Functions

Use functions to modularize shared logic such as data extraction and generation.

Definition

Use the func keyword to define either single or multi-line functions. Any valid expression can be used on the right-hand side of the -> symbol.

Knot

knot
func increment(value: integer) -> value + 1;
func addAndDouble(lhs: integer, rhs: integer) -> {
  let total = lhs + rhs;
  total * 2;
};

knot
func increment(value: integer) -> value + 1;
func addAndDouble(lhs: integer, rhs: integer) -> {
  let total = lhs + rhs;
  total * 2;
};

TypeScript

tsx
function increment(value: number) {
  return value + 1;
}
function addAndDouble(lhs: number, rhs: number) {
  let total = lhs + rhs;
  return total * 2;
}

tsx
function increment(value: number) {
  return value + 1;
}
function addAndDouble(lhs: number, rhs: number) {
  let total = lhs + rhs;
  return total * 2;
}

Empty Arguments

If your function does not take any arguments you can drop the parentheses as well.

Knot

knot
func stringFactory -> "string";
const result = stringFactory();

knot
func stringFactory -> "string";
const result = stringFactory();

TypeScript

tsx
function stringFactory() {
  return "string";
}
const result = stringFactory();

tsx
function stringFactory() {
  return "string";
}
const result = stringFactory();

Default Arguments

You can make your arguments optional by passing default values. However, if you add a default value you must also add default values for all subsequent arguments.

Knot

knot
func add(lhs: integer, rhs = 10) -> lhs + rhs;
const result = add(5, 2);

knot
func add(lhs: integer, rhs = 10) -> lhs + rhs;
const result = add(5, 2);

TypeScript

tsx
function add(lhs: number, rhs = 10) {
  return lhs + rhs;
}
const result = add(5, 2);

tsx
function add(lhs: number, rhs = 10) {
  return lhs + rhs;
}
const result = add(5, 2);