Close but no cigar

• First let's see some wrong answers.

• What's wrong with this?

        sub halts {
          my ($source_code, $input) = @_;

          my $function = eval $source_code;
          $function->($input);
          # I guess it halted!
          return 1;
        }

• It doesn't always produce an answer

• If that were allowed, this would be a simpler solution:

        sub halts {
          my ($source_code, $input) = @_;
          1 while 1;          # Har har har
        }

Next

Copyright © 2005 M. J. Dominus