Just finishing up Functional Javascript by Michael Fogus. Great read. Finally feeling like I understand functional programming, and has changed the way I write clean, functional code. Here’s an brief example, using curry and partial.
//Currying vs. Partial
const add = (x, y) => x + y;
const addAny = (...args) => {
return args.reduce((prev, next) => prev + next, 0);
}
// curry to specific depth
function curry(fun, x) {
return function(y) {
return fun(x, y);
}
}
// partial to any number of arguments
function partial(/* pargs */) {
const pargs = [...arguments];
const fun = pargs.shift();
return function(/* bargs */) {
const bargs = [...pargs, ...arguments];
return fun.apply(fun, bargs);
}
}
const add10 = curry(add, 10);
console.log('curry', add10(10)); // 20
const partial10 = partial(add, 10);
console.log('partial', partial10(12)); // 22
const partialAny = partial(addAny);
console.log('partialAny', partialAny(1, 2, 3, 1)); // 7