type literal =
    | Integer of int
    | Float of float

type ('a, 'b) expr =
    | Base of 'a
    | Paren of 'b
    | Neg of 'b
    | Mult of 'b * 'b
    ...
    | Lit of literal

type types = Tint | Tfloat

type ('a, 'b) top =
    (* def type name exprs *)
    | Func of types * string * ('a, 'b) expr


(* This definition is magical.
 * What it allows us to do is pair any amount of information with our AST,
 * without too much fiddling. Such as type data, or w/e else we might want.
 *)
type ('a, 'b) ast = Ast of 'a * ('b, ('a, 'b) ast) top