1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/Pure/primitive_defs.ML	Tue Aug 14 13:20:17 2007 +0200
     1.3 @@ -0,0 +1,88 @@
     1.4 +(*  Title:      Pure/primitive_defs.ML
     1.5 +    ID:         $Id$
     1.6 +    Author:     Makarius
     1.7 +
     1.8 +Primitive definition forms.
     1.9 +*)
    1.10 +
    1.11 +signature PRIMITIVE_DEFS =
    1.12 +sig
    1.13 +  val dest_def: Pretty.pp -> (term -> bool) -> (string -> bool) -> (string -> bool) ->
    1.14 +    term -> (term * term) * term
    1.15 +  val abs_def: term -> term * term
    1.16 +  val mk_defpair: term * term -> string * term
    1.17 +end;
    1.18 +
    1.19 +structure PrimitiveDefs: PRIMITIVE_DEFS =
    1.20 +struct
    1.21 +
    1.22 +fun term_kind (Const _) = "existing constant "
    1.23 +  | term_kind (Free _) = "free variable "
    1.24 +  | term_kind (Bound _) = "bound variable "
    1.25 +  | term_kind _ = "";
    1.26 +
    1.27 +(*c x == t[x] to !!x. c x == t[x]*)
    1.28 +fun dest_def pp check_head is_fixed is_fixedT eq =
    1.29 +  let
    1.30 +    fun err msg = raise TERM (msg, [eq]);
    1.31 +    val eq_vars = Term.strip_all_vars eq;
    1.32 +    val eq_body = Term.strip_all_body eq;
    1.33 +
    1.34 +    val display_terms =
    1.35 +      commas_quote o map (Pretty.string_of_term pp o Syntax.bound_vars eq_vars);
    1.36 +    val display_types = commas_quote o map (Pretty.string_of_typ pp);
    1.37 +
    1.38 +    val (raw_lhs, rhs) = Logic.dest_equals eq_body handle TERM _ => err "Not a meta-equality (==)";
    1.39 +    val lhs = Envir.beta_eta_contract raw_lhs;
    1.40 +    val (head, args) = Term.strip_comb lhs;
    1.41 +    val head_tfrees = Term.add_tfrees head [];
    1.42 +
    1.43 +    fun check_arg (Bound _) = true
    1.44 +      | check_arg (Free (x, _)) = not (is_fixed x)
    1.45 +      | check_arg (Const ("TYPE", Type ("itself", [TFree _]))) = true
    1.46 +      | check_arg _ = false;
    1.47 +    fun close_arg (Bound _) t = t
    1.48 +      | close_arg x t = Term.all (Term.fastype_of x) $ lambda x t;
    1.49 +
    1.50 +    val lhs_bads = filter_out check_arg args;
    1.51 +    val lhs_dups = duplicates (op aconv) args;
    1.52 +    val rhs_extras = Term.fold_aterms (fn v as Free (x, _) =>
    1.53 +      if is_fixed x orelse member (op aconv) args v then I
    1.54 +      else insert (op aconv) v | _ => I) rhs [];
    1.55 +    val rhs_extrasT = Term.fold_aterms (Term.fold_types (fn v as TFree (a, S) =>
    1.56 +      if is_fixedT a orelse member (op =) head_tfrees (a, S) then I
    1.57 +      else insert (op =) v | _ => I)) rhs [];
    1.58 +  in
    1.59 +    if not (check_head head) then
    1.60 +      err ("Bad head of lhs: " ^ term_kind head ^ display_terms [head])
    1.61 +    else if not (null lhs_bads) then
    1.62 +      err ("Bad arguments on lhs: " ^ display_terms lhs_bads)
    1.63 +    else if not (null lhs_dups) then
    1.64 +      err ("Duplicate arguments on lhs: " ^ display_terms lhs_dups)
    1.65 +    else if not (null rhs_extras) then
    1.66 +      err ("Extra variables on rhs: " ^ display_terms rhs_extras)
    1.67 +    else if not (null rhs_extrasT) then
    1.68 +      err ("Extra type variables on rhs: " ^ display_types rhs_extrasT)
    1.69 +    else if exists_subterm (fn t => t aconv head) rhs then
    1.70 +      err "Entity to be defined occurs on rhs"
    1.71 +    else
    1.72 +      ((lhs, rhs), fold_rev close_arg args (Term.list_all (eq_vars, (Logic.mk_equals (lhs, rhs)))))
    1.73 +  end;
    1.74 +
    1.75 +(*!!x. c x == t[x] to c == %x. t[x]*)
    1.76 +fun abs_def eq =
    1.77 +  let
    1.78 +    val body = Term.strip_all_body eq;
    1.79 +    val vars = map Free (Term.rename_wrt_term body (Term.strip_all_vars eq));
    1.80 +    val (lhs, rhs) = Logic.dest_equals (Term.subst_bounds (vars, body));
    1.81 +    val (lhs', args) = Term.strip_comb lhs;
    1.82 +    val rhs' = Term.list_abs_free (map Term.dest_Free args, rhs);
    1.83 +  in (lhs', rhs') end;
    1.84 +
    1.85 +fun mk_defpair (lhs, rhs) =
    1.86 +  (case Term.head_of lhs of
    1.87 +    Const (name, _) =>
    1.88 +      (NameSpace.base name ^ "_def", Logic.mk_equals (lhs, rhs))
    1.89 +  | _ => raise TERM ("Malformed definition: head of lhs not a constant", [lhs, rhs]));
    1.90 +
    1.91 +end;