TCL - Portable Scripting and CGI

Tcl, Tool Command Language (pronounce tickle) was created by John Ousterhout in 1988. The graphical toolkit Tk has been available in 1991.
This is an interpreted scripting language, easy to learn where each thing is a command and can be redefined. The syntax uses plenty of symbols as C but is not that of C. (In C each thing is an expression).

Features

Syntax

An instruction is the name of a command (not a keyword) followed by a list of words separated by a whitespace, the arguments.
Statements end with the end of the line. They may be separated by a semi-colon on a same line.
Square brackets replace an argument by a command. These are so a substitution  symbols.
The = sign is never used, the "set" command assigns a value to a variable:

set varname value

The { } serve for grouping, without subsitution.
# introduces a comment.

Control structures

The if command use two groups { }, the first for the condition, the second for the actions.

if { x < 10 } 
{ 
 puts "x less than 10" 
}

The while command has the same syntax.

Procedures

The definition starts with the proc command, plus the name and two groups for the arguments and the statements.

proc procname { arguments }
{
 ...statements...
}

Why to use Tcl?

Sites

• Tcl/Tk
  Main site.
• Tutorial
  Getting started with Tcl.
• FAQ
• Dmoz
  The TCL directory on ODP.

Sample code

puts "Hello, world!" 

array mylist { d e m o } 
 
foreach i [ array mylist ]
{
  puts [ concat $i = $mylist($i) ]
} 

References

• John K. Ousterhout, Tcl and the Tk Toolkit, Addison-Wesley.
• History of Tcl.