ML, or Meta-Language, is a family of programming languages that are functional in nature. Functional programming is a programming style that is based on the evaluation of expressions rather than execution of commands. Functional programming is concerned with what needs to be done instead of how it is to be accomplished.

History

ML was first designed and implemented in the 1970s at the University of Edinburgh's Laboratory for Foundations of Computer Science. As the ML developed further in the 1980s, a common dialect and a base set of features was standardized. In 1990 the Standard ML (SML) was released. In 1997 the standard was revised as SML'97. SML is the most common implementation of ML.

In addition to SML, the ML family of languages includes Standard ML of New Jersey (SML/NJ), Extended ML (EML), Moscow ML, CAML, and others. ML is portable, and it has been implemented on a...