In the interests of readability, code that can be simplified should be simplified. To that end, there are several ways IEnumerable language integrated queries (LINQ) can be simplified

• Use OfType instead of using Select with as to type cast elements and then null-checking in a query expression to choose elements based on type.
• Use OfType instead of using Where and the is operator, followed by a cast in a Select
• Use an expression in Any instead of Where(element => [expression]).Any().
• Use Count instead of Count() when it’s available.
• Don’t call ToArray() or ToList() in the middle of a query chain.

Using EntityFramework may require enforcing client evaluations. Such queries should use AsEnumerable() instead of ToArray() or ToList() in the middle of a query chain.

Noncompliant Code Example

seq1.Select(element => element as T).Any(element => element != null);  // Noncompliant; use OfType
seq2.Select(element => element as T).Any(element => element != null && CheckCondition(element));  // Noncompliant; use OfType
seq3.Where(element => element is T).Select(element => element as T); // Noncompliant; use OfType
seq4.Where(element => element is T).Select(element => (T)element); // Noncompliant; use OfType
seq5.Where(element => [expression]).Any();  // Noncompliant; use Any([expression])

var num = seq6.Count(); // Noncompliant
var arr = seq.ToList().ToArray(); //Noncompliant
var count = seq.ToList().Count(x=>[condition]); //Noncompliant

Compliant Solution

seq1.OfType<T>().Any();
seq2.OfType<T>().Any(element => CheckCondition(element));
seq3.OfType<T>();
seq4.OfType<T>();
seq5.Any(element => [expression])

var num = seq6.Count;
var arr = seq.ToArray();
var count = seq.Count(x=>[condition]);