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Haskell

Key Concepts​

Saying what to compute rather than how sum . map (^2) . filter even Separating pure and inpure code: Int -> Bool vs Int -> IO Bool Functions as first-class citizens: map :: (a->b) -> [a] -> [b] Equational reasoning map f . map g = map (f . g)

Main Drawbacks​

  • Difficult to reason about efficiency
  • Limited tool support for developers
  • Requires ability to think abstractly

Java

Key OO features​

  • Objects: This we create using new
  • Classes: Specify what is in an object and what we can do to them
  • Encapsulation (methods and data together: Put the methods which act on the data in the class
  • Abstraction (and interfaces): Only worry about what methods do, not how they are implemented
  • Data hiding (restrict access to data: Make data private and the 'interface' methods public
  • Composition (stronger than aggregation): Objects can contain other objects - and use them to do the work
  • Inheritance(specialisation, reuse, 'is-a': Reuse things like JButton and JLabel behaviour
  • (Sub-type) Polymorphism (dynamic dispatch, late binding: Behaviour only known at runtime, also the reason that Lambdas can 'wrap up' a function
  • Generics (parametric polymorphism): Implemented using sub-type polymorphism

Everything is an object in Java. State is usually mutable Prefer iteration as being more efficient