Yes, that makes a lot of sense to me. That way you...

# stdlib

[mplatvoet]

Yes, that makes a lot of sense to me. That way you can also have that the “regular” counterparts filter and map etc always do lazy evaluations, so no matter whether something is an Iterable or a Sequence, it will be consistent behaviour. The behaviour is not dependent on the type of the receiver.

That does leave your concern about accidental reevaluations open as commonly seen with naive C# Linq programming. E.g. where some DB query is fired over and over again because someone forgot to create a snapshot of the results. However, I think a consistent API will make it easier to cope (educate) with such issues.