> What would our languages look like if we made them shape polymorphic? If we moved in that direction it would be like baking the Composite Design Pattern deeply into language machinery. It could be very powerful.
In addition to APL and J, that would look a lot like SQL as well.
SQL uses explicit mapping with syntax that is more like list comprehension syntax in general purpose languages than function application syntax; it doesn't use implicit mapping.
(Though SQL often uses nullable values rather than a collection-like type for the use case where Scala uses Option types -- so the specific example used at the head of the article might look similar in SQL, but not because SQL is an example of the general approach the article is discussing.)
In addition to APL and J, that would look a lot like SQL as well.