My mistake; unchecked operations work just fine if their arguments
(including constants) are given type hints. What happens if unchecked-
add/sub/... is given an argument of unknown type, though? It still
seems to work, though slowly.
On Dec 14, 12:35 pm, Michel Salim <michel.syl...@gmail.com> wrote:
> This follows from the recent micro-benchmarking discussion, though as
> it concerns a potential bug, I'm starting a new thread.
>
> With this (very inefficient) implementation of fib,
>
> (defn fib [n]
> (if (<= n 1)
> 1
> (+ (fib (dec n)) (fib (- n 2)))))
>
> computing (fib 40) takes, give or take, 12 seconds on a Core 2 (2
> GHz).
>
> Substituting unchecked-{add,dec,subtract} for +, dec and -, I've not
> been able to complete (fib 40). For (fib 20), the original takes 63 ms
> whereas the unchecked version takes 2215 ms.
>
> Que pasa?
>
> --
> Michel
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