JavaScript currying 2 - Tacit programming (Point-free style)

Tacid programming (i.e., Point-free style) is a programming paradigm, where function definition does not refer to the function arguments. Function declaration, on the other hand, requires any formal parameters to be declared. Every point-free function has its closure scope. The closure is created at the function creation time - when the function is invoked. Every form of the curried function is a form fo higher-order-function

const add = (a) => (b) => a + b;
const incrementByOne = add(1); // partially applied function
incrementByOne(9); // => 10

When we create incrementByOne with function call add(1), the a parameter from add function get fixed to 1 inside the returned function that gets assigned to incrementByOne function. When we call incrementByOne function with b parameter fixed to 9 function application completes, and returns the sum of 1 and 9.

// Another example of point-free style function
const g = (n) => n + 1;
const f = (n) => n * 2;
const h = (x) => f(g(x));
h(20); // => 42

Comments

[HuzaifaMS]

I tried this code piece and I found that a and b are of type any in typescript. Is there anyway to get the code to work with type annotations.

[Lukas Polak]

Yes Muhammad, you can use this

const add = (a: number) => {
  return (b: number): number => {
    return a + b;
  };
};

[HuzaifaMS]

Thank you. I appreciate you taking the time to reply.

May Peace and Blessings be upon you and your family.