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

[Xavier Leroy <Xavier.Leroy@inria.fr>]

On 03/26/2011 02:12 AM, Lauri Alanko wrote:

> 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.

Don't put too much meaning in this distinction.  Basically, the
"language extensions" chapter describes most of the features that were
added since OCaml 1.00 back in 1995 (!), or that were present in 1.00
but considered a bit experimental then.

This said, only one of those extensions went away in the past (stream
pattern matching, as Martin Jambon recalled), and I don't see any of
the remaining extensions going away in the short to medium term.

However, some of those extensions are a little less "future-proof"
than the core of the language and are more likely to change in
slightly incompatible ways.  A prime example is recursive modules,
whose type-checking has changed a couple of times in the past (because
it walks a fine line between unsoundness and undecidability), breaking
some Caml code that uses recursive modules.

Perhaps, one day, the most stable "extensions" should be moved from
the "language extensions" chapter to the "Objective Caml language"
chapter, but this is just a matter of presentation.

Hope this clarifies the issue.

- Xavier Leroy