Exactly, Partial application is a call side thing, which is pretty easy when you have curried functions, but also possible on non curried functions, by wrapping them into a clojure.
def add(a, b), do: a + b
def add2(), do: &add(2, &1)
def add(a), do: &(a + &1)
def add2(), do: add(2)
In both cases in add2/0 we use partial application to return a function, which would add 2 to its argument.
Just google explanations about how the scheduler assigns calculation times.
SImplified, each function you call will increase the reduction count of your process, and if it reaches a certain count, the process will be halted and the BEAM switches to the next one. Then other processes can run until your original is back on the table and can be run.
So, the more “needless” functions you call, the less CPU time you get.
I rarely use DI. And if I do, I usually consider it a part of the API. I do treat is quite often as call-site configuration ovverrides and handle them as part of the passed in config map/KW-list.
