Welcome to CSC326F Programming Languages

Transcription

1 Welcome to CSC326F Programming Languages

2 Course info instructor: Neil Gower www: textbooks: none! If you want something to get you started: Thinking in Java (2E) by Bruce Heckel. ISBN or free at mindview.net Understanding Object-Oriented Programming with Java by Timothy Budd. ISBN Concepts of Programming Languages (5E) by Robert Sebesta. ISBN

3 Getting help check the web site ask your TA in tutorial post to discussion list TAs in the lab me, or ask before/during/after class

4 Evaluation 25% Assignments 30% Mid term 45% Final exam

5 Assignments to be completed individually electronic submission on ECF late policy: 2 grace days for the term for use in emergencies, don't waste them (there are no extensions)! if you are running out of time, hand in a working, tested version of a simpler program. re-marking: discuss with the marker first submit to your instructor

6 Course Introduction

7 Why study programming languages? increase vocabulary of programming constructs understand language manuals learn new languages more easily design new languages make good language selection choices

8 Turing thesis Anything that can be effectively computed can be computed by a Turing machine. There does not, and cannot exist a machine that can compute things a Turing machine cannot compute.

9 The simple Turing machine infinite tape divided into squares each square may contain a symbol from a finite alphabet finite number of squares with symbols read/write head always positioned at a particular square on the tape internal state finite number of states set of instructions (current state, current symbol, new state, new symbol, left right)

10 Choice of language is irrelevant? No matter what language you choose, you will be able to write a program that computes whatever you need it to (given enough time and memory). BUT some programs are easier to write in some languages than others.

11 Levels of languages machine language assembly language high level languages we are interested in high level languages

12 Classifying languages Languages can be distinguished by the features they offer and the computational paradigm they adopt. 1 st class citizens: directly supported by the language, do not require additional work from the programmer As in nature, classification is not always an all or none decision.

13 imperative Programming Paradigms computation as a sequence of actions Fortran, Algol 60, Pascal, C functional computation as application of functions to symbols Lisp, Scheme, ML logic programming computation as logical reasoning Prolog object-oriented computation as interaction between objects Smalltalk, C++, Java

14 What are we doing this term? Java Scheme More sophisticated Java C++

15 Java object-oriented programming objects are first class citizens James Gosling, early 90's. typically runs on a virtual machine programmer friendly

16 Topics in Java interfaces, inheritance, and polymorphism. information hiding iterators generic containers and exceptions abstract classes packages and access rules extending core Java classes

17 Scheme functional programming functions are first class citizens compact dialect of LISP, created mid 70's. The Scheme Programming Language by Kent Dybvig. ISBN Also available free from scheme.com

18 Topics in Scheme lists and trees recursion symbols and quotes symbolic algebra higher-order functions/code as data

19 C++ popular, modern OO language created by Bjarne Stroustrup at AT&T Bell Labs in mid 80's, though not standardized until 1998! good support for generic programming inherits many of the dangers of C

20 Topics in C++ values, references, and pointers generic programming defining and using templates

21 Generic Programming software can be decomposed into reusable components strong claim: make minimal assumptions about other components maximize flexibility does not require modification