original.name="RecursiveType_Valid_21"
======
>>> main.whiley


type Link is {LinkedList next, int data}

type LinkedList is null | Link

function sum(LinkedList l) -> int:
    if l is null:
        return 0
    else:
        return l.data + sum(l.next)

public export method test() :
    LinkedList l1 = {next: null, data: 1}
    LinkedList l2 = {next: l1, data: 2}
    LinkedList l3 = {next: l2, data: 3}
    assume sum(l1) == 1
    assume sum(l2) == 3
    assume sum(l3) == 6

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