Question

Why this code doesn’t work?

public static IList<float> CreateModifiedList(IList<float> list)
{
    IList<float> modifiedList= list.Aggregate(new List<float> (), (l, item) =>l.Add(++item));

    return modifiedList;
}

When I try to compile it using Mono I get the following error:

error CS0029: Cannot implicitly convert type void' to
System.Collections.Generic.List’

Answer 1

It does not work, because l.Add(++item) is not returning your aggregate (list of float) – it returns void. Second argument should be of type Func<List<float>, float, List<float>>. Change your code to return aggregation variable:

(l, item) => { l.Add(++item); return l; }

BTW What you are doing could be achieved this way:

IList<float> modifiedList = list.Select(item => ++item).ToList();