is a predicate for applications which consist only of Tcl code (no C extensions or packages). PRO: * portable, will run on most or all platforms * easily edited even in deployed form CON: * may run slower, especially in number-crunching * may expose implementation details that the end user is not supposed to know In general, it is sensible to start coding an app in pure Tcl, and replace only those parts (if any) with C code that are just too slow. (But CPUs are picking up speed considerably faster than C coders ;-) ([RS]) ---- There are several subtleties and even polysemies to this term. Sometimes we say, "pure Tcl" in contrast to Tk; thus the 2.0 version of [sockspy] is useful for certain contexts because it can be run as "pure Tcl" without the requirement for a Tk interpreter.