Pop-11
A programming language created by Robin Popplestone in 1975, originally for the PDP-11. Pop-11 is stack-oriented, extensible, and efficient like FORTH. It is also functional, dynamically typed, interactive, with garbage collection like LISP, and the syntax is block structured like Pascal.
["Programming in POP-11", J. Laventhol <jcl@deshaw.com>, Blackwell 1987].
AlphaPop is an implementation for the Macintosh from Computable Functions Inc. PopTalk and POPLOG from the University of Sussex are available for VAX/VMS and most workstations.