Source : Free On-Line Dictionary of Computing

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)