The Free On-line Dictionary of Computing (30 December 2018):

LeFun

   Logic, Equations and Functions.  An integration of logic
   programming and functional programming by H. Ait-Kaci et al
   of MCC, Austin TX.

   ["LeFun: Logic, Equations and Functions", H. Ait-Kaci et al,
   Proc 1987 Symp on Logic Programming, San Francisco].

   (1994-10-21)