In D language we can tie function to a template by alias:
struct BinaryTree(T, alias cmp_fun) {
alias V = T
alias compare = com_fun;
}
void main() {
alias Tree = BinaryTree!(int, (a, b) => a < b);
}
Run
It is no need to store the comparator in the tree object, also it is no need to
pass the comparison function to other functions. Since it is possible to
extract the comparison function from the type:
void insert(T)(T tree, T.V value) {
...
if(T.compare(value, node.value)) {...}
}
Run
The same nim code failed to compile:
type
BinaryTree[V, compare] = object
value: V
proc insert(tree: BinaryTree, value: BinaryTree.V): bool =
BinaryTree.compare(value, tree.value) # Error: a type conversion takes
exactly one argument
var a = BinaryTree[int, proc(a, b: int): bool = a < b](value: 10)
echo insert(a, 20)
Run
