1 (**************************************************************************)
4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
13 (**************************************************************************)
15 include "ground/notation/functions/downdashedarrow_2.ma".
16 include "ground/lib/stream.ma".
18 (* HEAD AND TAIL FOR STREAMS ************************************************)
20 definition stream_hd (A:Type[0]): stream A → A.
24 definition stream_tl (A:Type[0]): stream A → stream A.
30 'DownDashedArrow A t = (stream_tl A t).
32 (* Basic constructions ******************************************************)
34 lemma stream_hd_cons (A) (a) (t):
35 a = stream_hd A (a⨮t).
38 lemma stream_tl_cons (A) (a) (t):
42 lemma stream_split_tl (A) (t):
43 stream_hd A t ⨮ ⇣t = t.