1.scala

import shapeless._

// A pair of ordinary case classes ...
case class Address(street : String, city : String, postcode : String)
case class Person(name : String, age : Int, address : Address)

// Some lenses over Person/Address ...
val nameLens     = lens[Person] >> 'name
val ageLens      = lens[Person] >> 'age
val addressLens  = lens[Person] >> 'address
val streetLens   = lens[Person] >> 'address >> 'street
val cityLens     = lens[Person] >> 'address >> 'city
val postcodeLens = lens[Person] >> 'address >> 'postcode

scala> val person = Person("Joe Grey", 37, Address("Southover Street", "Brighton", "BN2 9UA"))
person: Person = Person(Joe Grey,37,Address(Southover Street,Brighton,BN2 9UA))

scala> val age1 = ageLens.get(person)               // Read field, note inferred type
age1: Int = 37

scala> val person2 = ageLens.set(person)(38)        // Update field
person2: Person = Person(Joe Grey,38,Address(Southover Street,Brighton,BN2 9UA))

scala> val person3 = ageLens.modify(person2)(_ + 1) // Transform field
person3: Person = Person(Joe Grey,39,Address(Southover Street,Brighton,BN2 9UA))

scala> val street = streetLens.get(person3)         // Read nested field
street: String = Southover Street

scala> val person4 = streetLens.set(person3)("Montpelier Road")  // Update nested field
person4: Person = Person(Joe Grey,39,Address(Montpelier Road,Brighton,BN2 9UA))