Tcl/Tk itself is not included in the SICStus distribution. It must be installed in order to use the interface. Many operating systems have build-in support for Tcl/Tk, either preinstalled or available via some software update utility. If a default version is not available, Tcl/Tk can be downloaded from the Tcl/Tk primary website:
http://tcl.sourceforge.net
A better alternative may be to use one of the free installers available from:
http://www.activestate.com
SICStus for Mac OS X uses the Tcl/Tk that comes with Mac OS X. Some
versions of Tcl/Tk provided by Apple have bugs that may cause SICStus
Prolog to crash when using library(tcltk). If this happens you
can try to update to a newer version of Tcl/Tk from
http://www.activestate.com.
The Tcl/Tk interface module included in
SICStus Prolog 4.3.1
(library(tcltk)) is verified to work with Tcl/Tk 8.4, and with
Tcl/Tk 8.5 for some platforms. See the SICStus download web page,
http://sicstus.sics.se/download4.html, for details.
Under UNIX, the installation program automatically detects the Tcl/Tk version (if the user does not specify it explicitly).
Please note: On Windows, you need to have the Tcl/Tk binaries accessible from your PATH environment variable, e.g. C:\Program Files\Tcl\bin.
The GUI version of SICStus, spwin, like all Windows non-console
applications, lacks the C standard streams
(stdin, stdout, stderr) and the Tcl command
puts and others that use these streams will therefore give
errors. The solution is to use sicstus instead of
spwin if the standard streams are required.