#!/usr/local/bin/perl

use strict; use warnings;

#  Working versions.
warn $_ for qw/ p / ;

for my $var qw/ p / { warn $var }

for ( qw/ p / ) { warn $_ }

#  Fails at compile time.
#  This is commented just to have the program be compiled and get error via
#  eval.
#for qw/ p / { warn $_ };

my $code = eval "for qw/ p / { warn $_ } " ;
warn "code: $code  error: $@";

__END__

Error message produced ...

   Missing $ on loop variable at -e line 1 (#1)

... diagnostics module adds ...

    (F) Apparently you've been programming in csh too much.  Variables are
        always mentioned with the $ in Perl, unlike in the shells, where it can
        vary from one line to the next.