Jacl is an implementation of Tcl written in Java rather than the (more common) C version shared by tclsh and wish. The current version does not implement quite the same version of the language, does not include any support for Tk, and instead includes a package for closer Java integration (allowing the use of the AWT, Swing, SWT, etc. for GUIs if desired).

Jacl is an implementation of Tcl. Other implementations of Tcl.

Consider using JTcl instead, which supports a larger fraction of the Tcl language and has more active developers working on it.