(*  Title:      HOL/IOA/Asig.thy

     ID:         $Id$

     Author:     Tobias Nipkow & Konrad Slind

     Copyright   1994  TU Muenchen

 *)

 header {* Action signatures *}

 theory Asig

 imports Main

 begin

 types

   'a signature = "('a set * 'a set * 'a set)"

 consts

   "actions" :: "'action signature => 'action set"

   "inputs" :: "'action signature => 'action set"

   "outputs" :: "'action signature => 'action set"

   "internals" :: "'action signature => 'action set"

   externals :: "'action signature => 'action set"

   is_asig       ::"'action signature => bool"

   mk_ext_asig   ::"'action signature => 'action signature"

 defs

 asig_inputs_def:    "inputs == fst"

 asig_outputs_def:   "outputs == (fst o snd)"

 asig_internals_def: "internals == (snd o snd)"

 actions_def:

    "actions(asig) == (inputs(asig) Un outputs(asig) Un internals(asig))"

 externals_def:

    "externals(asig) == (inputs(asig) Un outputs(asig))"

 is_asig_def:

   "is_asig(triple) ==

       ((inputs(triple) Int outputs(triple) = {})    &

        (outputs(triple) Int internals(triple) = {}) &

        (inputs(triple) Int internals(triple) = {}))"

 mk_ext_asig_def:

   "mk_ext_asig(triple) == (inputs(triple), outputs(triple), {})"

 ML {* use_legacy_bindings (the_context ()) *}

 end