A♯ (pronounced: A sharp) is an object-oriented functional programming language distributed as a separable component of Version 2 of the Axiom computer algebra system.
A# types and functions are first-class values and can be used freely together with an extensive library of data structures and other mathematical abstractions.
A key design guideline for A# was suitability of compiling to portable and efficient machine code.
It is distributed as free and open-source software under a BSD-like license.
[1] Development of A# has now changed to the programming language Aldor.