{
        my &cmp := &by.arity == 2 ?? &by !! { $^a cmp $^b };
        my Bool $is-initialized = False;
        for @values {
            if $is-initialized {
                $min = $_ if cmp($_, $min) < 0;
            } else {
                if .defined {
                    $min = $_;
                    $is-initialized = True;
                }
            }
        }