theory Scratch
  imports Main
begin

(* A contrieved example *)
definition "enumhd = hd Enum.enum"
definition "code = ([enumhd,enumhd,enumhd,enumhd,enumhd,enumhd] :: (bool*bool*bool*bool*bool) list)"

(* To inspect the code *)
export_code code in SML file_prefix "enumhd"
(* Result: code that contains many copies of

    enumhd
     (Enum.enum_prod Enum.enum_bool
       (Enum.enum_prod Enum.enum_bool
         (Enum.enum_prod Enum.enum_bool
           (Enum.enum_prod Enum.enum_bool Enum.enum_bool))))

   The type classes are contructed over and over at runtime and slow down compiling.
*)

(* Running the code *)
value code

(* This should give us potential speedups *)
code_reflect enumhd functions enumhd
(* But it does not work because code_reflect produces ML function with different type class arguments *)
value code