In the Rust, constant traits can be used by unstable features. But who can tell me why some iterators is not constant (Like map)? ans why some constant iterators can't be create by their constructed function (Like once and empty)? When these constant iterator supports will be implemented?
People are gradually working on making more and more iterators (unstably) const. I believe that the current blocker on many of them is the fact that const closures are currently very buggy.
If there are any iterators which you think can be easily made const, I'd suggest making a PR doing so.
2 Likes
Like everything else in Rust: When it's done.
Feel free to fund contributors if you have things you'd like to see done faster 
6 Likes