Support definitions for custom product types

[melvic-ybanez]

Let's just limit ourselves with the following for now:

1. Scala: class, case class and trait
2. Java: class
3. Haskell: record types

We can then use the assumption feature to declare instances:

case class Foo(name: String, age: Int)

assume foo: Foo

def myFoo: (Foo => String) => String

The output should be:

def myFoo: (Foo => String) => String =
  f => f(foo)