CHANGE LOG

Version 1.0: 

	First public version

Version 1.1:

	Removed ad-hoc restriction on pattern instantiation.

Version 1.2:

	Added recursion.

Version 1.3:

	Fixed a mistake in the algorithm's rules and code.
	( judge term A<:Top F<:A->A a:A f:F |- f(a):A; would fail.)

Version 1.4:

	Ported to Modula-3 v.2.0.

	Fixed several mistakes in the typing and operational semantics
	rules (thanks to Georges Gonthier), although the program code was
	correct.

	Fixed a mistake in the rules and operational semantics of fold
	(thanks to Mario Coppo and Mariangiola Dezani). The program is
	unchanged; an expression fold(:Y)(a) where the environment
	contains Y<:Y1, Y1<:Y2, ..., Yn<:Rec(X)B is now seen as an
	abbreviation for fold(:Rec(X)B)(a).

Version 1.5:

	Found a problem with free variables in actions (thanks to Florian
	Matthes). (let t = top; syntax term ::= ... ¬T¬ => t;
	fun(t:Top)T; captured t.) Note that the mechanism described in
	Section 3.4 is not involved in this situation. This situations is
	now reported as an error; existing examples were not affected.

	Added a command to activate the subtyping rule for bounded
	quantifiers proposed by Giuseppe Castagna:
		E |- AÕ<:A   E,X<:Top |- B<:BÕ   
		=>    E |- All(X<:A)B <: All(X<:AÕ)BÕ

Version 1.6:

	Ported to SRC Modula-3 v3.6 by Allan Heydon (heydon@pa.dec.com).