44. Curry Function

Implement curry - convert a function into a curried version based on fn.length (its declared arity).

1) Input

• Accept a function fn.

2) Curried behavior

• Return a function that can collect arguments across multiple calls.
• Each call may provide one or more arguments.
• Once collected argument count is at least fn.length, invoke fn and return its result.

3) Invocation policy

• Use fn.length as the required argument count.
• If extra arguments are provided on the final call, still invoke normally.
• Preserve dynamic this from the call that finally triggers execution.

4) Arity-0 edge case

• For fn.length === 0, the curried function should execute on the first invocation.

Examples

const add3 = (a, b, c) => a + b + c
const cAdd3 = curry(add3)

cAdd3(1)(2)(3)     // 6
cAdd3(1, 2)(3)     // 6
cAdd3(1)(2, 3)     // 6
cAdd3(1, 2, 3, 4)  // 6 (extra args allowed)