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Here is the latest Caml Weekly News, for the week of January 13 to 20, 2009.

  1. React 0.9.0
  2. Rtime 0.9.0

React 0.9.0

Archive: http://groups.google.com/group/fa.caml/browse_thread/thread/88435fddcac27fbf#

Daniel Bünzli announced:
I'd like to announce the following module.

React is an OCaml module for functional reactive programming (frp). It
provides support to program with time varying values : applicative events and
signals. React doesn't define any primitive event or signal, this lets the
client chooses the concrete timeline.

React is made of a single, independent, module and distributed under the new
BSD license.

Project home page : http://erratique.ch/software/react

Although the code is feature complete and has been tested it has not been in
large scale programs yet. A stable 1.0.0 will be published once I feel we have
the right api.

Your reactions are welcome,

Daniel


P.S.
Various incarnations of frp (frtime, yampa, flapjax, ocamlrt, reactive) helped
to implement React, thanks to their authors for sharing their source.

P.P.S.
Here's the answer to the forthcoming question about how React compares to
ocamlrt. Following are the points I think are different and worth mentioning.
But as I don't claim to have a thorough understanding of how ocamlrt works
feel free to correct me or make additions. ocamlrt used to be located at
http://users.wpi.edu/~squirrel/repos/ocamlrt2 but recently vanished. The
version at http://code.google.com/p/ocamlrt seems to be an older one.

* React doesn't use the object system. ocamlrt uses it internally.

* React doesn't use any global data structures. Care is still needed in
  multithreaded environments (see docs), but React is more thread and modular
  friendly.

* React treats constant signals separately via smart constructors, they are
  not part of the dataflow graph.

* React uses weak pointers in the dataflow graph's forward dependencies and in
  the update queue to prevent space leaks. ocamlrt leaks.

* React uses client provided functions to test signal value equality. ocamlrt
  doesn't deal correctly with effectful signals. Correctly means no value
  change (according to equality), no update, no effect.

* React has most of pervasives' functions on ints, floats and booleans already
  lifted in specific modules that may be opened in a given context.

* React is (and will be) only a pure OCaml reactive runtime. Interfacing with
  primitive events, signals or real time is left to React's clients. In other
  words React corresponds to the functionality provided by the library fr of
  ocamlrt.

* React has a precise description of the combinators' semantic in the
  documentation.

* React doesn't depend on extlib.

* Performance ? I don't really know. Some aspects may make React faster :
  doesn't leak, doesn't use a global datastore (which involves a hashtable and
  universal types). Some aspects may make it slower : use of weak references,
  subtleties in signal creation, correct treatment of equality.

* Being inavailable ocamlrt seems to be a dead project.
			

Rtime 0.9.0

Archive: http://groups.google.com/group/fa.caml/browse_thread/thread/7538cbe5978c8dd2#

Daniel Bünzli announced:
Related to my previous annoucement is the following module.

Rtime is an OCaml module implementing timelines for React [1]. It manages time
stamp events, delayed events and delayed signals along timelines. The client
chooses the concrete timeline by providing an absolute notion of time. Running
the timeline at the appropriate pace is left to the client.

Rtime is made of a single module and depends on React. It is distributed under
the new BSD license.

Project home page : http://erratique.ch/software/rtime

Although the code is feature complete and has been tested it has not been in
large scale programs yet. A stable 1.0.0 will be published once I feel we have
the right api.

Your feedback is welcome,

Daniel

[1] available at http://erratique.ch/software/react
			

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zM

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Alan Schmitt