1. Programming Languages
CS 430/CS 530
Fall 2004
Professor Adams

2. Programming Languages
facilitate the expression and communication of ideas between people
have a narrower expressive domain than natural languages because they only communicate algorithmic ideas
enable communication of algorithms between people and computers
Think of all the ways I could tell you to “leave me alone” and the nuances of each. Narrower expressive domain doesn’t have those nuances.

3. Required definition of an Algorithm
An algorithm is an unambiguous, step-by-step procedure for solving a problem in a finite amount of time using a finite amount of space

4. Categories of Language Design Principles
Syntax
context-free grammar
Type systems and semantics
values that programs can manipulate
meaning of programs
Memory management
Exception handling

5. Memory Management static memory dynamic memory stack heap
lifetime of objects
techniques for garbage collection & storage reclamation

6. Exceptions unexpected input unexpected divide by zero
unexpected attempt to create a new block of space on the heap

7. Programming Paradigms
Imperative
Object-oriented
Functional
Logic (declarative) programming
Event-driven programming
Concurrent programming

8. Imperative Programming
Explicit series of steps
calculates, retrieves input, produces output
Procedural abstraction
assignments, loops, sequences, conditionals
Major imperative languages
Fortran (1954, IBM, John Backus), Cobol (Codasyl Committee), C (designed for and implemented on the UNIX operating system on the DEC PDP-11 by Dennis Ritchie) , C++, Ada

9. Object-Oriented Programming
Program is a collection of objects which pass messages to one another to transform their states
Object modeling, classification, inheritance are fundamental building blocks
Major OO languages
Smalltalk (Xerox PARC - Adele Goldberg & Alan Kay 1970’s), Java, C++, Eiffel

10. Functional Programming
Program is a collection of mathematical functions
input (domain)
result (range)
Functions interact & combine using
functional composition, conditionals, recursion
Major functional languages
Lisp (John McCarthy – M.I.T. – late 50’s), Scheme (block structure, lexical scoping, etc.), Haskell, ML

11. Logic (declarative) Programming
Program is a series of statements about what should happen rather than how it should be done
Expresses non-determinism
Major logic programming language
Prolog(Alain Colmerauer – Universite d’Aix Marseilles – 1972)

12. Event-driven Programming
Program is a continuous loop that responds to unpredictably ordered events
Events originate from
user actions (mouse clicks or keystrokes)
sensors on a robot
Major event-driven languages include
Visual Basic, Java

13. Concurrent Programming
Program is a collection of cooperating processes
Concurrent Programming Languages
SR, Linda, High Performance Fortran