--- a/src/ZF/ListFn.thy Thu Sep 30 10:10:21 1993 +0100
+++ b/src/ZF/ListFn.thy Thu Sep 30 10:26:38 1993 +0100
@@ -18,6 +18,8 @@
length,rev :: "i=>i"
flat :: "i=>i"
list_add :: "i=>i"
+ hd,tl :: "i=>i"
+ drop :: "[i,i]=>i"
(* List Enumeration *)
"[]" :: "i" ("[]")
@@ -31,6 +33,11 @@
rules
+
+ hd_def "hd(l) == list_case(0, %x xs.x, l)"
+ tl_def "tl(l) == list_case(Nil, %x xs.xs, l)"
+ drop_def "drop(i,l) == rec(i, l, %j r. tl(r))"
+
list_rec_def
"list_rec(l,c,h) == Vrec(l, %l g.list_case(c, %x xs. h(x, xs, g`xs), l))"
@@ -40,5 +47,4 @@
rev_def "rev(l) == list_rec(l, Nil, %x xs r. r @ [x])"
flat_def "flat(ls) == list_rec(ls, Nil, %l ls r. l @ r)"
list_add_def "list_add(l) == list_rec(l, 0, %x xs r. x#+r)"
-
end