c# combine yield return of multiple functions

Question

c# yield compute will delay execution of each iteration of a loop only when that particular enumerated element is actually needed by the caller. Is it possible to combine multiple such yield return functions and still expose a dynamically enumerated set to the ultimate caller ?

public IEnumerable<string> GetDelayedCompute1()
{
    // compute ...
    foreach(var s in results)
    {
        yield return s;
    }
}

public IEnumerable<string> GetDelayedCompute2()
{
    // compute ... 
    foreach(var s in results)
    {
        yield return s;
    }
}

public IEnumerable<string> GetResults()
{
    // how to combine results of GetDelayedCompute1 and GetDelayedCompute2
    // and yield return without forcing enumeration
}

Answer 1

The results of a LINQ operation are lazy-evaluated, so you can just:

public IEnumerable<string> GetResults()
{
    return GetDelayedCompute1().Concat(GetDelayedCompute2());
}

The results are not actually materialized until you enumerate the result of GetResults().

Answer 2

Is it possible to combine multiple such yield return functions

Yes, just continue the mechanism of yield returns by foreaching over each of the methods.

foreach (var str in GetDelayedCompute1())
    yield return str;

foreach (var str in GetDelayedCompute2())
    yield return str;

---

Otherwise Union the result and return

 return GetDelayedCompute1().Union(GetDelayedCompute2());