Revisiting Maybe monad using C# 8.0 Pattern Matching

Source Code .NET Fiddle : Maybe Monad Example C# 8.0 Pattern Matching

To be honest i didn't like the pattern matching feature the first time i show it. But i rewrote some sample functional code and i can say i might be a fan.

if you are not familiar with pattern matching read the previous article :

Evolution of Pattern Matching up until C# 8.0

this article revises the Maybe monad seen previously

Null Object design pattern and Maybe Monad in C#

We will rewrite Maybe using C# 8.0 pattern matching

this is the initial

and now we can just simply replace it with

placing the map definition in the base class

public abstract class Maybe<T>
    {
        public Maybe<T1> Map<T1>(Func<T, T1> f) =>
         this switch
         {
             None<T> { } => new None<T1>(),
             Some<T> { Value: var v } => new Some<T1>(f(v)), 
         };
    }

and we can use it like this :

var result = new Some<int>(4)
                .Map(v => $"number is  : {v}")
                switch         //another switch to extract the value
            {
                None<string> { } => "Not found",
                Some<string> { Value: var v } => "some" + 5,
                _ => throw new NotImplementedException(),
            };

we can similarly define the Bind :

here i used extension methods but we can put that also in the base class Maybe<T>.

Practical functional C#