// Replaces value at $index from $list by $value
// -------------------------------------------------------------------------------
// @documentation http://sassylists.com/documentation/#replace-nth
// -------------------------------------------------------------------------------
// @example replace-nth(a b c,   2, z) => a, z, c
// @example replace-nth(a b c,   0, z) => error
// @example replace-nth(a b c,  10, z) => error
// @example replace-nth(a b c,  -1, z) => a, b, z
// @example replace-nth(a b c, -10, z) => error
// -------------------------------------------------------------------------------
// @param $list [List] : list
// @param $index [Number] : index to update
// @param $value [Literal] : new value for index $index
// -------------------------------------------------------------------------------
// @raise [Error] if $index isn't an integer
// @raise [Error] if $index is 0
// @raise [Error] if abs value of $index is strictly greater than length of $list
// -------------------------------------------------------------------------------
// @return [List] | false

@function replace-nth($list, $index, $value) {
    $result: false;

    @if type-of($index) != number {
        @warn "List index #{$index} is not a number for `replace-nth`/`remove-nth`.";
        @return $result;
    }

    @else if $index == 0 {
        @warn "List index 0 must be a non-zero integer for `replace-nth`/`remove-nth`.";
        @return $result;
    }

    @else if abs($index) > length($list) {
        @warn "List index is #{$index} but list is only #{length($list)} item long for `replace-nth`/`remove-nth`.";
        @return $result;
    }

    @else {
        $result: ();
        $index: if($index < 0, length($list) + $index + 1, $index);  

        @for $i from 1 through length($list) {
            @if $value and $value != "" and $value != () {
                $result: append($result, if($i == $index, $value, nth($list, $i)));
            }
        }
    }

    @return $result;
}