In this chapter, you will learn about a particular type of functional reference. First, let’s see define functional reference: reference means you can access and/or modify part of the values, and functional means that the flexibility and composability of functions are assured while accessing these parts.
Lenses are a type of functional reference, implemented in Haskell by the lens library
, that represent a first-class getter and setter. With a lens, you can do the following things:
Access a subpart
Alter ...
