val typecheck                     : Types.t_exp -> (Types.ftype,  [> Types.typechecking_error]) result

val typecheck_polymorphic         : Types.t_exp -> (Types.type_f, [> Types.polytypechecking_error]) result

val typecheck_polymorphic_unbound : Types.t_exp -> (Types.type_f, [> Types.polytypechecking_error]) result