OutputEither

OutputEither is a concept often encountered in functional programming, particularly in languages that embrace algebraic data types. It represents a value that can be one of two distinct types, conventionally named 'Left' and 'Right'. This structure is frequently used for error handling or to distinguish between a successful result and an error condition.

The 'Left' side is typically used to hold an error value, such as a string describing the problem or a more complex error object. The 'Right' side, conversely, holds the successful result of an operation. This pattern provides a clear and explicit way to manage outcomes without resorting to exceptions or nullable types.

Functions that might fail or return a specific type of result can be designed to return an OutputEither. This forces the caller to consider both possible outcomes, either by pattern matching on the returned value or by using combinator functions provided by libraries that support this construct. Common operations on OutputEither include mapping over the 'Right' value, folding to extract a value by providing a function for both 'Left' and 'Right', and sequencing operations where a chain of 'Right' values can be processed while short-circuiting on the first 'Left'.

The OutputEither type promotes more robust and predictable code by making the potential for failure an explicit part of the function's signature. This contrasts with traditional imperative error handling mechanisms that can be more implicit and harder to track.