[rydel]

Is I wrote: IMO these language are not fully functional. TCO/TCE is crucial for operations on tree like data structures. And also as I wrote: it all depends in which context we are talking to. Scheme specification makes it clear that TCO/TCE is required. If I am not wrong, F# is the same thing as Scala, but in .Net world(?) - Scala cannot be treaded as clear functional, because it is for JVM which was not designed for functional programming. Surely, many languages can have more or less functional functionalities, but having a subset of properties which defines what is functional, cannot be treated as functional in the full sense.