Using Pattern Matching

Pattern Matching is one of the fundamental concepts of functional programming.

This concept can be used to replace a lot of code flow structures, such as:

• If-else statements

• Switch-cases

• Loops (for, foreach, while e do)

• Types comparison

A pattern matching in the F# language to replace an if statement has a syntax similar to:

match boolExpression with
| true  -> //pattern when true 
| false -> //pattern when false

You can also using patterns to compare an int value:

let value = 10
match value with
| 1 | 2 | 3         -> //When the value is 1, 2 or 3
| n when n % 2 = 0  -> //When the value is an even number
| 5                 -> //When the value is equals to 5
| _                 -> //Other cases

There are a lot of benefits to using pattern matching, so, from C# 7.0 version it is possible to use this feature natively in the language, according to the documentation of the Microsoft.

As an implementation in Tango library, some types have a method called Match.

These methods receive lambda expressions for each pattern as a parameter, according to each type.

Besides that, there are also an implementation of a method called Match2, similar to the previous one, but in this case, the patterns are applied to two different values simultaneously.