catlifeonmars • 5 days ago

This is the same in JavaScript. There is “pure” Iterable protocol which produces an “impure” Iterator. Interestingly , for loops in JavaScript do not work directly with Iterators; to use in a for loop you must wrap an Iterator in an Iterable

1
codr7 • 5 days ago

Java is the same if I remember correctly, always felt like a design failure to me.

1 reply
masklinn • 5 days ago

It's especially dumb for Java, because Iterator could just have been a subtype of Iterable. That's basically what Python does, the iterator protocol requires also being an iterable[0]. And Rust just blanket implements IntoIterator for every Iterator without asking.

At least it's pretty easy to wrap an iterator in JS:

  {[Symbol.iterator]: () => it}
[0] which in the rare case you implement an iterator entirely by hand will be a trivial `return self`, so much so that `collection.abc.Iterator` just provides that)