Problem Statement

Create a function, compose,   whose two arguments   f   and   g,   are both functions with one argument.

The result of compose is to be a function of one argument, (lets call the argument   x),   which works like applying function   f   to the result of applying function   g   to   x.

Reference: Function composition Hint: In some languages, implementing compose correctly requires creating a closure.

Let's start with the solution:

sub compose {
    my ($f, $g) = @_;

    sub {
        $f -> ($g -> (@_))
    };
}

use Math::Trig;
print compose(sub {sin $_[0]}, \&asin)->(0.5), "\n";