size_t len(T)(T[] arr) {

    return arr.length;

}

​

int[] arr0 = [1, 1, 2, 3, 5, 8];

char[] arr1 = ['a', 'b', 'c', 'd', 'e'];

​

void writeResult(T)(T[] param, size_t result) {

    import std.stdio;

    import std.format;

    writeln(format("%s --> %s", param, result));

}

​

void main()

{

    writeResult(arr0, len(arr0));

    writeResult(arr1, len(arr1));

}