sig
type prim = Expr.e_val list -> Expr.e_val
type desc = Types.typ_scheme * Builtins.prim
type env = (string * Builtins.desc) list
val env : Builtins.env
exception Unbound_id of string
val lookup : string -> Builtins.desc
val lookup_typ : string -> Types.typ_scheme
val lookup_val : string -> Builtins.prim
end