Hello

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

React 0.9.0

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

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#

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

Using folding to read the cwn in vim 6+

Here is a quick trick to help you read this CWN if you are viewing it using vim (version 6 or greater).

:set foldmethod=expr

:set foldexpr=getline(v:lnum)=~'^=\\{78}$'?'<1':1

zM

If you know of a better way, please let me know.

Old cwn

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Alan Schmitt