1. Lecture on Programming Languages
Chapter#5

2. Programming Paradigms/Models
Paradigm defines a model or way of programming
We will discuss the following three paradigms
Imperative/Procedural Paradigm
Declarative Paradigm
Object Oriented Paradigm

3. The evolution of programming paradigms

4. The composition of a typical imperative program or program unit

5. Procedural Units Local versus Global Variables
Formal versus Actual Parameters
Passing parameters by value versus reference
Procedures versus Functions

6. The flow of control involving a procedure

7. Example of procedure written in C language

8. Executing the procedure Demo and passing parameters by value

9. Executing the procedure Demo and passing parameters by reference

10. Object Oriented Paradigm
In this approach all real world things are considered as an object. Each object has a certain set of qualities/ attributes and each object can perform some job/method. Thus if I have an object CAR then Car has its color, engine#, make, model etc as attributes and its methods can be drive(), stop() etc
Examples include C++, Java etc

11. Declarative Programming Approach
It emphasizes the question “What is the problem?” rather than “What algorithm is required for solving the problem?” Here a general problem solving approach is developed that can solve a number of problems. These languages are difficult to design and are special purpose by nature
PROLOG (Programming LOGic) is an example

12. Figure 6.25 Resolving the statements (P OR Q), (R OR ¬Q), ¬R, and ¬P

13. Declarative Programming
Resolution: Combining two or more statements to produce a new statement (that is a logical consequence of the originals).
Example: (P OR Q) AND (R OR Q) resolves to (P OR R)
Resolvent: A new statement deduced by resolution
Clause form: A statement whose elementary components are connected by the Boolean operation OR
Unification: Assigning a value to a variable so that two statements become “compatible.”

14. Prolog Fact: A Prolog statement establishing a fact
Consists of a single predicate
Form: predicateName(arguments).
Example: parent(bill, mary).
Rule: A Prolog statement establishing a general rule
Form: conclusion :- premise.
:- means “if”
Example: wise(X) :- old(X).
Example: faster(X,Z) :- faster(X,Y), faster(Y,Z).