purely functional table

table.js

// found this perl in "The Seasoned Schemer".
// just love how simple this implementation while coming
// with really great features.

function empty_table() {}

function extend(table, key, value) {
    return function(k) {
        if(k === key) {
            return value;
        }
        else {
            return table(k);
        }
    }
}

var x = empty_table;
var y;

x = extend(x, '1', 'one');
x = extend(x, '2', 'two');

y = extend(x, '3', 'trois');
x = extend(x, '3', 'three');

console.log(x('1')); // one
console.log(x('2')); // two

console.log(y('1')); // one
console.log(y('2')); // two

console.log(x('3')); // three
console.log(y('3')); // trois