> That is much more complicated to implement, though, and requires environments as first-class objects.
Given the interpreted nature of Arc, first class environments shouldn't be too hard to implement, but in a compiled implementation it would be a lot more difficult.
They could not be implemented on top of the existing arc-to-scheme translator, because that's what it is: an arc-to-scheme translator, not an interpreter. Scheme doesn't have first-class environments, so we can't shove them into arc without writing a full-fledged arc interpreter.
If the environments are temporaries created only while processing macros, and are discarded afterwards, they don't necessarily have to be difficult for compilers.
