--------------

app2
^^^^^^

Basis Function Combinator

Like app1 with two items.
    ::

               ... y x [Q] . app2
        -----------------------------------
           ... [y ...] [Q] . infra first
               [x ...] [Q]   infra first



Gentzen diagram.


Definition
~~~~~~~~~~

if not basis.


Derivation
~~~~~~~~~~

if not basis.


Source
~~~~~~~~~~

if basis


Discussion
~~~~~~~~~~

Lorem ipsum.


Crosslinks
~~~~~~~~~~

Lorem ipsum.