Vlisp

Vlisp refers to at least three distinct items.

These are, in no particular order:

A Lisp dialect with a fast interpreter and a portable virtual machine. It introduced the "chronology", a dynamic environment for implementing interrupts. This Vlisp led to Le Lisp.
A formally verified implementation of the Scheme programming language (Scheme is a dialect of Lisp).
The "Visual Lisp" implementation included in recent versions of AutoCAD.

References

["Contribution a la Definition Interpretive et a l'Implementation des Lambda-Langages", P. Greussay, These d'Etat, U Paris VI, Nov 1977].

["VLISP: A Verified Implementation of Scheme", J. Guttman, J. Ramsdell, M. Wand]