map

Transforms the value inside of a Result structure with an unary function without changing the context of the computation. That is, Error values continue to be Error values, and Ok values continue to be Ok values.

Signature

Type(what is this?)

forall a, b, c:
  (Result a b).((b) => c) => Result a c

Documentation

Example:

const Result = require('folktale/result');

function increment(value) {
  return value + 1;
}

Result.Ok(1).map(increment);
// ==> Result.Ok(2)

Result.Error(1).map(increment);
// ==> Result.Error(1)

Properties

Source Code

Defined in source/result/result.js at line 75, column 19

{
    /*~*/
    Error: function map(f) {
      assertFunction('Result.Error#map', f);
      return this;
    },

    /*~*/
    Ok: function map(f) {
      assertFunction('Result.Ok#map', f);
      return Ok(f(this.value));
    }
  }