Emacs inferior-tcl mode

"M-x inferior-tcl" launches an embedded Tcl REPL in an Emacs buffer. "C-u M-x inferior-tcl" allows you to explicitly specify which binary to run as the Tcl interpreter, which is handy for picking Tcl versions, or picking between wish and tclsh. For example:

"C-u M-x inferior-tcl", then keying "tclsh8.6" would run tclsh8.6 on a system containing a Tcl 8.6 installation with a tclsh named tclsh8.6. "C-u M-x inferior-tcl" then keying "wish" would load a REPL into an Emacs buffer, and also load display a Tk window, like running "wish" typically does. The benefit is that you get full editing features of Emacs.