Get the minimum element of a monomorphic container, using a supplied
element ordering function.
Safe version of minimumByEx, only works on monomorphic
containers wrapped in a NonNull.
Get the minimum element of a monomorphic container, using a supplied
element ordering function.
Note: this is a partial function. On an empty MonoFoldable, it
will throw an exception.
See minimumBy from Data.NonNull for a total version
of this function.