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Here is the latest OCaml Weekly News, for the week of November 11 to 18, 2014.

  1. containers 0.5
  2. OCaml opportunities in London
  3. opam-query 1.0
  4. Go Oracle like facility for Ocaml?
  5. Other OCaml News

containers 0.5


Simon Cruanes announced:
I'm pleased to announce the release of containers-0.5, an extension to
OCaml's standard library. Since my initial announce on this list,
containers has grown and stabilized, but remained modular and
lightweight. This release also brings compatibility with `-safe-string`[1]
which makes it depend on `base-bytes`. It now features modules that
extend `Map`, `Hashtbl`, a lightweight S-expression parser[2], new
functions in existing modules and bugfixes. There is also a new
sub-library, `containers.pervasives`, that provides a single
`CCPervasives` module that can be opened to alias `List`, `Option`, etc.
to their counterparts.

Containers should be especially useful for programmers who don't want to
depend on bigger libraries such as Core or Batteries, programmers who target
js_of_ocaml, or who just want to copy-paste a few useful
modules/functions into their own `` file[3].

Containers is on opam, and its source code (BSD licensed) is
on github: . The online
documentation can be found here: .

I would also like to thank the other contributors : jpdeplaix, drup,
nicoo, and whitequark.



[1] if not, please fill a bug report. Please.
[2] CCSexp is only one module, with a streaming interface, and therefore
    less comprehensive than Sexplib. Still a bit experimental atm.
[3] I don't judge :-)

OCaml opportunities in London


Shayne Fletcher continued the thread from last week:
To clarify, this position is in fact offered by Bloomberg.
As you may be aware, Bloomberg has licensed LexiFi technology for
financial contract representation. To learn more about the use of
LexiFi's technology in the Bloomberg Professional Service, see We are seeking developers to work on this
effort among other challenges.
As this community is characterized by transparency, we consider it an
unfortunate mistake this information was held back and unreservedly
We are very excited at the prospect of growing our teams of OCaml
developers in both London and New York and strongly encourage those
among you interested in a career in financial technology to reach out
to us!

opam-query 1.0


Peter Zotov announced:
I'm glad to announce the release of opam-query 1.0.
It will be available in OPAM shortly.

opam-query is a tool that allows querying the OPAM package
description files from shell scripts, similar to `oasis query`.

Most interestingly, it can be used to automate releasing
OPAM packages. For example, the following Makefile snippet
allows to release packages by merely changing the `version:'
field and running `make release'. (Right now, only GitHub URLs
are supported by --archive.)

    VERSION      = $(shell opam query --version)
    NAME_VERSION = $(shell opam query --name-version)
    ARCHIVE      = $(shell opam query --archive)

      git tag -a v$(VERSION) -m "Version $(VERSION)."
      git push origin v$(VERSION)
      opam publish prepare $(NAME_VERSION) $(ARCHIVE)
      opam publish submit $(NAME_VERSION)
      rm -rf $(NAME_VERSION)

    .PHONY: release

Please see the README[1] for complete documentation.


Go Oracle like facility for Ocaml?


Kenneth Adam Miller asked and Gabriel Scherer replied:
> If anybody knows what Go's oracle is you'll know that its a great
> accelerator for your time; it allows expressive and meaningful searches to
> be done over a source repository. It's fast and dead useful. Opengrok is
> much the same, but to a lesser extent (having links is nice, but not quite
> as powerful as oracle, I could be wrong).
> Is there anything like this for OCaml?

(One can find a description of Go oracle's design in
and its user manual in

The ecosystem of OCaml tooling is not as refined as Go's (but
contributions are welcome). There is no centralized tool provider with
a common interface, but several contributors have developped separate
tool to anayze different aspects of OCaml programs:

- ocamlspotter:
- ocp-index:
- pfff:
- merlin:

These tool provide a relatively complete coverage of the information
that can easily be retrieved from the typedtree of a program (>=4.01
versions of the OCaml compiler have the option to generate a reified
typedtree for external tools): the occurences of a declared/defined
name, the definition place of a name, the type of an expression, etc.
As far as I'm aware, there is not much in the direction of the more
advanced static analysis feature Go's oracle supports: points-to
information, "who may update this mutable field", etc. I'm not
familiar with Pfff's capabilities, it may be the more advanced in this

(There is also more experimental work going on, for example Thomas
Blanc's work on static analysis of exception flow at OCamlPro: )

I think merlin is the best-positioned tool to deal with
partially-incorrect files (typical of an edition session) and
incrementality. It also incorporates some query/analysis feature, but
it's unclear whether those should grow inside a monolithic tool (eg.
it could encompass the current feature set of ocp-index and
ocamlspotter, if it does not already), or rather try to communicate
with external analysis/query plugins. It also interacts with existing
editors through a reasonable query-answer interface, but does not
provide a direct command-line interface (anyone interested in this
could work on it, it may be relatively easy to implement).

There are fairly orthogonal aspects to a "answering questions about
programs" toolbox, among which:
1) user-interface, interactive use, and interface with existing editors
2) support for incrementality and robustness under partially-incorrect files
3) knowledge of what the "project", or whole program, is; which
dependencies are required to understand the work? (build system
4) implementation of various program analyses and transformations

Is it possible to provide them in separate programs and have them
interact to form a useful whole? Or would it be easier, faster and
more robust to implement them all in a monolithic program? What are
the necessary interdependence between these aspects and what interface
should them provide to each other?

Other OCaml News

From the ocamlcore planet blog:
Thanks to Alp Mestan, we now include in the OCaml Weekly News the links to the
recent posts from the ocamlcore planet blog at

How to choose a teaching language:

Dimensional Analysis in OCaml:

Ocaml teaching resources:

"Good news, everyone!" - teaching page is live!:

Old cwn

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Alan Schmitt