Department of Mathematics & Computer Science
|Credits: 15||Convenor: Dr. F. J. de Vries||Semester: 2|
|Assessment:||Coursework: 30%||Three hour exam in May/June: 70%|
Explanation of Pre-requisites
Students taking this module should have a sound knowledge of simple
discrete mathematics, such as that found in CO1011; and of basic
imperative and functional programming, such as that found in CO1003,
CO1004 and CO2008. In particular,
the module will make use of sets, functions, (equivalence) relations,
elementary (classical) logic, and mathematical induction. An
understanding of basic programming constructs such as loops,
conditionals, and assignments is required, but not necessarily large
scale programming. Knowledge of basic functional programming is also
required, but again, not on a large scale. Any student without such knowledge
will need to undertake background reading to become
familiar with the basic principles of functional and possibly object
oriented programming; however, the material in CO3008 is taught from
Syntax is the formal arrangement of symbols and words, often to create
a language; and all programming languages have a particular syntax.
Semantics is the study of meaning, and in this module we shall
be concerned with the meaning of programming languages. An example
will help. Consider if true then x:=3 else x:=4; and
if (true) x=3; else x=4; The syntax of the two statements is
clearly different, but Pascal and C(++) programmers will know that
their semantics should be the same. In this example, the semantics of
each statement is the ``effect on a computer at run time''. If you
would like to learn more about the ideas behind modern programming
languages, how they work, why they work, and gain a clear picture of
how high and low level languages interact, then this is the course for
All programming languages should have a clear syntax and semantics, from the low level of microprogramming in a CPU, right up to high level programming languages. In this course you will learn methods for giving a run-time semantics to various programming languages. The languages range from high level programming languages (such as Java, C, and Haskell) to intermediate languages (which resemble assembler). We shall see that we can give both high and low level semantics to the same language syntax, and show that any one of the semantic descriptions is equivalent to any other. The high level semantics describes how a large program executes by the step-by-step execution of smaller sub-programs, whose execution is easy to specify precisely. The low level semantics works by translation of a high level language into a low level language; the simpler low level language can also be executed simply and precisely.
You will also learn more about the notion of a type, which you will have met in previous programming courses, and how types can be used to reduce errors in program code. For example, Java was claimed to be type safe, which means that if a program compiles, certain run time errors cannot occur. In 1997, Java was shown to not be type safe, using ideas similar to those met in this module.
By the end of this module, you will have a very sound grasp of the
basic ideas on which modern programming languages are based, which
will be of benefit to your future understanding of software
Inductive definitions and proofs. Rule and structural
induction. Transition and evaluation semantics for an imperative
language. Proofs of deterministic computation and the equivalence of
the transition and evaluation semantics. An abstract machine for the
execution of the imperative language. A proof of machine correctness.
Eager (call-by-value) evaluation semantics of a functional language
with recursive function declarations and imperative features. Lazy
(call-by-name) evaluation semantics of the same language. An extension
of the functional language with abstractions and local
declarations. Further type checking and inference; algorithm W. The SECD
M. Hennessy, The Semantics of Programming Languages: An Introduction Using Structured Operational Semantics, Wiley, 1990 (out of print).
H. R. Nielson and F. Nielson, Semantics with Applications, Wiley, 1992.
C. Gunter, Semantics of Programming Languages, MIT Press, 1992.
B. Kirkerud, Programming Language Semantics, Thompson Computer Press, 1997.
J. Mitchell, Concepts in Programming Languages, Cambridge University Press, 2003.
M. Scott, Programming Language Pragmatics, Morgan Kaufmann, 2000.
D. Schmidt, The Structure of Typed Programming Languages, MIT Press, 1994.
R. D. Tennent, Semantics of Programming Languages, Prentice-Hall, 1991.
David Watt, The Syntax and Semantics of Programming Languages, Prentice Hall Computer Science.
The Formal Semantics of Programming Languages,
MIT Press, 1993.
Author: N. Rahman, tel: +44 (0)116 252 3902
Course notes, web page, study guide, worksheets, handouts, lecture
rooms with two OHPs, past examination papers.
Course questionnaires, course review.
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Last updated: 2003-09-23
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Author: N. Rahman, tel: +44 (0)116 252 3902