> Aren't you adding some assumptions about the implementation in your comment?
You'd have a point if they were talking about implementation semantics, but they're talking about language semantics. A Scheme program can assume TCE, a CL program can not, an SBCL program can.
It's not clear to me that the person I replied to was talking about language semantics. The phrasing of that comment would have taken the form "may not" or "can't assume", but instead asserted that you can write some code that's guaranteed to run differently, which is implementation semantics.
You'd have a point if they were talking about implementation semantics, but they're talking about language semantics. A Scheme program can assume TCE, a CL program can not, an SBCL program can.