Question

Is it possible to rewrite this function without foreach(), using LINQ-only?

    IEnumerable<string> Unwrap(IEnumerable<IEnumerable<string>> data)
    {
        var result = new List<string>();
        foreach (var d in data)
        {
            result.AddRange(d);
        }
        return result;
    }

Answer 1

Just use Enumerable.SelectMany:

IEnumerable<string> Unwrap(IEnumerable<IEnumerable<string>> data)
{
    return data.SelectMany(d => d);
}