whenIsSelected

Runs a callback on the unwrapped Either payloads selected by an exhaustive information selector and forwards all other inputs unchanged.

The selector maps every possible information of the input union to true or false. A true entry executes the callback with the unwrapped payload; a false entry preserves the original Either.

Interactive example

Syntax

Classic signature

function whenIsSelected<
  GenericInput extends unknown,
  GenericSelector extends Record<Information, boolean>,
  GenericOutput,
>(
  input: GenericInput,
  selector: GenericSelector,
  theFunction: (value: UnwrappedSelectedInputs) => GenericOutput,
): GenericOutput | UnselectedInputs

Curried signature

function whenIsSelected<
  GenericInput extends unknown,
  GenericSelector extends Record<Information, boolean>,
  GenericOutput,
>(
  selector: GenericSelector,
  theFunction: (value: UnwrappedSelectedInputs) => GenericOutput,
): (input: GenericInput) => GenericOutput | UnselectedInputs

Parameters

• selector: Exhaustive object mapping every possible input information to true or false.
• theFunction: Callback receiving the unwrapped payload of the selected informations.
• input: Value to process immediately, or later through the curried form.

Return value

Returns the callback result when the current information is selected with true. Otherwise, it returns the original input unchanged.

When a selector entry is typed as boolean, the return type includes both the callback result and the original Either for that information.

See also

• whenHasInformation - Selects one or several informations without an exhaustive selector.
• unwrapSelection - Unwraps selected payloads without applying a callback.
• matchInformation - Exhaustive callback-based matching by information.