14-Sep-2017: I'm a newcomer to TCL examining it as a possible platform for internal engineering tools.
The jury is still out. More later.
11-Oct-2017: The jury is in and despite first appearances, TCL has a large collection of tools, packages, information, and resources that makes it a great fit for engineering tools for industrial control (and probably many other fields as well).
APN Glad to have you aboard! I think Tcl's ease of integration with C also plays a part in it being used in commercial CAD tools, HyperMesh etc.