[cwn] Attn: Development Editor, Latest OCaml Weekly News
Alan Schmitt
alan.schmitt at polytechnique.org
Tue Jun 3 04:13:20 PDT 2014
Hello,
Here is the latest OCaml Weekly News, for the week of May 27 to June 03, 2014.
1) PG'OCaml 2.0
2) Why AVL-tree?
3) Other OCaml News
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1) PG'OCaml 2.0
Archive: <https://sympa.inria.fr/sympa/arc/caml-list/2014-05/msg00174.html>
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** Dario Teixeira announced:
I'm happy to announce version 2.0 of PG'OCaml, a library offering type-safe
access to PostgreSQL databases for OCaml applications.
This version no longer depends on Batteries, which hopefully will entice more
Core users to give it a spin. Below is the list of the remaining changes,
straight from the changelog:
* Dario Teixeira and Jacques-Pascal Deplaix: fixing issues with arrays.
This requires all array types to change from 'a array to 'a option array,
which breaks backward compatibility.
* Dario Teixeira's patch making PostgreSQL's NUMERIC type be converted
to/from OCaml strings. This change is not backward's compatible,
requiring a bump in the major version number (though there seems
to be no actual code in the wild relying on the previous behaviour).
* Dario Teixeira's patch adding function 'uuid', which exposes the
unique connection handle identifier.
* Jacques-Pascal Deplaix's patches adding 'catch', 'transact', 'alive',
'inject', and 'alter' functions.
Note that a couple of changes break backward compatibility, hence the new
major version number. These changes were required to fix some long-standing
issues, so I trust you'll be understanding.
This new release should be hitting OPAM soon. Alternatively,
you can grab the source from the project's homepage:
<http://pgocaml.forge.ocamlcore.org/>
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2) Why AVL-tree?
Archive: <https://sympa.inria.fr/sympa/arc/caml-list/2014-06/msg00010.html>
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** Yoriyuki Yamagata asked and Xavier Leroy replied:
> Just from the curiosity, why balanced binary trees used in Set and
> Map are AVL-trees, not their alternative, say, red-black trees? Is
> there a deep reason for it, or just a historical one?
At the time Set was written, no efficient algorithms for whole-set
operations (union, intersection, difference, etc) were known for
red-black trees. I'm not sure they are known today.
As for performance of insert/lookup operations, Jean-Christophe
Filliâtre has measurements showing that OCaml's 2-imbalance AVL trees
perform better than red-black trees. It all depends on your ratio of
insertions to lookups, of course. But the 2-imbalance trick makes a
big difference with textbook AVL trees.
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3) Other OCaml News
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** 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 <http://planet.ocaml.org/>.
OCaml 4.02.0-beta:
<http://wodi.forge.ocamlcore.org/2014/05/31/ocaml-4.02beta.html>
PG'OCaml 2.0 released:
<https://forge.ocamlcore.org/forum/forum.php?forum_id=901>
PG'OCaml 2.0 has been released:
<http://rwmj.wordpress.com/2014/05/28/pgocaml-2-0-has-been-released/>
Announcing PG'OCaml 2.0:
<http://nleyten.com/post/2014/05/28/Announcing-PG-OCaml-2.0>
Full Time: Software Developer (Functional Programming) at Jane Street in New York, NY; London, UK; Hong Kong:
<http://jobs.github.com/positions/0a9333c4-71da-11e0-9ac7-692793c00b45>
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