Hi!
Is there a way to have locally bound recursive lazy sequences in
Clojure? I'd like to define a function that uses a lazy seq as an
interim result, so i wouldn't want to use a top-level def.
I'll try to give a short example. You can define the sequence of
fibonacci numbers lazily-recursively like this:
(def fibs (lazy-cat '(0 1) (map + fibs (drop 1 fibs))))
Now suppose you want to define a function which returns the nth
fibonacci number, but you down want "fibs" around globally. My guess
was:
(defn fib [n]
(let [fibs2 (lazy-cat '(0 1) (map + fibs2 (drop 1 fibs2)))]
(nth fibs2 n)))
But this yields "Unable to resolve symbol: fibs2 in this context", so
let doesn't allow being self-referential the way def does. I don't
quite understand why the second arg to lazy-cat is being evaluated in
the first place. Shouldn't evaluation be delayed until needed?
Does anyone know how to get around this?
Thanks a lot!
Kind regards,
achim
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