Introduction

The Tcl language has a very simple and regular syntax. If you approach it in the right way, i.e. if you don't "think in another language" while you use it, you can learn it in just a few days. Tcl stands for "Tool Command Language" to denote the fact that Tcl is designed from the ground up to be embeddable in applications, like E-lisp for Emacs or Visual Basic for Word. It also has a clean and well documented interface to C, which makes it easy to add extensions to it that provide new commands.

Tk is the most popular of the many extensions to Tcl: it is a graphical toolkit that allows you to write windowing applications at a very high level. Try writing the "hello world" program in your favourite GUI toolkit environment: in many cases this takes several pages of code. In Tk you can do it in two lines, like this:

    button .hello -text "Click me!" -command {puts "hello world!"}
    pack .hello

On top of that, Tcl and Tk are available for free in source form and you can modify and embed them in your applications without having to pay royalties.

Books and online learning resources

• John Ousterhout, Tcl and the Tk toolkit.
  This is the one conventionally referred to as "the Tcl book", written by the creator of the language. It is exceptionally clear and a pleasure to read. You don't want to be without it if you are going to use Tcl at all. It is not a reference manual: the reference documentation is contained in the man pages (written by the same author) that come with the Tcl distribution.

• Brent Welch, Practical Programming in Tcl and Tk.
  This is a good example-oriented book full of useful program fragments. You'll learn not only the language but also an array of useful techniques.

• Don Libes, Exploring Expect.
  This book is not about Tcl but about a wonderful tool called Expect which in turn can be programmed in Tcl. Expect, which really is well worth exploring, allows you to automate interactive programs. The book also teaches you Tcl in passing.

If you're not ready to go out and buy a book yet, try out Tcl and Tk for yourself! They may already be on your system. The best introduction is the widget tour by Andrew Payne, a set of short script examples that can be run interactively; you modify the source code and the program's behaviour changes dynamically. It is available in precompiled form for many architectures.

If you just want to read an introduction to Tcl/Tk here on the Web, try this one by David Martland.

Links

• The official page of Tcl/Tk Project At Sun Microsystems Laboratories
• The Tcl FAQs in hypertext format.
• The Tcl/Tk resources, which let you register code, design ideas, job offers so that others know about it.
• The Tcl WWW Info, which includes pointers to the FAQ files and to lots of other stuff.

And here are a few home pages of people who've got something to do with Tcl/Tk:

• John K. Ousterhout, inventor of Tcl/Tk.
• Brent Welch, author of the exmh mail interface and of the Practical Programming book mentioned above.
• Ioi Kim Lam, author of Tix, the Tk Interface Extension, a set of visually pleasing mega-widgets. Check out his outstanding page of links, too!

My own stuff

I am a programmer in the Medusa project at Olivetti Research Limited and I use Tcl/Tk to write distributed multimedia applications.

My paper "Writing Tcl programs in the Medusa applications environment" was presented at the 2nd Tcl/Tk workshop in 1994. The slides for that presentation are available in Postscript (2 per page) or in Powerpoint format.

At the Tcl/Tk 1995 workshop I presented another paper, "Taming the complexity of distributed multimedia applications", which I co-authored with Rob Walker. The slides are here, in Postscript 2-up or in Powerpoint.

And this is my detailed report on the Tcl/Tk 1995 workshop, again co-authored with Rob Walker.

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