Ways of structuring programs.
PROCEDURAL
Programs as sequences of instructions, organised into procedures.
OBJECT-ORIENTED
Programs as objects combining data and the operations on it.
FUNCTIONAL
Programs as compositions of functions, avoiding changing state.
DECLARATIVE
Describing what is wanted rather than how to obtain it.
WHAT MOST MODERN LANGUAGES ARE
Multi-paradigm, supporting several approaches.
WHAT OBJECT ORIENTATION PROVIDES
- Encapsulation: data and behaviour together
- Inheritance: sharing behaviour
- Polymorphism: different types used uniformly
WHAT IT IS CRITICISED FOR
Deep inheritance hierarchies becoming rigid and difficult to follow.
WHAT TO PREFER
Composition over inheritance.
WHAT FUNCTIONAL PROGRAMMING PROVIDES
Predictability, since functions depending only on inputs are easy to reason about and test Easier parallelism, since shared changing state is what makes it hard
WHAT A PURE FUNCTION IS
One with no side effects, returning the same result for the same inputs.
WHAT TO ADOPT REGARDLESS OF LANGUAGE
Minimising changing shared state, and preferring pure functions where practical.
