Hacker News Reader

Does OCaml do any sort of structural sharing behind the scenes? This is always the thing that bothers me about the functional JavaScript movement, since mutable state everywhere makes such sharing infeasible, meaning that I have to worry a lot more about space complexity when I'm doing something like a map over a collection. How does OCaml fare in that regard?

View on HN

Sharing is both common and expected, as it arises naturally as a result of writing functions over variants. The language also provides an identity test (==) by which sharing can be observed, so it can't be said to be "behind the scenes".

Several of the data structures in the stdlib make good use of sharing to reduce the cost of operations - Set.union is a particularly good example. map, however, is not the sort of operation that leads to sharing.

Reply on news.ycombinator.com