A tree structure with two kinds of holes.
A tree structure with two kinds of holes. See BinaryOps.eval.
A tree structure with three kinds of holes.
A tree structure with three kinds of holes. See TernaryOps.eval.
A tree structure with one kind of hole.
A tree structure with one kind of hole. See UnaryOps.eval.
"Generic" types for building partially-constructed trees in some "functorized" type.