diff -r b93cc55cb7ab -r df6b3bd14dcb ex/SList.thy --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ex/SList.thy Fri Dec 02 16:09:49 1994 +0100 @@ -0,0 +1,120 @@ +(* Title: HOL/ex/SList.thy + ID: $Id$ + Author: Lawrence C Paulson, Cambridge University Computer Laboratory + Copyright 1993 University of Cambridge + +Definition of type 'a list (strict lists) by a least fixed point + +We use list(A) == lfp(%Z. {NUMB(0)} <+> A <*> Z) +and not list == lfp(%Z. {NUMB(0)} <+> range(Leaf) <*> Z) +so that list can serve as a "functor" for defining other recursive types +*) + +SList = Sexp + + +types + 'a list + +arities + list :: (term) term + + +consts + + list :: "'a item set => 'a item set" + Rep_list :: "'a list => 'a item" + Abs_list :: "'a item => 'a list" + NIL :: "'a item" + CONS :: "['a item, 'a item] => 'a item" + Nil :: "'a list" + "#" :: "['a, 'a list] => 'a list" (infixr 65) + List_case :: "['b, ['a item, 'a item]=>'b, 'a item] => 'b" + List_rec :: "['a item, 'b, ['a item, 'a item, 'b]=>'b] => 'b" + list_case :: "['b, ['a, 'a list]=>'b, 'a list] => 'b" + list_rec :: "['a list, 'b, ['a, 'a list, 'b]=>'b] => 'b" + Rep_map :: "('b => 'a item) => ('b list => 'a item)" + Abs_map :: "('a item => 'b) => 'a item => 'b list" + null :: "'a list => bool" + hd :: "'a list => 'a" + tl,ttl :: "'a list => 'a list" + mem :: "['a, 'a list] => bool" (infixl 55) + list_all :: "('a => bool) => ('a list => bool)" + map :: "('a=>'b) => ('a list => 'b list)" + "@" :: "['a list, 'a list] => 'a list" (infixr 65) + filter :: "['a => bool, 'a list] => 'a list" + + (* list Enumeration *) + + "[]" :: "'a list" ("[]") + "@list" :: "args => 'a list" ("[(_)]") + + (* Special syntax for list_all and filter *) + "@Alls" :: "[idt, 'a list, bool] => bool" ("(2Alls _:_./ _)" 10) + "@filter" :: "[idt, 'a list, bool] => 'a list" ("(1[_:_ ./ _])") + +translations + "[x, xs]" == "x#[xs]" + "[x]" == "x#[]" + "[]" == "Nil" + + "case xs of Nil => a | y#ys => b" == "list_case(a, %y ys.b, xs)" + + "[x:xs . P]" == "filter(%x.P,xs)" + "Alls x:xs.P" == "list_all(%x.P,xs)" + +defs + (* Defining the Concrete Constructors *) + NIL_def "NIL == In0(Numb(0))" + CONS_def "CONS(M, N) == In1(M $ N)" + +inductive "list(A)" + intrs + NIL_I "NIL: list(A)" + CONS_I "[| a: A; M: list(A) |] ==> CONS(a,M) : list(A)" + +rules + (* Faking a Type Definition ... *) + Rep_list "Rep_list(xs): list(range(Leaf))" + Rep_list_inverse "Abs_list(Rep_list(xs)) = xs" + Abs_list_inverse "M: list(range(Leaf)) ==> Rep_list(Abs_list(M)) = M" + + +defs + (* Defining the Abstract Constructors *) + Nil_def "Nil == Abs_list(NIL)" + Cons_def "x#xs == Abs_list(CONS(Leaf(x), Rep_list(xs)))" + + List_case_def "List_case(c, d) == Case(%x.c, Split(d))" + + (* list Recursion -- the trancl is Essential; see list.ML *) + + List_rec_def + "List_rec(M, c, d) == wfrec(trancl(pred_sexp), M, \ +\ List_case(%g.c, %x y g. d(x, y, g(y))))" + + list_rec_def + "list_rec(l, c, d) == \ +\ List_rec(Rep_list(l), c, %x y r. d(Inv(Leaf, x), Abs_list(y), r))" + + (* Generalized Map Functionals *) + + Rep_map_def "Rep_map(f, xs) == list_rec(xs, NIL, %x l r. CONS(f(x), r))" + Abs_map_def "Abs_map(g, M) == List_rec(M, Nil, %N L r. g(N)#r)" + + null_def "null(xs) == list_rec(xs, True, %x xs r.False)" + hd_def "hd(xs) == list_rec(xs, @x.True, %x xs r.x)" + tl_def "tl(xs) == list_rec(xs, @xs.True, %x xs r.xs)" + (* a total version of tl: *) + ttl_def "ttl(xs) == list_rec(xs, [], %x xs r.xs)" + + mem_def "x mem xs == \ +\ list_rec(xs, False, %y ys r. if(y=x, True, r))" + list_all_def "list_all(P, xs) == list_rec(xs, True, %x l r. P(x) & r)" + map_def "map(f, xs) == list_rec(xs, [], %x l r. f(x)#r)" + append_def "xs@ys == list_rec(xs, ys, %x l r. x#r)" + filter_def "filter(P,xs) == \ +\ list_rec(xs, [], %x xs r. if(P(x), x#r, r))" + + list_case_def "list_case(a, f, xs) == list_rec(xs, a, %x xs r.f(x, xs))" + +end