List of elements of a structure, from left to right. If the entire
list is intended to be reduced via a fold, just fold the structure
directly bypassing the list.
Given a Lift n constraint in a signature carried by
m, sendM promotes arbitrary actions of type n
a to m a. It is spiritually similar to lift
from the MonadTrans typeclass.
Convert a prim monad to another prim monad.
The net effect is that it coerce the state repr to another, so the
runtime representation should be the same, otherwise hilary ensues.