This program provides a useful environment to write programs in pure
or typed lambda-calculus. Given a term, the program will compute and print
its normal form. This means that, unlike most functional languages, computation
is done under function abstractions (or lambdas).
This software might be used for teaching lambda-calculus or just to
play with it.
It has some interesting features :
Three modes of evaluation:
call-by-name with some sharing
call-by-name with no sharing
call-by-name and printing of each beta-reduction step or tracing of
It is implemented in Objective
Caml (a dialect of ML) so easily portable to many machines, even very
It is quite efficient. It uses a High-Order-Abstract-Syntax representation
of terms which help to benefit from ML management of closure. This is specially
optimised to give both reasonable performance in speed and memory. It's
possible to terminate computation of factorial 100 with a binary encoding
of natural numbers !
You can define terms (even using recursive definitions) or include
files. This gives enough modularity to write fairly large terms.
You can use a typing algorithm for system F (with or without inductive
type) to program more ``safely''.