The leaf elements are often coupled by a protocol, even if it's as simple as "call this API to return a result". Domain language is derived from seeing that a c

The leaf elements are often coupled by a protocol, even if it's as simple as "call this API to return a result". Domain language is derived from seeing that a certain conventional protocol is used over and over. So to me, protocol is the focus of modularity, because it lets you talk within the domain. However, protocol isn't addressed by generalizing it: that just means you have added a container for the meaningful part of the content. Something that comes up when working in a point-free style, as in Forth or APL, is that protocol is shoved in your face immediately because the sequence of arguments now matters, and that has downsides(stack underflow errors?) but also upsides (conciseness, ease of factoring). When I reach for that, it tends to mean that I intend to find a tighter specification for the domain.