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

[Martin Jambon <martin.jambon@ens-lyon.org>]

On 03/25/11 21:30, Steven Shaw wrote:
> Perhaps it doesn't mean much when there's only one implementation of
> Objective Caml. However, if a second implementation came along then I
> guess it may only implement the core language without extensions (and
> still be considered a valid "Objective Caml").

The "language extensions" section of the manual describes features that
are perfectly usable but may be gone in the next release of the official
Objective Caml distribution (compilers etc.).

For example, there used to be a special syntax for pattern matching
against streams (Stream module). It was removed but can still be used by
preprocessing .ml files with camlp4 or camlp5.

Currently the least esoteric features that are commonly used among these
"language extensions" are in my opinion:

- assert
- integer literals for int32 and int64
- lazy expressions (but not lazy patterns)
- char range patterns
- local open (new in 3.12)
- record notations (new in 3.12)

It is easy to see workarounds if these features were to disappear from
the official implementation because they are mostly syntax. Not so sure
about the other extensions.


Martin