SECD is an extremly simple virtual machine for functional programming.

This package provides a collection of different SECD implementations.

All they follow the wonderful book:

Peter Henderson, "Functional Programming: Application and Implementation", 1980, Prentice Hall

This package is useful for educational purposes or as a starting point for LISP implementation.

It is supplied with documentation - Reference manual, Tutorial, Implementation scheme, and SECD reference.

If you like the high level aspects of the functional programming, download this form of the package (~ 76K).

Download the full package SECD_Mania from here (~ 920K) or some selected (~ 185K) machines only.

Mirrors:

skelet.ludost.net - last version

skelet.hit.bg/SECD - previous version

Requirements: You must have FreePascal installed on your system.

If you use Debian Linux, simply type:

apt-get install fp-compiler binutils

If you use other Linux or other OS (WinXX, DOS), go to FreePascal home page for instructions.

Usage:

If you use Linux, download the package in some new directory, then type:

tar xzf SECD_0.8.tar.gz

or 

tar xzf BASE_0.8.tar.gz

Now you have the package sources. Read carefully the collection file, select some of the SECD machines and go to corresponding subdirectory. If you have selected some machine from the package - Files_2 as example, type:

cd Files_2
./make_all

Now you have some ready executable programs:

./self compiles compiler.lisp itself

./comp fname compiles LISP program from file fname.lisp

./secd fname executes compiled SECD code from file fname.secd

In 1941 Alonzo Church invented a mathematical notation called the lambda-calculus.

"The Calculi of Lambda Conversion" A. Church Princeton University Press 1941

The lambda-calculus was a mathematical system which modelled the computational view of functions. (There is also a set theoretic view of functions which turns out to be no use for computation - the reason why is left as an exercise for the mathematically gifted.)

Church had no intention of actually evaluating lambda-calculus expressions on a computer - which is hardly surprising given the date of his work. Nonetheless the lambda-calculus is the computational model of all functional programming languages. A functional programming language is just a lambda-calculus expression written in a different syntax - just as any imperative program is a Von Neumann machine program written in a different syntax.

John McCarthy invented the language LISP in 1960.

"Recursive functions of symbolic expressions and their computation by machine, Part I" J. McCarthy Communications Of The ACM, Vol. 3, No. 4, 1960

LISP is an acronym for "LISt Processing"; LISP was designed to make writing list processing programs easier. LISP was the world's first functional programming language.

In 1964 Peter Landin invented the SECD machine.

"The Mechanical evaluation of Expressions" P.J. Landin The Computer Journal Vol. 6 pp308-320 1964

The SECD machine is an "abstract machine" (i.e. it is a program rather than a piece of hardware). Landin used the SECD machine to evaluate lambda-calculus expressions. He also showed how programs written in ALGOL could be translated into the lambda-calculus.

The SECD machine has since been frequently used to produce prototype implementations of functional languages. For example Peter Henderson used it to implement his lazy dialect of LISP { LISPKIT LISP } and his specification language me-too.

In 1975 Gordon Plotkin published a paper that examines the relation between the Lambda Calculus and the SECD machine. The paper includes a proof that the semantics defined by the SECD machine is equivalent to a recursively defined function which implements applicative order evaluation of lambda terms.

Plotkin, Gordon D., "Call-By-Name, Call-By-Value, and the Lambda Calculus", Theoretical Computer Science, Vol 1, pp. 125-159, North-Holland, 1975.

In 1976 lazy evaluation, one of the most important and powerful concepts of modern functional programming, was independently invented by Peter Henderson & James Morris and by Dan Friedman & David Wise.

"A Lazy Evaluator" P. Henderson and J.H. Morris In : Conference Record of the Third ACM symposium on Principles of Programming Languages January 1976

"Cons should not evaluate its arguments" D.P. Friedman and D.S. Wise In : Automata Languages and Programming Third International Colloquium Eds. S. Michaelson and R. Milner Edinburgh University Press 1976

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