Swift Functional Programming - Second Edition

Custom operator definition

We can define custom operators using the following syntax:

operatorType operator operatorName { } 

Here, operatorType can be one of the following:

• prefix
• infix
• postfix

Custom infix operators can also specify a precedence and an associativity:

infix operator operatorName { associativity left/right/none precedence} 

The possible values for associativity are left, right, and none. Left-associative operators associate to the left if written next to other left-associative operators of the same precedence. Similarly, right-associative operators associate to the right if written next to other right-associative operators of the same precedence. Non-associative operators cannot be written next to other operators with ...