Quiz: Remember the definition of mal de mer?
Arguably the current (2001) market-leading implementation of APL, from Dyalog Limited. Dyalog APL runs under Windows 95, Windows 98, Windows NT, and Windows 2000; and several popular UNIX systems including Linux.
Dyalog APL complies with ISO 8485 and has many features that make it good for complex GUI applications.
Dyalog APL was introduced in 1983 and is currently (2002) in active development.