Function head

head<T>(list: List.List<T>): Option.Option<T>

Gets the first element of the list.

Type Parameters

T

Parameters

list: List.List<T>
The source list.

Returns Option.Option<T>

The first element of list if exists.

Examples

Example

expect(head(empty())).toStrictEqual(Option.none());
expect(head(fromString("hoge"))).toStrictEqual(Option.some("h"));

const list = singleton(42);
expect(head(list)).toStrictEqual(Option.some(42));
expect(head(list.rest())).toStrictEqual(Option.none());