use strict;

my $str = sub { "params.$_[0].arg" };

sub do_something { print +shift, "\n" }

for my $idx (0..10) {
    do_something( $str->($idx) );
}
[download]

output:

params.0.arg
params.1.arg
params.2.arg
params.3.arg
params.4.arg
params.5.arg
params.6.arg
params.7.arg
params.8.arg
params.9.arg
params.10.arg
[download]