On 14 Oct 2010, at 21:52, clwham...@gmail.com wrote:
I need a function that produces the 'next' value from a lazy-seq --
something like a Python generator. I imagine it would have to be some
sort of closure like:
(def next-sine
(let [sines (atom (cycle (map sin (range 0 6.28 0.01))))]
#(swap! sines rest)))
Is there a more idomatic way of doing this? I don't see a lot of use
of closures in clojure...
Closures are common in Clojure, but mostly they capture values rather
than storage locations.
Could you tell us why you "need" a function that relies on mutable
state? Clojure has lots of functions to make, transform, and use
sequences in a functional style, and those are usually preferred.
If your need comes from the wish to do stream processing without
passing the stream around explicitly among lots of functions, consider
using monads to abstract away the stream argument:
http://github.com/clojure/clojure-contrib/blob/master/modules/stream-utils/src/main/clojure/clojure/contrib/stream_utils.clj
Konrad.
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