This week (likely most of the month) I am rebuilding a backup process which appears to currently rely on Syncthing and hasn’t been tested in years. Everybody got to put in their opinions, so I need to design something which has a single source of truth, also has 3-2-1 replica counts, takes snapshots of the production DBs without degrading them, and burns a monthly DVD on a workstation in the office. Once I’m done with that, I get to look at the office VPN’s performance problems.
Removed by mod
Reading between the lines, the documentation has the key:
Generic instances … correspond to
SemigroupandMonoidinstances defined by pointwise lifting.
In more words: each generic type can be broken up into a tuple-like row of components, and the generic type admits a monoid/semigroup whenever every component in the row admits a monoid/semigroup. In your handwritten Semigroup instance, the given code is agnostic as to the types of variables and functions; all that matters is that they already have Semigroup instances of their own.
Let me answer the other question: where’s the monoid in the generated Rep? Well, there isn’t one! The Rep merely has a struct-like product of component types. If a monoid exists for each component, then a monoid for the entire struct exists (and is built from the obvious pointwise lifting!) but otherwise there isn’t a monoid derived from the struct itself. This should be a notable contrast from generic instances for e.g. Functor, where every Rep has exactly zero or one Functor due to the algebra of the semiring of types (there is an underlying algebraic equation with at most one possible solution.)
You literally attach a license to every comment you post. The rules which make that license effective are the same rules which make Free Software and open-source licenses effective, too. Show some solidarity; you’re part of the community too, and you should feel comfortable making the same demands as the rest of us. When you say that “open source defenders” are distinct from “developers” you are contributing to a schism for the sake of aggrandizing employment and exploitation.