I'd actually prefer to do things a little differently with all the buffering functions. In particular, I think that buffering n xs should fill the buffer with n elements immediately, rather than doing nothing until the result is forced to WHNF. But consistency among these functions seems pretty important.

@simonmar, for the sake of consistency with the rest of the module, I don't think the poorly named buffering function should actually be added. Rather, I think it should replace evalBuffer. We could use rewrite rules internally to optimize evalBuffer (rseq `dot` strat), but I'm not sure that's really worth the trouble. On the other hand, that would be a breaking change.

@simonmar, I've made the changes much more conservative, which I'm hoping will make it easier to merge. In particular, I have ideas about reworking the way we deal with RULES and inlining, but they don't really belong here. I can likely borrow an 8-core machine to run the benchmarks; I'll have to try that later in the week. I continue to wonder what you think about the proposed semantic changes:

1. Make evalBuffer only evaluate as far as the passed strategy says, rather than to WHNF. (This is not incorporated into the PR).
2. Make parBuffer spark computations that only evaluate as far as the passed strategy says. (This is incorporated into the PR).

Hi @treeowl - I'm inclined to be very conservative with merging further changes to this package, given that we've all become confused at one time or another about how things are supposed to work. So let me propose that before merging any further PRs, especially unforced ones, we should

• make the test suite work with Travis
• do some benchmarking for every PR to ensure that it doesn't regress parallel performance (I'm quite concerned that we haven't done any benchmarking so far, and the whole reason this package exists is for performance)

I think we should replace evalBuffer by buffering (but keep the type), since the current behaviour (evaluating every element at least to WHNF, regardless of the strategy) is quite unexpected.

@treeowl would you mind updating the PR? Otherwise, I can take over.

I can try to page it back in; it's been a while since I wrote this.