Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.1)
// Compass (v0.13.alpha.10)
// ----

@function f-fold($func, $list, $initial, $args...) {
    $start: 1;
    @if $initial == null {
        // If there's no initial value, use the first in the list.
        $start: 2;
        $initial: nth($list, 1);
    }
    $prev: $initial;
    @for $i from $start through length($list) {
        $next: nth($list, $i);
        $prev: call($func, $prev, $next, $args...);
    }
    @return $prev;
}

@function join-with-separator($val1, $val2, $separator) {
    @return "#{$val1}#{$separator}#{$val2}";
}

p {
    joined: join-with-separator("About", "Links", " | ");
    many-joined: f-fold(join-with-separator, ("Home" "About" "Links" "Contact"), null, " | ");
}

SassMeister-output.css

p {
  joined: "About | Links";
  many-joined: "Home | About | Links | Contact";
}