src/ZF/ex/Term.thy
 author clasohm Tue Feb 06 12:27:17 1996 +0100 (1996-02-06) changeset 1478 2b8c2a7547ab parent 1401 0c439768f45c child 3840 e0baea4d485a permissions -rw-r--r--
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1 (*  Title:      ZF/ex/Term.thy
2     ID:         \$Id\$
3     Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
4     Copyright   1994  University of Cambridge
6 Terms over an alphabet.
7 Illustrates the list functor (essentially the same type as in Trees & Forests)
8 *)
10 Term = List +
11 consts
12   term_rec  :: [i, [i,i,i]=>i] => i
13   term_map  :: [i=>i, i] => i
14   term_size :: i=>i
15   reflect   :: i=>i
16   preorder  :: i=>i
18   term      :: i=>i
20 datatype
21   "term(A)" = Apply ("a: A", "l: list(term(A))")
22   monos       "[list_mono]"
24   type_elims  "[make_elim (list_univ RS subsetD)]"
25 (*Or could have
26     type_intrs  "[list_univ RS subsetD]"
27 *)
29 defs
30   term_rec_def
31    "term_rec(t,d) ==
32    Vrec(t, %t g. term_case(%x zs. d(x, zs, map(%z.g`z, zs)), t))"
34   term_map_def  "term_map(f,t) == term_rec(t, %x zs rs. Apply(f(x), rs))"
36   term_size_def "term_size(t) == term_rec(t, %x zs rs. succ(list_add(rs)))"
38   reflect_def   "reflect(t) == term_rec(t, %x zs rs. Apply(x, rev(rs)))"
40   preorder_def  "preorder(t) == term_rec(t, %x zs rs. Cons(x, flat(rs)))"
42 end