A new beta of Gambit-C 4.0 is now available in source form at this address:

http://www.iro.umontreal.ca/~feeley/gambc40b15.tar.gz

Here's what's new:

- Threads are now structures that can be subtyped. The special form "define-type-of-thread" can be used to define a subclass of thread. The procedure thread-init! must be used to initialize derived threads. For example

(define-type-of-thread mythread myfield )

(define t (make-mythread 999)) (thread-init! t (lambda () (pp (mythread-myfield (current- thread))))) (thread-start! t) ; prints 999

- Each thread now has a mailbox. The procedure (thread-send thread obj) adds obj to the end of the thread's mailbox and (thread-receive [timeout [timeout-val]]) retrieves the oldest message in the current thread's mailbox.

- The "ring" example has been reimplemented with mailboxes. A "distributed computing" example has been added to show how mailboxes and object serialization can be used to implement a distributed computing system similar to Termite (see http://lambda-the-ultimate.org/node/view/841).

- Improvements to compiler: - Linking now accesses C files produced by the compiler in the current directory (where the compiler put them!) - Fixed variable conflict problem when using -debug option. - Performs safe specialization of (equal? X Y) to (eq? X Y) when X or Y is a fixnum, boolean, empty list, etc - Fixed inlining problem with cadar and friends (sigh). - Better expansion of +, -, *.

- For process ports: - Added directory: setting for open-process. - The executable of open-process is now searched using "PATH". - Added (process-pid port) and (process-status port [default-value]).

- A socket opened with open-tcp-client opens the connection in the background. Any connection error is reported at the first read or write on the port.

- Added (timeout->time timeout).

- Added (host-name) and (user-name).

- Added X!Y to the infix syntax.

- Fixed bug in quasiquotation of an improper list constant.

- Improved performance of symbol and keyword hash tables when many symbols and keywords are interned (e.g. "read"ing a file with a long list of symbols).

- Added (make-uninterned-symbol name [hash]) and (make-uninterned-keyword name [hash]).

- Improved hashing function in equal?-hash.

- The procedure make-table now honors the size: setting which sets the initial size of the table.

- Fixed a bug in serialization/deserialization of closures and continuations referring to code that accesses a global variable that has not been defined in the deserialization environment.

- Added Windows implementation of open-process, file-info and file- exists.

- Cleanup of lib/os.h and configure script to improve portability. Gambit now compiles cleanly on Mac OS X, Linux, Solaris, HP-UX, MinGW, and cygwin (and probably many other systems).

- Fixed cygwin bug in (copy-file source dest) when the files are binary.

- Improved nonblocking I/O on Windows. Now I/O on sockets, files, and processes only block the thread that requested the I/O.

- Fixed bug on MinGW which caused REPL I/O to be directed to an invisible console.