Early sightings

• Lisp "property lists" (1960ish)

• SNOBOL "tables" (1965ish)

• awk "associative arrays" (Unix, 1977)

• This is the earliest implementation that I know used hash tables

• REXX "stem variables" (OS/370, 1979)

• These were not actually very good

• Perl / Python (1987–1990ish)