On Friday 12 February 2010 8:12:51 am Roman Leshchinskiy wrote:
That's actually a conscious decision. Since vectors support O(1) slicing, you can simply copy a slice of the source vector into a slice of the target vector.
Ah! I hadn't thought of that. That makes sense.
At the moment, it is (although it ought to be wrapped in a nicer interface). Something like memcpy doesn't work for Data.Vector.Unboxed because the ByteArrays aren't pinned. I don't really want to provide thawing until someone convinces me that it is actually useful.
Well, my use case is (of course) that I have lots of algorithms on mutable arrays, but they work just as well on immutable arrays by creating an intermediary. So I provided a combinator 'apply' that did something like: apply algo iv = new (safeThaw iv >>= \mv -> algo mv >> return mv) In uvector, the safeThaw part was copying iv into mv with a provided function. For the port, I used unstream . stream, which works fine assuming stream produces a correct size hint, I guess. That's the extent of what I have use for at the moment, though.
BTW, vector also supports array recycling so you could implement true in-place sorting for fused pipelines. Something like
map (+1) . sort . update xs
wouldn't allocate any temporary arrays in that case.
I'll look into it. -- Dan