jettison A and F as they're special cases of As and Fs
use auxiliary constructors instead of outside functions for convenience overloads; drawback: have to use `new` sometimes
Revert "use auxiliary constructors instead of outside functions for convenience overloads; drawback: have to use `new` sometimes"

This reverts commit 60b843e16187203097df4acbf67d2ad154cf2e5c.
renaming: Fs and As are weird names