does kotlin provide any list implementation that can do efficient (constant-time) cons/cdr, for use ...

# announcements

[myaa]

does kotlin provide any list implementation that can do efficient (constant-time) cons/cdr, for use when designing tail recursive functions that operate on lists?

[Ryan]

you can write an extension for linkedlist.

[myaa]

if you mean java's LinkedList i believe that's doubly linked, so efficient (immutable) cons/cdr isn't possible

[Jakub Gwóźdź]

there is kotlinx.collections.immutable project that may be of help to you, but I'm not sure if that's exactly what you're looking for.

[Kroppeb]

Do you mean a stack?
You want to push and pop data no?
Technically you can just use a list and add an element or remove one at the end, or use deque if you want a nicer interface and want to push and pop on both sides

[myaa]

in the end i just went with a simple custom definition of a linked list: class Node<T>(val head: T, val tail: Node<T>?) . i guess i was just a bit too used to languages like scala/haskell where this is the default list type and constant-time cons is a very fundamental operator

it also looks like the Sequence type (immutable, stateless) might be relevant for functional idioms