The docs of List.each() say This method is readonly safe. which I took to mean that it is not affected by subsequent changes to the list. But...

Void main() {
  list := [1, 2, 3, 4]
  list.each {
    list.remove(it)
  }
  echo(list)  // --> [2, 4]
}

Clearly the remove() statement affects the each() loop, which is not what I was expecting.

I can remedy the above by calling list.dup():

Void main() {
  list := [1, 2, 3, 4]
  list.dup.each {
    list.remove(it)
  }
  echo(list)  // --> [,]
}

But that is kindof what I thought each() did anyway.

Can someone confirm that I was wrong to expect the first bit of code to work? Cheers.

Readonly safe just means that it won't raise an exception if you try it with a readonly or immutable list. So if you want to mutate the list during iteration, you definitely want to duplicate it first.