1. Faster LEX.
2. A real-time language for dynamic environments.
["FLEX: Towards Flexible Real-Time Programs", K. Lin et al, Computer Langs 16(1):65-79, Jan 1991].
3. An early object-oriented language developed for the FLEX machine by Alan Kay in about 1967. The FLEX language was a simplification of Simula and a predecessor of Smalltalk.
A system developed by Ian Currie (Iain?) at the (then) Royal Signals and Radar Establishment at Malvern in the late 1970s. The hardware was custom and microprogrammable, with an operating system, (modular) compiler, editor, garbage collector and filing system all written in Algol-68. Flex was also re-implemented on the Perq(?).
[I. F. Currie and others, "Flex Firmware", Technical Report, RSRE, Number 81009, 1981].
[I. F. Currie, "In Praise of Procedures", RSRE, 1982].