swap

Exchange two values.

Alternatives: swap, swap$.
Similar: get, set, swap, remove.

function swap(x, k, l)
// x: a map
// k: a key
// l: another key

const map = require('extra-map');

var x = new Map([['a', 1], ['b', 2], ['c', 3], ['d', 4]]);
map.swap(x, 'a', 'b');
// → Map(4) { 'a' => 2, 'b' => 1, 'c' => 3, 'd' => 4 }

map.swap(x, 'a', 'd');
// → Map(4) { 'a' => 4, 'b' => 2, 'c' => 3, 'd' => 1 }

References

• List-Extra.swapAt: elm
• Collections.swap: Java
• pure-swap: @alferov