What is the easiest way to add an element to the end of the list?

Question

As:: : 'a -> 'a list -> 'a list is used to add an element to the begin of a list, Could anyone tell me if there is a function to add an element to the end of a list? If not, I guess List.rev (element::(List.rev list)) is the most straightforward way to do it?

Thank you!

Answer 1

The reason there's not a standard function to do this is that appending at the end of a list is an anti-pattern (aka a "snoc list" or a Schlemiel the Painter algorithm). Adding an element at the end of a list requires a full copy of the list. Adding an element at the front of the list requires allocating a single cell—the tail of the new list can just point to the old list.

That said, the most straightforward way to do it is

let append_item lst a = lst @ [a]

Answer 2

list@[element] should work. @ joins lists.