> It's also especially irresponsible and hubristic to attempt to make a language that is seemingly compatible with both Python 2 and 3, because 1) I trust that if it was possible Guido and the other developers would have made it
It is possible actually, that's kind of the point! The interpreter I've been working on passes the 2.7 unit tests (i.e. those in Lib/test/), and as well as unit tests for the new features that have been backported from Python 3.
Even if you don't believe me, it's interesting to note that, e.g., while Python 3.0 was being developed, function annotations and keyword-only arguments coexisted with tuple unpacking. I built the code and ran it myself, in fact: https://twitter.com/naftaliharris/status/784421498291310592. Tuple unpacking was actually removed later, introducing the backwards incompatibility after the new functionality had been added. Timeline:
Oct 2006, keyword-only arguments.
Dec 2006, function annotations.
Mar 2007, removing tuple unpacking.
There was also a promising backport of keyword only arguments to CPython 2.6 (!) that was never merged, (http://bugs.python.org/issue1745), due to lack of follow-through.
It is possible actually, that's kind of the point! The interpreter I've been working on passes the 2.7 unit tests (i.e. those in Lib/test/), and as well as unit tests for the new features that have been backported from Python 3.
Even if you don't believe me, it's interesting to note that, e.g., while Python 3.0 was being developed, function annotations and keyword-only arguments coexisted with tuple unpacking. I built the code and ran it myself, in fact: https://twitter.com/naftaliharris/status/784421498291310592. Tuple unpacking was actually removed later, introducing the backwards incompatibility after the new functionality had been added. Timeline:
Oct 2006, keyword-only arguments.
Dec 2006, function annotations.
Mar 2007, removing tuple unpacking.
There was also a promising backport of keyword only arguments to CPython 2.6 (!) that was never merged, (http://bugs.python.org/issue1745), due to lack of follow-through.