Perl is joy to write (especially with Modern::Perl qw(2016) and feature qw(signatures)) but is hard to read. I can write lot of code in single line with map/reduce/split/join/regexps, but without chaining of operators it is mess, because order of operators is opposite to order of execution. It because of traditional function or operator invocation syntax: "x(a1, y(a2, z(a3, a4), a5), a6)", instead of modern chain of calls: "z(a3,a4).y(a2, a5).x(a1, a6)" . The more operators I pack into single line of code with traditional syntax, the harder it to read.

Perl6 has "feed operator", but it is not ported to perl5 to date. Perl6 syntax is clean:

    my @array = <7 8 9 0 1 2 4 3 5 6 7 8 9>;
    @array ==> unique()
           ==> sort()
           ==> reverse()
           ==> my @final-array;
    say @final-array;

but perl6 is slow, so it is not gaining any popularity.