What languages used to write computer languages?
stan_rogers: It would have been difficult to have written APL in C originally, what with the lack of time machines and all (APL was created in '57 as an abstract notational concept and first implemented in '64 and released in '65; C was created in '72). The interpreter was probably written in S/360 assembler -- just a guess based on the fact that similar but simpler list/vector operations implemented 15 years later in the Lotus Notes macro (formula) language required write-only C wizardry on a truly heroic scope. Somehow I don't see anyone doing it in FORTRAN or COBOL without periodic psychiatric intervention.