Spec - iterators about nimskull HOT 1 OPEN

Again this organization is great, it's pointing out the layers and dependencies really nicely.

In that vein, I believe for loops should be rearranged a bit:

• arrangement 1: be lumped in with iterators or a layer above.
• arrangement 2: have for loops easy mode which are only on ranges, slices and built in type things. Then the iterators democratized it by allowing user defines ones, so we revisit for loops (advanced mode) as they basically turn into a thin conceptual thing atop while + iterators.

The reasoning can be explained in a few ways, I'll list a few:

Way 1: if someone is making an alternative implementation (or adding a layer like CPS is now), a compiler author, then they can slowly conform to more advanced levels of the spec and even if it's not full conformance they can precisely know both the logical progression of how to implement things but users also know the level of support (eg: "nimskull level 7, everything but macros").

Way 2: if a user is learning from the spec then it is a nice gentle slope in terms of introducing and slowly revising and advancing the concepts. No information overload. Basically, oh yeah, I've seen for loops, nbd, next thing you know we have user defines iteration, after that for loop macros, then Galaxy brain CPS. 😁

Way 3: we can make tiny useful increments of progress without it feeling overwhelming. So pushing out the layers just means we can go up smaller hills at a time and I think it'll make it easier for others to contribute. My hypothesis is that they won't feel like they have to know each feature and every possible interaction all at once and need to be language experts.

Way 4: same as the above, but more from working on the implementation perspective, revising the implementation it gives progressive feedback and don't have to get the implementation right in one big bang.

The above isn't just for for loops of course, but I was able to explain it through them. Again, only thanks to bring able to see things so clearly sure to your efforts, so thank you. ❤️.

from nimskull.