fingerprint is designed to provide a basic, no-frills interface to the Perl language.
After successfully loading PERL, the instructions E, I, and S take on new semantics.
S ('Shelled') pushes a 0 on the stack if the Perl language is already loaded (e.g. the interpreter is written in Perl). It pushes a 1 on the stack otherwise, indicating that the Perl language will be shelled when needed.
E ('Eval') pops a 0gnirts string and
performs a Perl eval()
on it, possibly (or
not) shelling Perl as indicated by S above.
The result of the call is pushed as a 0gnirts string
back onto the stack.
I ('Int Eval') acts the same as E, except that the result of the call is converted to an integer and pushed as a single cell onto the stack.