Type Alias Head<T, Options>

Head: IsNever<T, $Selection.Branch> extends infer R
    ? R extends $Then
        ? Options["$never"]
        : R extends $Else
            ? T["length"] extends 0 ? Options["caseEmptyTuple"] : T[0]
            : never
    : never

🦴 utilities 🔢 customizable

Gets the first entry in the tuple or the type of array T.

Type Parameters

T extends readonly unknown[]
Options extends Head.Options = Head.DefaultOptions

Example

type R = Head<[1, 2, 3]> // 1
type R = Head<string[]> // string

type R = Head<[]> // never

Type Param: Options['$never']

Return type when T is never. Default to never.

Type Param: Options['caseEmptyTuple']

Return type when T is []. Default to never.