The Jim Interpreter

A small-footprint implementation of the Tcl programming language.

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WHAT IS JIM?
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Jim is a small footprint implementation of the Tcl programming language
written from scratch. Currently Jim Tcl is very feature complete with
an extensive test suite (see the tests directory).
There are some Tcl commands and features which are not implemented
(and likely never will be), including traces and Tk. However,
Jim Tcl offers a number of both Tcl8.5 and Tcl8.6 features ({*}, dict, lassign,
tailcall and optional UTF-8 support) and some unique features.
These unique features include [lambda] with garbage collection, a general GC/references
system, arrays as syntax sugar for [dict]tionaries, object-based I/O and more.

Other common features of the Tcl programming language are present, like
the "everything is a string" behaviour, implemented internally as
dual ported objects to ensure that the execution time does not reflect
the semantic of the language :)

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WHEN JIM CAN BE USEFUL?
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1) Jim provides the ability to write scriptable applications without needing
to link your application with a big system. You can include the Jim source 
directly in your project and use the Jim API to write the glue code that makes 
your application scriptable in Jim, with the following advantages:

- Jim is not the next "little language", but it's a Tcl implementation.
  You can reuse your knowledge if you already have Tcl skills, or enjoy
  the availability of documentation, books, web resources, ...
  (for example check my online Tcl book at http://www.invece.org/tclwise)

- Jim is simple with 14k lines of core code. If you want to adapt it you can hack
  the source code to meet the needs of your application. It makes you
  able to have scripting by default, and avoid external dependencies.

  Having scripting support *inside*, and in a way that a given version
  of your program always gets shipped with the given version of Jim, you can
  write part of your application in Jim itself. This is similar to Emacs/Elisp
  or Gimp/Scheme, where both of these applications have the interpreter inside. 

- Jim is Tcl, and Tcl looks like a configuration file if you want. So
  if you use Jim you also have a flexible syntax for your config file.
  This is a valid Tcl script:

     set MyFeature on
     ifssl {
       set SslPort 45000
       use compression
     }

  It looks like a configuration file, but if you implement the [ifssl]
  and [use] commands, it's a valid Tcl script.

- Tcl scales with the user. Not all know it, but Tcl is so powerful that
  you can reprogram the language in itself. Jim support this feature
  of the Tcl programming language. You can write new control structures, and
  use the flexible data types it offers (Lists are a central data structure,
  with Dictionaries that are also lists). Still, Tcl is simpler for the
  casual programmer, especially when compared to other languages offering
  small footprint implementations (like Scheme and FORTH).

- Because of the Tcl semantic (pass by value, everything is a command
  since there are no reserved words), there is a nice API to glue
  your application with Jim. See under the Jim Tcl manual for more detail.

- Jim is supported. If you need commercial software, contact the original author
  at 'antirez@gmail.com' or the current maintainer at 'steveb@workware.net.au'.

2) The other "field" where Jim can be useful is obviously embedded systems.

3) We are working to make Jim as feature-complete as possible. Thanks to
   dynamically loaded extensions it may stay as small as it is today
   but able to do interesting things for you. So it's possible that
   in the future Jim will be an option as a general purpose language.
   But don't worry, there is already the mainstream Tcl implementation
   for this :).

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HOW BIG IS IT?
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Jim with the default extensions configured and compiled with -Os is about 130k.
Without any extensions, it is about 85k.

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HOW FAST IS IT?
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Jim is, in most code, faster than Tcl7.6p2 (latest 7.x version),
and slower than Tcl 8.4.x. You can expect pretty decent performance
for such a little interpreter.

If you want a more precise measure, there is 'bench.tcl' inside this
distribution that will run both under Jim and Tcl, so just execute
it with both the interpreters and see what you get :)

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HOW TO COMPILE
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Jim was tested under Linux, FreeBSD, MacosX, eCos, QNX, Windows XP (mingw, MVC).

To compile Jim itself try:

  ./configure
  make

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EXTENSIONS
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Many optional extensions are included. Some are C extensions and others are pure Tcl.
Form more information, try:

  ./configure --help

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HOW TO EMBED JIM INTO APPLICATIONS
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See the "examples.api" directory

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HOW TO WRITE EXTENSIONS FOR JIM
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See the extensions shipped with Jim, jim-readline.c, jim-clock.c, glob.tcl and oo.tcl

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COPYRIGHT and LICENSE
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Unless explicitly stated, all files within Jim repository are released
under following license:

/* Jim - A small embeddable Tcl interpreter
 *
 * Copyright 2005 Salvatore Sanfilippo <antirez@invece.org>
 * Copyright 2005 Clemens Hintze <c.hintze@gmx.net>
 * Copyright 2005 patthoyts - Pat Thoyts <patthoyts@users.sf.net>
 * Copyright 2008 oharboe - Øyvind Harboe - oyvind.harboe@zylin.com
 * Copyright 2008 Andrew Lunn <andrew@lunn.ch>
 * Copyright 2008 Duane Ellis <openocd@duaneellis.com>
 * Copyright 2008 Uwe Klein <uklein@klein-messgeraete.de>
 * Copyright 2008 Steve Bennett <steveb@workware.net.au>
 * Copyright 2009 Nico Coesel <ncoesel@dealogic.nl>
 * Copyright 2009 Zachary T Welch zw@superlucidity.net
 * Copyright 2009 David Brownell
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE JIM TCL PROJECT ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * JIM TCL PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and documentation
 * are those of the authors and should not be interpreted as representing
 * official policies, either expressed or implied, of the Jim Tcl Project.
 */
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HISTORY
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"first Jim goal: to vent my need to hack on Tcl."

And actually this is exactly why I started Jim, in the first days
of January 2005. After a month of hacking Jim was able to run
simple scripts, now, after two months it started to be clear to
me that it was not just the next toy to throw away but something
that may evolve into a real interpreter. In the same time
Pat Thoyts and Clemens Hintze started to contribute code, so that
the development of new core commands was faster, and also more
people hacking on the same code had as result fixes in the API,
C macros, and so on.

Currently we are at the point that the core interpreter is almost finished
and it is entering the Beta stage. There is to add some other core command,
to do a code review to ensure quality of all the parts and to write
documentation.

We already started to work on extensions like OOP, event loop,
I/O, networking, regexp. Some extensions are already ready for
prime time, like the Sqlite extension and the ANSI I/O.

------------------------------------------------------------------------------
Thanks to...
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- First of all, thanks to every guy that are listed in the AUTHORS file,
  that directly helped with code and ideas. Also check the ChangeLog
  file for additional credits about patches or bug reports.
- Elisa Manara that helped me to select this ill conceived name for
  an interpreter.
- Many people on the Tclers Chat that helped me to explore issues
  about the use and the implementation of the Tcl programming language.
- David Welton for the tech info sharing and our chats about
  programming languages design and the ability of software to "scale down".
- Martin S. Weber for the great help with Solaris issues, debugging of
  problems with [load] on this arch, 64bit tests.
- The authors of "valgrind", for this wonderful tool, that helped me a
  lot to fix bugs in minutes instead of hours.


----
Enjoy!
Salvatore Sanfilippo
10 Mar 2005


