Extending `for<'a>` construct

language design
12
  1. also seems like it might be difficult for the parser (and really should not be used IMO)
  2. yes definitely too subtle When comparing 3 and 4, look at how it looks with many bounds:
for<
    'a,
    'b,
    'c,
    'd,
    'e,
    'f,
    where
        'a: 'b,
        'c: 'f,
        'd: 'e,
> fn foo(...);
// vs
for<
    'a,
    'b,
    'c,
    'd,
    'e,
    'f,
> where<
    'a: 'b,
    'c: 'f,
    'd: 'e
> fn foo(...);

In option 3, i like that the > of the for is in front of fn, but the additonal indentation is not really nice (maybe indent the where by -1 and do not indent the bounds by +1). In option 4, i do not like the distance between the end of the for<> and fn. But overall I like option 4 more than putting the bounds even further away from the for. I think they should stay relatively close and be unambiguously connected.