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

Information Processing Language

   (IPL) Said to be the first list-processing language, also the
   first language to support recursion.  Written by Allen
   Newell, J.C. Shaw and H. Simon at Carnegie ca. 1956.  It was
   very low level.

   Versions: IPL-I (never implemented), IPL-II (1957 for
   JOHNNIAC), IPL-III (existed briefly), IPL-IV, IPL-V (1958,
   for IBM 650, IBM 704, IBM 7090, many others.  Widely
   used), IPL-VI.

   [Sammet 1969, pp. 388-400].

   ["Information Processing Language-V Manual", A. Newell ed, P-H
   1965].

   (1994-11-04)