Can I split an IEnumerable into two by a boolean criteria without two queries?

Question

Can I split an IEnumerable into two IEnumerable using LINQ and only a single query/LINQ statement?

I want to avoid iter

Answer 1

You can use this:

var groups = allValues.GroupBy(val => val.SomeProp);

To force immediate evaluation like in your example:

var groups = allValues.GroupBy(val => val.SomeProp)
                      .ToDictionary(g => g.Key, g => g.ToList());
List trues = groups[true];
List falses = groups[false];