FL (short for "Function Level") is a programming language created at the IBM Almaden Research Center by John Backus, John Williams, and Edward Wimmers in the 1980s and documented in a report from 1989.
[1] FL was designed as a successor of Backus's earlier FP language, providing specific support for what Backus termed function-level programming.
FL is a dynamically typed strict functional programming language with throw and catch exception semantics much like in ML.
For doing optimization, there exists a type-system which is an extension of Hindley–Milner type inference.
PLaSM is a "geometry-oriented extension of a subset of the FL language"[2] first described in 1992.