[pfdietz]

Defining a number of related functions seems to be a pattern that comes up elsewhere. For example, consider functions that compute a hash value, canonicalize, and compute some notion of equality. It would be useful to associate all of these.

[moonchild]

Haskell calls these 'typeclasses'; cl calls them 'protocols'. Apl style is not to expose sophisticated user-level abstractions, so I think that there it is not inappropriate that the scope of associable objects (say, a monad, a dyad, an inverse, and an identity; perhaps a few others) be fixed by the language.