C# functional quicksort is failing
- by Rubys
I'm trying to implement quicksort in a functional style using C# using linq, and this code randomly works/doesn't work, and I can't figure out why.
Important to mention: When I call this on an array or list, it works fine. But on an unknown-what-it-really-is IEnumerable, it goes insane (loses values or crashes, usually. sometimes works.)
The code:
public static IEnumerable<T> Quicksort<T>(this IEnumerable<T> source)
where T : IComparable<T>
{
if (!source.Any())
yield break;
var pivot = source.First();
var sortedQuery = source.Skip(1).Where(a => a.CompareTo(source.First()) <= 0).Quicksort()
.Concat(new[] { pivot })
.Concat(source.Skip(1).Where(a => a.CompareTo(source.First()) > 0).Quicksort());
foreach (T key in sortedQuery)
yield return key;
}
Can you find any faults here that would cause this to fail?
