orElse

Allows recovering from Error values with a handler function.

This feature is experimental!

This API is still experimental, so it may change or be removed in future versions. You should not rely on it for production applications.

Signature

Type(what is this?)

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

Documentation

Allows recovering from Error values with a handler function.

While .chain() allows one to sequence operations, such that the second operation is ran only if the first one succeeds, the .orElse() method allows one to recover from an Error by running a function that provides a new Result value.

Example:

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

Result.Ok(4).orElse(error => Result.Ok(error + 1));
// ==> Result.Ok(4)

Result.Error(4).orElse(error => Result.Ok(error + 1));
// ==> Result.Ok(5)

Result.Error(4).orElse(error => Result.Error(error - 1));
// ==> Result.Error(3)

Properties

Source Code

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

{
    /*~*/
    Error: function orElse(handler) {
      assertFunction('Result.Error#orElse', handler);
      return handler(this.value);
    },

    /*~*/
    Ok: function orElse(handler) {
      assertFunction('Result.Ok#orElse', handler);
      return this;
    }
  }