**tcl::mathop** is a Tcl 8.5 namespace that contains commands equivalent to the expr operators. These commands are all bytecode compiled. Note that changing or adding to these commands does *not* change the expr operators themselves.

See Math Operators as Commands and tcl::mathfunc

A simple example, because I couldn't immediately work out the incantation to make mathops visible. Note that functions and operators come from different namespaces:

namespace import ::tcl::mathop::* namespace import ::tcl::mathfunc::* puts [* [sqrt 49] [+ 1 2 3]]

Alternatively:

namespace path {tcl::mathop tcl::mathfunc} puts [* [sqrt 49] [+ 1 2 3]]

There are better examples of the use of mathop scattered through the wiki; somebody should add links to some of the ones less obvious to non-lispers!