Implement calc age with readMay
Implement 'Decoupling code' exsample
Implement 'Functors' example
Implement 'do-notation' example
Implement 'Dealing with two variables' example with pattern matching
Implement 'Dealing with two variables' example with do-notation
Implement 'Partial application' example with single fmap
Implement 'Partial application' example with fmap twice
Implement 'Applicative Functors' examples
Implement 'So we don't need monads?' example