Jacl
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Jacl is an implementation of Tcl.
Other implementations of Tcl.
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).
Consider using JTcl instead, which supports a larger fraction of the Tcl language and has more active developers working on it.