- Critcl and so on
- compiled-in extensions
- "impedance-matching" loaders
- Incr TCL has Itcl_RegisterC function to register C functions as @function symbols in Itcl class members
For those broad-minded enough to replace "function" by process, TV recommends IPC:TV Don't forget that a possibly completely platform independent method is to pass messages over a socket to a C-code based process. Example: . Long ago I've made some automation scripts to generate the frame for this sort of method which is quite possible in tcl.