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Function: map()

Call Signature​

map<T, U>(option, fn): Option<U>

Defined in: option/map/index.ts:35

Maps over the Some value of an Option.

If the Option is Some, applies the function to its value and returns a new Some. If the Option is None, returns None unchanged.

This is the functor map operation for Option.

Type Parameters​

T​

T

U​

U

Parameters​

option​

Option<T>

The Option to map over

fn​

(value) => U

Function to transform the Some value

Returns​

Option<U>

A new Option with the transformed value

Example​

// Data-first
map(some(5), x => x * 2) // => Some(10)
map(none(), x => x * 2) // => None

// Data-last (in pipe)
pipe(
  some(5),
  map(x => x * 2),
  map(x => x + 1)
) // => Some(11)

See​

  • flatMap - for chaining Option-returning functions
  • filter - for conditionally keeping values

Call Signature​

map<T, U>(fn): (option) => Option<U>

Defined in: option/map/index.ts:36

Maps over the Some value of an Option.

If the Option is Some, applies the function to its value and returns a new Some. If the Option is None, returns None unchanged.

This is the functor map operation for Option.

Type Parameters​

T​

T

U​

U

Parameters​

fn​

(value) => U

Function to transform the Some value

Returns​

A new Option with the transformed value

(option): Option<U>

Parameters​

option​

Option<T>

Returns​

Option<U>

Example​

// Data-first
map(some(5), x => x * 2) // => Some(10)
map(none(), x => x * 2) // => None

// Data-last (in pipe)
pipe(
  some(5),
  map(x => x * 2),
  map(x => x + 1)
) // => Some(11)

See​

  • flatMap - for chaining Option-returning functions
  • filter - for conditionally keeping values