Paradigms (Cambridge (CIE) A Level Computer Science): Revision Note

Low-level

Closest to machine code, using mnemonics to directly control hardware

- Direct memory access
- Register manipulation
- Hardware-specific instructions

x86 Assembly, ARM Assembly

Imperative (Procedural)

Tells the computer how to perform tasks using sequences of commands

- Step-by-step instructions
- Use of loops, conditions
-Procedures/functions

C, Pascal, Python (procedural)

Object-Oriented

Models real-world entities using objects that combine data and behaviour

- Classes and objects
- Encapsulation, inheritance, polymorphism
- Modularity

Java, C++, Python (OOP)

Declarative

Describes what should be done, not how to do it

- Rule-based or logic-based
- No explicit control flow
- Focus on outcomes/results

SQL, Prolog, Haskell

Procedural

- Clear flow of control (top to bottom)
- Efficient for simple tasks
- Easy to implement algorithms
- Strong step-by-step logic

- Becomes hard to manage in large programs
- Poor modularity can lead to redundancy
- Not ideal for complex state-based systems

Object-Oriented

- Enhances modularity with encapsulation
- Real-world modelling via objects
- Code reuse through inheritance
- Polymorphism for flexible interfaces

- Can become overly complex
- Slower due to object overhead
- Misuse leads to bloated hierarchies
- Not ideal for every problem

Low-Level (Assembly)

- Complete control over hardware
- Highly optimised for performance
- Transparent view of machine operations

- Steep learning curve
- Hardware-specific, not portable
- Manual memory management is error-prone
- Difficult to debug/scale

Declarative

- Focuses on the result rather than the process
- Concise and expressive
- Suitable for complex logic or rule-based problems (e.g. AI, SQL queries)

- Harder to learn for beginners
- Less control over program flow
- Not suited for all types of problems
- Debugging can be challenging due to abstraction