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(* Title: TFL/dcterm.ML


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ID: $Id$


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Author: Konrad Slind, Cambridge University Computer Laboratory


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Copyright 1997 University of Cambridge


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*)


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(*


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* Derived efficient cterm destructors.


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**)


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signature DCTERM =


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sig


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val dest_comb: cterm > cterm * cterm


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val dest_abs: string option > cterm > cterm * cterm


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val capply: cterm > cterm > cterm


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val cabs: cterm > cterm > cterm


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val mk_conj: cterm * cterm > cterm


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val mk_disj: cterm * cterm > cterm


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val mk_exists: cterm * cterm > cterm


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val dest_conj: cterm > cterm * cterm


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val dest_const: cterm > {Name: string, Ty: typ}


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val dest_disj: cterm > cterm * cterm


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val dest_eq: cterm > cterm * cterm


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val dest_exists: cterm > cterm * cterm


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val dest_forall: cterm > cterm * cterm


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val dest_imp: cterm > cterm * cterm


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val dest_let: cterm > cterm * cterm


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val dest_neg: cterm > cterm


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val dest_pair: cterm > cterm * cterm


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val dest_var: cterm > {Name:string, Ty:typ}


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val is_conj: cterm > bool


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val is_cons: cterm > bool


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val is_disj: cterm > bool


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val is_eq: cterm > bool


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val is_exists: cterm > bool


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val is_forall: cterm > bool


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val is_imp: cterm > bool


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val is_let: cterm > bool


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val is_neg: cterm > bool


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val is_pair: cterm > bool


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val list_mk_disj: cterm list > cterm


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val strip_abs: cterm > cterm list * cterm


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val strip_comb: cterm > cterm * cterm list


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val strip_disj: cterm > cterm list


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val strip_exists: cterm > cterm list * cterm


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val strip_forall: cterm > cterm list * cterm


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val strip_imp: cterm > cterm list * cterm


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val drop_prop: cterm > cterm


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val mk_prop: cterm > cterm


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end;


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structure Dcterm: DCTERM =


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struct


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structure U = Utils;


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fun ERR func mesg = U.ERR {module = "Dcterm", func = func, mesg = mesg};


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fun dest_comb t = Thm.dest_comb t


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handle CTERM msg => raise ERR "dest_comb" msg;


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fun dest_abs a t = Thm.dest_abs a t


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handle CTERM msg => raise ERR "dest_abs" msg;


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fun capply t u = Thm.capply t u


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handle CTERM msg => raise ERR "capply" msg;


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fun cabs a t = Thm.cabs a t


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handle CTERM msg => raise ERR "cabs" msg;


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(*

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* SOME simple constructor functions.

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**)


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val mk_hol_const = Thm.cterm_of (Theory.sign_of HOL.thy) o Const;


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fun mk_exists (r as (Bvar, Body)) =


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let val ty = #T(rep_cterm Bvar)


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val c = mk_hol_const("Ex", (ty > HOLogic.boolT) > HOLogic.boolT)


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in capply c (uncurry cabs r) end;


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local val c = mk_hol_const("op &", HOLogic.boolT > HOLogic.boolT > HOLogic.boolT)


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in fun mk_conj(conj1,conj2) = capply (capply c conj1) conj2


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end;


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local val c = mk_hol_const("op ", HOLogic.boolT > HOLogic.boolT > HOLogic.boolT)


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in fun mk_disj(disj1,disj2) = capply (capply c disj1) disj2


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end;


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(*


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* The primitives.


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**)


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fun dest_const ctm =


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(case #t(rep_cterm ctm)


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of Const(s,ty) => {Name = s, Ty = ty}


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 _ => raise ERR "dest_const" "not a constant");


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fun dest_var ctm =


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(case #t(rep_cterm ctm)


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of Var((s,i),ty) => {Name=s, Ty=ty}


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 Free(s,ty) => {Name=s, Ty=ty}


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 _ => raise ERR "dest_var" "not a variable");


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(*


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* Derived destructor operations.


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**)


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fun dest_monop expected tm =


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let


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fun err () = raise ERR "dest_monop" ("Not a(n) " ^ quote expected);


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val (c, N) = dest_comb tm handle U.ERR _ => err ();


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val name = #Name (dest_const c handle U.ERR _ => err ());


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in if name = expected then N else err () end;


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fun dest_binop expected tm =


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let


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fun err () = raise ERR "dest_binop" ("Not a(n) " ^ quote expected);


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val (M, N) = dest_comb tm handle U.ERR _ => err ()


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in (dest_monop expected M, N) handle U.ERR _ => err () end;


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fun dest_binder expected tm =

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dest_abs NONE (dest_monop expected tm)

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handle U.ERR _ => raise ERR "dest_binder" ("Not a(n) " ^ quote expected);


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val dest_neg = dest_monop "not"


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val dest_pair = dest_binop "Pair";


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val dest_eq = dest_binop "op ="


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val dest_imp = dest_binop "op >"


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val dest_conj = dest_binop "op &"


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val dest_disj = dest_binop "op "


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val dest_cons = dest_binop "Cons"


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val dest_let = Library.swap o dest_binop "Let";

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val dest_select = dest_binder "Hilbert_Choice.Eps"

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val dest_exists = dest_binder "Ex"


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val dest_forall = dest_binder "All"


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(* Query routines *)


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val is_eq = can dest_eq


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val is_imp = can dest_imp


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val is_select = can dest_select


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val is_forall = can dest_forall


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val is_exists = can dest_exists


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val is_neg = can dest_neg


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val is_conj = can dest_conj


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val is_disj = can dest_disj


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val is_pair = can dest_pair


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val is_let = can dest_let


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val is_cons = can dest_cons


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(*


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* Iterated creation.


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**)


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val list_mk_disj = U.end_itlist (fn d1 => fn tm => mk_disj (d1, tm));


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(*


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* Iterated destruction. (To the "right" in a term.)


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**)


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fun strip break tm =


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let fun dest (p as (ctm,accum)) =


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let val (M,N) = break ctm


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in dest (N, M::accum)


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end handle U.ERR _ => p


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in dest (tm,[])


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end;


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fun rev2swap (x,l) = (rev l, x);


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val strip_comb = strip (Library.swap o dest_comb) (* Goes to the "left" *)


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val strip_imp = rev2swap o strip dest_imp

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val strip_abs = rev2swap o strip (dest_abs NONE)

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val strip_forall = rev2swap o strip dest_forall


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val strip_exists = rev2swap o strip dest_exists


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val strip_disj = rev o (op::) o strip dest_disj


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(*


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* Going into and out of prop


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**)


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fun mk_prop ctm =


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let val {t, sign, ...} = Thm.rep_cterm ctm in


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if can HOLogic.dest_Trueprop t then ctm


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else Thm.cterm_of sign (HOLogic.mk_Trueprop t)


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end


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handle TYPE (msg, _, _) => raise ERR "mk_prop" msg


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 TERM (msg, _) => raise ERR "mk_prop" msg;


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fun drop_prop ctm = dest_monop "Trueprop" ctm handle U.ERR _ => ctm;


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end;
