A general-arrays implementation of association lists
Mike Kent · ACM SIGAPL APL Quote Quad · 1993
Association lists are a data structure in which arbitrary values can be bound to equally arbitrary keys, and from which the bound values can subsequently be retrieved by specifying the appropriate key. Association lists are quite easy to implement in APLs which support general arrays; the implementation here is as two-column matrices with keys in the first column and the corresponding values in the second.