What is the X in X-mas?
(REFAL) A language developed by V.F. Turchin (later at CUNY?) in Moscow in about 1972.
See also supercompilation.
[V.F. Turchin, "An algorithm of generalisation in the supercompiler", Workshop on partial evaluation and mixed computations, Oct 1987, Denmark, Eds. D. Bjorner, A.P. Ershov, N.D. Jones].
[V. Turchin, "Supercompiler System Based on the Language Refal", V. Turchin, SIGPLAN Notices 14(2):46-54 (Feb 1979)].