(* Title: HOLCF/ex/Stream.thy
ID: $Id$
Author: Franz Regensburger, David von Oheimb
License: GPL (GNU GENERAL PUBLIC LICENSE)
General Stream domain.
TODO: should be integrated with HOLCF/Streams
*)
Stream = HOLCF + Nat_Infinity +
domain 'a stream = "&&" (ft::'a) (lazy rt::'a stream) (infixr 65)
consts
smap :: "('a -> 'b) -> 'a stream -> 'b stream"
sfilter :: "('a -> tr) -> 'a stream -> 'a stream"
slen :: "'a stream => inat" ("#_" [1000] 1000)
defs
smap_def "smap == fix\\<cdot>(\\<Lambda> h f s. case s of x && xs => f\\<cdot>x && h\\<cdot>f\\<cdot>xs)"
sfilter_def "sfilter == fix\\<cdot>(\\<Lambda> h p s. case s of x && xs =>
If p\\<cdot>x then x && h\\<cdot>p\\<cdot>xs else h\\<cdot>p\\<cdot>xs fi)"
slen_def "#s == if stream_finite s
then Fin (LEAST n. stream_take n\\<cdot>s = s) else \\<infinity>"
end