As fore mentioned, when LINQ to Objects’ collection queries and value queries are called, they start to evaluate query result. When sequence queries are called, they do not evaluate any query result,

After understanding how to use LINQ to Objects queries, this chapter starts to discuss how these queries work internally, including how they execute and how they are implemented. These insights help d

As fore mentioned, LINQ to Objects standard query methods (also called standard query operators) are provided as static methods of System.Linq.Enumerable type, most of which are IEnumerable<T> extensi

LINQ to Objects queries .NET objects in local memory of current application or service. Its data source and the queries are represented by IEnumerable<T> interface, and it is executed sequentially. Th

Pattern matching is a common feature in functional languages. C# 7.0 introduces basic pattern matching in is expression and switch statement, including constant value as pattern and type as pattern, a

Immutability is an important aspect of functional programming. As discussed in the introduction chapter, imperative/object-oriented programming is usually mutable and stateful, and functional programm

The previous chapter discusses that functional programming encourages modelling data as immutable. Functional programming also encourages modelling operations as pure functions. The encouraged purity

In programming languages with subtyping support, variance is the ability to substitute a type with a different subtype or supertype in a context. For example, having a subtype and a supertype, can a f