Titleeither

Titleeither is a conceptual programming construct used in functional programming to pair a descriptive title with an Either value. The idea is to attach contextual metadata to a value that may represent a success or an error, so that downstream processing and error reporting carry both the result and a human-friendly label.

Definition and structure In its simplest form, a titleeither wraps a title string alongside an Either value. In a Haskell-inspired representation, this can be described as a data wrapper such as TitleEither e a = TitleEither { title :: String, value :: Either e a }. The title is immutable once created, and the value field holds either an error (Left e) or a success (Right a). The main purpose is to preserve the title as the value flows through a series of transformations or validations.

Usage and behavior When transformations are applied to the inner Either, care is taken to preserve the associated title. This allows functions that map or chain results to keep the same label, or to propagate a modified title if appropriate. Typical usage scenarios include validation pipelines, error reporting, and localization where the same contextual heading should accompany related values or error messages.

Advantages and considerations Using a titlewith pattern can improve debuggability and user-facing error messages by providing contextual labels without requiring separate error-handling structures. However, it adds a layer of indirection and may incur minor performance overhead. It is not a standard library construct in mainstream languages, but can be implemented as a lightweight wrapper in languages that support algebraic data types or wrappers.

See also Neither the exact term nor its canonical implementation is universally standardized. See also Either, Validation, Contextual errors, and error labeling patterns.