How to implement lazy sequence (iterable) in scala?

Question

I want to implement a lazy iterator that yields the next element in each call, in a 3-level nested loop.

Is there something similar in scala to this snippet of c#:

foreach (int i in ...)
    {
        foreach (int j in ...)
        {
            foreach (int k in ...)
            {
                 yield return do(i,j,k);
            }
        }
    }

Thanks, Dudu

Answer 1

You can use a Sequence Comprehension over Iterators to get what you want:

for {
    i <- (1 to 10).iterator
    j <- (1 to 10).iterator
    k <- (1 to 10).iterator
} yield doFunc(i, j, k)

If you want to create a lazy Iterable (instead of a lazy Iterator) use Views instead:

for {
    i <- (1 to 10).view
    j <- (1 to 10).view
    k <- (1 to 10).view
} yield doFunc(i, j, k)

Depending on how lazy you want to be, you may not need all of the calls to iterator / view.