Now I see what you meant with those traits. Agree with:
Purely syntactic transformations are more intuitive and easier to debug when something goes wrong. I thought about requiring all inner function calls to have an explicit underscore: map(_ + 1) and map(isnothing(_)), but not map(isnothing). Then it would be possible to put the implicit ↑ argument right after these functions based on syntax alone, following the Julia argument order. But I decided that allowing map(isnothing) is more important than removing the need for an explicit ↑ in those rare cases when it should go to another argument (not the last).