Source : Free On-Line Dictionary of Computing

ISWIM
     
        If You See What I Mean.  Landin 1966.  ISWIM is {purely
        functional}, a sugaring of {lambda-calculus}, and the ancestor
        of most modern {applicative} languages.  An ISWIM program is a
        single expression qualified by 'where' clauses (auxiliary
        definitions including equations among variables), conditional
        expressions and function definitions.  ISWIM was the first
        language to use {lazy evaluation} and introduced the {offside
        rule} for indentation.
     
        ["The Next 700 Programming Languages", P.J. Landin, CACM
        9(3):157-166 (Mar 1966)].