On Aug 22, 2014, at 1:45 PM, Rafael Fourquet <fourquet.raf...@gmail.com> wrote: > > In short, be lazy when it gives opportunity for loop fusion, and saves > allocations.
There's a complicated limit to when you want to fuse loops – at some point multiple iterations becomes better than fused loops and it all depends on how much and what kind of work you're doing. In general doing things lazily does not cut down on allocation since you have to allocate the representation of the operations that you're deferring and close over any values that they depend on. This particular example only works out so well because the iterable is so simple that the compiler can eliminate the laziness and do the eager loop fused version for you. This will not generally be the case. You're welcome to experiment (and Julia's type system makes it pretty easy to do so), but I think that you'll quickly find that more laziness is not a panacea for performance problems.
