A+ is a Morgan Stanley array programming environment that includes
a rich set of functions and operators, handling of files as ordinary
arrays, a GUI with many widgets and automatic synchronization of
widgets and variables (using MStk in A+ Version 4), generalized
spreadsheet-like interactions, asynchronous execution of functions
that have been associated with variables and events, interprocess
communication, calls to user C subroutines, and many other features.
Execution is by a very efficient interpreter.