What is the purpose of OCaml's Lazy.lazy_from_val?

Posted by Ricardo on Stack Overflow See other posts from Stack Overflow or by Ricardo
Published on 2012-03-18T17:39:54Z Indexed on 2012/03/18 17:56 UTC
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lazy-evaluation

The doc of Lazy.lazy_from_val states that this function is for special cases:

val lazy_from_val : 'a -> 'a t
  lazy_from_val v returns an already-forced suspension of v This is for special purposes only and should not be confused with lazy (v).

Which cases are they talking about?

If I create a pair of suspended computation from a value like:

let l1 = lazy 123
let l2 = Lazy.lazy_from_val 123

What is the difference between these two? Because Lazy.lazy_is_val l1 and Lazy.lazy_is_val l2 both return true saying that the value is already forced!

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