PAL (programming language)
Rpal is a functional programming language which is related to the ML programming language. RPAL is an acronym meaning "Right Reference - Pedagogic Algorithmic Language" and is a subset of PAL, a language invented by Evans and John Wozencraft in early 1970s at Massachusetts Institute of Technology for teaching programming language construction.
Overview
The Rpal language is used as a means of both teaching the construction of programming languages, as well as causing students to experience a paradigm shift as they change from the imperative model to the functional model. Programs in this language are made up of a single expression (because the language does not offer a sequencing operator). The other notable operator that the language is missing is an assign operator. The only way to change a variable is to create a new binding for it. This binding is permanent, and cannot be changed. The same name, however, may be rebound in a nested scope.