Znatz questions

• What does these square brackets in Haskell?
• What actually $ function does in haskell? [duplicate]
• Why can I omit the constructor when referring to newtype wrapped number types?
• What is the rule of the order of multiple type variables in haskell?
• How does Haskell hide data constructor?
• How to upgrade Ruby to 2.0
• Simple examples to illustrate Category, Monoid and Monad?

Znatz answers