C programs of a particular type are known
as ''big wish'' programs.  They have this
name because of their similarity to the
[wish] program that is part of Tk.

Unless you are completely new to Tcl/Tk,
you are familiar with the program [tclsh].
With [tclsh] you can interactively enter
Tcl commands and see the results of their
evaluation.  Or you can name a script file
for [tclsh] to evaluate.  The Tcl interpreter
within [tclsh] starts out with all the
built-in command provided by the Tcl package.

The program [wish] is quite similar to [tclsh].
The primary difference is that the Tcl interpreter
within [wish] starts out with all the built-in
commands of both the Tcl and Tk packages.  The
commands of two packages combined in one interpreter
right from the startup of the program.

Other examples include:

   * ''expect'' - includes Tcl and [Expect] packages
   * ''expectTk'' - includes Tcl, Tk, and [Expect] packages
   * ''tcl'' - includes Tcl and [TclX] packages
   * ''itclsh'' - includes Tcl and [Itcl] packages

...and there are others.

As of 2003, these ''big wish'' programs are falling out
of favor.  Replacing them is the practice of making each
component package available as a [load]able extension, so
that each package can be pulled into the [tclsh] program
at runtime, as they are demanded by scripts evaluating
[[package require]] commands.  This is an example of
the extending solution winning out in the [embedding vs. extending]
contest.