pairmutator.js

/**
 * changes the pair <CODE>p</CODE> such that its head is <CODE>x</CODE>.
 * @param {pair} p - given pair
 * @param {value} x - given value
 * @returns {undefined} undefined
 */
function set_head(p, x) {}

/**
 * changes the pair <CODE>p</CODE> such that its tail is <CODE>x</CODE>.
 * @param {pair} p - given pair
 * @param {value} x - given value
 * @returns {undefined} undefined
 */
function set_tail(p, x) {}