lviv is a functional stack-based programming language. Or maybe it's just a fancy programmable calculator.
lviv is written in Scheme. It's possible that it will work in a bunch of different Scheme environments, but I use Gambit-C Scheme v4.6.1 for development, so I don't guarantee that it'll work in any other scheme interpreter.
lviv is an experiment in hybrid functional-stack language design. The idea was to have a very regular syntax that was 100% compatible with postfix notation without requiring a modal interpreter (i.e., no ": ... ;" stuff like in FORTH; this means that everything, including lambda, define, if, let, et cetera, uses postfix notation) and with a minimal number of special forms. The original impetus came from a paper I read about how tail call optimization happens very naturally when the machine model is stack based. Naturally, lviv supports tail call optimization.
The name comes from the city of Lviv, where Jan Lukasiewicz was born. Lukasiewicz invented prefix or "Polish" notation to simplify the syntax of sentential logic; later, Burks, Warren, and Wright (and even later Bauer and Dijkstra) proposed postfix, or "reverse Polish" notation as a good fit for stack based machines.