JavaScript version
unary.js
const unary = (fn) => (arg) => fn(arg);
Examples
examples.js
['1', '2', '3', '4', '5'].map(unary(parseInt)); // [1, 2, 3, 4, 5]
const unary = (fn) => (arg) => fn(arg);
['1', '2', '3', '4', '5'].map(unary(parseInt)); // [1, 2, 3, 4, 5]