OCaml Weekly News

We have the pleasure of celebrating the anniversary of Sputnik-1 by announcing the release of OCaml version 4.07.1.
This is a bug-fix release, see the list of changes below.

It is (or soon will be) available as a set of OPAM switches, and as a source download here:
https://caml.inria.fr/pub/distrib/ocaml-4.07/

Happy hacking,

– Damien Doligez for the OCaml team.

I'm happy to announce the release of ppx_yojson a rewriter for all of you out there working with Yojson. Version 0.1.0 provides an extension to write Yojson literal expressions in a more concise and readable way.

As an example, you can write:

let json = [%yojson {some_string = "string"; some_list = [1; 2; 3]}]

instead of:

let json =
  `Assoc
    [ ("some_string", `String "string")
    ; ("some_list", `List [`Int 1; `Int 2; `Int 3])
    ]

It's available on github and opam. There's more to come soon, including extensions for patterns and antiquotations. You can see the full list of features goals for the 1.0.0 here.

Hi, this week I cleaned-up and released 3 packages:

BER MetaOCaml N107 is a strict superset of OCaml 4.07.1 for ``writing programs that generate programs''. BER MetaOCaml adds to OCaml the type of code values (denoting ``program code'', or future-stage computations), and two basic constructs to build them: quoting and splicing. The generated code can be printed, stored in a file – or compiled and linked-back to the running program, thus implementing run-time code optimization. A well-typed BER MetaOCaml program generates only well-scoped and well-typed programs: The generated code shall compile without type errors. Staging-annotation-free BER MetaOCaml is identical to OCaml; BER MetaOCaml can link to any OCaml-compiled library (and vice versa); findlib and other tools can be used with BER MetaOCaml as they are, in their binary form.

BER MetaOCaml N107 is a superset of the just released OCaml 4.07.1. It also has a number of small improvements: better error messages, no longer needing parentheses when putting a sequence of statements in brackets, more convenient genlet, etc. It also has two notable additions: explicit lifting and new offshoring.

Explicit lifting is the explicit conversion of a value to the code, which, when compiled and run, (re-)produces that value. BER N107 supports explicit lifting of base-type values and lists, options, and, notably, arrays of liftable values. Explicit lifting is described in Section 3.2.1 of the MetaOCaml book.

The generated code, if simple enough, can be `offshored' – converted to the intermediate, imperative language which may then be transcribed to C, OpenCL, LLVM, etc. When generating computational kernels, the code is supposed to be simple enough, so it runs fast. One test case in MetaOCaml distribution shows how can one go about converting the intermediate code to C. Offshoring thus lets us treat a subset of OCaml as a new notation (syntax) for C.

BER MetaOCaml N107 should be available though OPAM, hopefully soon. In the meanwhile, it is available as a set of patches to the OCaml 4.07.1 distribution.
http://okmij.org/ftp/ML/ber-metaocaml-107.tar.gz
See the INSTALL document in that archive. You need the source distribution of OCaml 4.07.1.

For more explanations, please see
http://okmij.org/ftp/ML/MetaOCaml.html
as well as ChangeLog and NOTES.txt in the BER MetaOCaml distribution.

> I’m trying to create a simple client for Docker

You may be interested by the docker-api package (a new version should be released soon). You are welcome to submit PRs to add functions you care about.

Here is a sneak peek at some potential future features of the Ocaml compiler, discussed by their implementers in these Github Pull Requests.

• In error messages, print the source fragment responsible for the error
• Add infix operators for function composition