https://issues.dlang.org/show_bug.cgi?id=15928
--- Comment #3 from Marc Schütz <schue...@gmx.net> --- Ah... I now remember the restriction that infinite ranges cannot be bidirectional. I think this was a conscious decision in order to get a simpler range hierarchy, but there was no fundamental reason to disallow it, right? This restriction simplifies things for chain(): if any of the individual ranges are infinite, the resulting chain cannot be bidirectional. --