[Caml-list] What are "Language extensions"?

[Lauri Alanko <la@iki.fi>]

In the O'Caml reference manual, the actual language specification is
split into two parts, "The Objective Caml language" and "Language
extensions". I'm curious as to what this division indicates about the
status of different features of the language. The manual itself
doesn't help much, since the extensions chapter only opens with:

	This chapter describes language extensions and convenience
	features that are implemented in Objective Caml, but not
	described in the Objective Caml reference manual.

In other words, "this chapter is for the stuff that isn't in the
previous chapter". Not very informative.

What, then, does it mean for something to be an extension instead of a
part of the "basic" language? Is it about backwards compatibility
(e.g. the basic language is guaranteed to work with every 3.x
release)? Or about forward compatibility (e.g. some extensions might
not be supported in a future 3.x release)? Or about stability? Will
some of the extensions eventually be incorporated into the "basic"
language?

The structure of the manual clearly implies that I as a programmer
should take into account that a feature is an "extension". I just
have no idea what I should do with that knowledge.


Lauri