Didn't mean to obfuscate that, it's just a one-liner. Here's how it works. Perl setup:

perl -Mautodie -we '
die "not apple mac" unless ${^O} eq "darwin";

Open a pipe to the applescript compiler and print:

open $f, "|-", "osacompile -o CPAN.app"; print $f qq~

Display applescript dialog to get user input:

set CPAN to text returned of (display dialog "Search CPAN for" with title "Perl CPAN Search" default answer "")\n

Exit on empty form:

if CPAN is equal to "" then return\n

Open website with user input:

do shell script("open \\"https://metacpan.org/search?q=" & CPAN & "\\"")

Back to perl, close the print and pipe, open the app:

~;
close $f;
system("open CPAN.app")'

Flowchart:

perl -> applescript -> perl -> app -> CPAN!