signature QUOTIENT_DEF =

sig 

  val quotient_def: mixfix -> Attrib.binding -> term -> term ->

    local_theory -> (term * thm) * local_theory

  val quotdef_cmd: (Attrib.binding * string) * (mixfix * string) ->

    local_theory -> local_theory

end;

structure Quotient_Def: QUOTIENT_DEF =

struct

open Quotient_Info;

open Quotient_Term;

(* wrapper for define *)

fun define name mx attr rhs lthy =

let

  val ((rhs, (_ , thm)), lthy') =

     Local_Theory.define ((name, mx), (attr, rhs)) lthy

in

  ((rhs, thm), lthy')

end

(* interface and syntax setup *)

(* the ML-interface takes a 4-tuple consisting of *)

(*                                                *)

(* - the mixfix annotation                        *)

(* - name and attributes of the meta eq           *)

(* - the new constant including its type          *)

(* - the rhs of the definition                    *)

fun quotient_def mx attr lhs rhs lthy =

let

  val Free (lhs_str, lhs_ty) = lhs;

  val qconst_bname = Binding.name lhs_str;

  val absrep_trm = absrep_fun_chk absF lthy (fastype_of rhs, lhs_ty) $ rhs

  val prop = Logic.mk_equals (lhs, absrep_trm)

  val (_, prop') = LocalDefs.cert_def lthy prop

  val (_, newrhs) = Primitive_Defs.abs_def prop'

  val ((trm, thm), lthy') = define qconst_bname mx attr newrhs lthy

  fun qcinfo phi = qconsts_transfer phi {qconst = trm, rconst = rhs, def = thm}

  val lthy'' = Local_Theory.declaration true

                 (fn phi => qconsts_update_gen lhs_str (qcinfo phi)) lthy'

in

  ((trm, thm), lthy'')

end

fun quotdef_cmd ((attr, lhsstr), (mx, rhsstr)) lthy =

let

  val lhs = Syntax.read_term lthy lhsstr

  val rhs = Syntax.read_term lthy rhsstr

in

  quotient_def mx attr lhs rhs lthy |> snd

end

val _ = OuterKeyword.keyword "as";

val quotdef_parser =

  (SpecParse.opt_thm_name ":" --

     OuterParse.term) --

      (OuterParse.opt_mixfix' --| OuterParse.$$$ "as" --

         OuterParse.term)

val _ = OuterSyntax.local_theory "quotient_definition" 

	  "definition for constants over the quotient type"

             OuterKeyword.thy_decl (quotdef_parser >> quotdef_cmd)

end; (* structure *)