whenHasInformation

Functional pattern matching based on the literal information of an Either. The function is executed only when the information (or one of the informations) matches.

Interactive example

Syntax

Classic signature

function whenHasInformation<
  const GenericInput extends unknown,
  GenericInformation extends ReturnType<typeof eitherInformationKind.getValue<GenericInput>>,
  const GenericOutput extends AnyValue
>(
  input: GenericInput,
  information: GenericInformation | GenericInformation[],
  theFunction: (value: Unwrap<Extract<GenericInput, Kind<typeof eitherInformationKind.definition, GenericInformation> & WrappedValue>>) => GenericOutput
): GenericOutput | Exclude<GenericInput, Kind<typeof eitherInformationKind.definition, GenericInformation>>;

Curried signature

function whenHasInformation<
  const GenericInput extends unknown,
  GenericInformation extends ReturnType<typeof eitherInformationKind.getValue<GenericInput>>,
  const GenericOutput extends AnyValue
>(
  information: GenericInformation | GenericInformation[],
  theFunction: (value: Unwrap<Extract<GenericInput, Kind<typeof eitherInformationKind.definition, GenericInformation> & WrappedValue>>) => GenericOutput
): (input: GenericInput) => GenericOutput | Exclude<GenericInput, Kind<typeof eitherInformationKind.definition, GenericInformation>>;

Parameters

• information: Literal or array of accepted literals.
• theFunction: Callback invoked only when the information matches.
• input: Value to process immediately (otherwise use the curried version in your pipes).

Return value

• Classic signature: returns either the callback result or the initial value (if no info matches).
• Curried signature: returns a function ready to compose.

Use cases

• Write exhaustive pattern matching without switch or nested if.
• Factor shared processing for several successes/errors (information accepts an array).
• React precisely to business states described via E.right/E.left.

See also

• hasInformation – Low-level type guard.
• whenIsRight / whenIsLeft – To operate only by side.