What is the primary building block of your programs?

• Functional

  • Mostly functional with imperative where needed. Managing what state is intrinsic, necessary, and appropriate.
  • The Basic building block is a referentially transparent function. A function which returns the same output per given input every time.
  • The environment does not affect the output of a referentially transparent function so we can reason about it independently.

• Imperative

  • The Basic building block is a stateful action (object in OO).
  • Without environmental knowledge it’s impossible to reason about and test.
  • You must be able to control the environment in which the action occurs to know if it’s being done right.
  • The environment is an implicit parameter on the action. Making the environment explicit makes it referentially transparent.