In APL, functions are
verbs,
and operators are
adverbs.
a program intensively using basic
operations on arrays is perfectly suitable
for superscalar processors in that it allows
a very high level of utilization of their
pipelined units.
Lastovetsky¹
From the earliest days of APL the adverbial aspect
of functions was achieved by embroidering the
function symbols with other symbols
Thomson & Polivka²
1.
A.L. Lastovetsky,
Parallel Computing on Heterogeneous Networks,
p. 22.