use strict;   # DO NOT OMIT.
use warnings; # DITTO.

my $dir = shift || die "Gimme a dir full of text files!\n";
my $random_texter = build_texter(dir => $dir);

print $random_texter->();

exit;

sub build_texter {
    require List::Util;
    require Path::Tiny;
    require Carp;
    my %arg = ( dir => "YOU FORGOT TO SET THE DIR!",
                suffix => "", # e.g., .txt
                @_ );
    my $dir = Path::Tiny::path($arg{dir});
    -d $dir && -r _ || Carp::croak("$dir is not a readable directory");
    my @files = grep /\Q$arg{suffix}\E\z/, grep -f, $dir->children;
    Carp::croak("There are no matching files in $dir") unless @files;
    sub { [ List::Util::shuffle( @files ) ]->[0]->slurp };
}