[jhuni]

I have heard of both this programming idioms: this and the original. In fact, both of these two programming idioms can be expressed in terms of in degree regular algebraic relations (e.g Common Lisp place forms). Indexes are places because you can retrieve the value at an index (nth coll i) and you can edit the value at the index (setf (nth coll i) val).

Slices of collections are themselves places, and they can be decomposed further into even finer places. In Common Lisp the subseq function describes such places: (setf (subseq coll start end) slice). Injective functions have an in degree regularity of one, which means that they are trivial place forms. As such, the original programming idiom can be described as a process that moves an object to a place, runs some functions, and then moves back to the starting place.