graydon/rust — comment on commit 8b57cb90e50b600824c967470483462aeb663e50
File: doc/tutorial/control.md line 127
By Lenny222:

Is it explained somwhere how "for in ..." is implemented?
I've assumed it uses an iterator, but i've found that "vec:iter" is implemented by means of "for in ...", so "for in ..." seems to be more fundamental.
How would you make it work for a custom type?