Design goals:

• NOT an implementation of the ISO C++ standard library, but instead an experiment to see what a stdlib without backwards compatibility requirements might look like
• design-wise copy the Python standard library's APIs whenever possible
• minimize build times
• a single header for the most common things
• KISS
• needs to be performant, but not "super optimized" to the hilt
• Can use existing C libraries like pcre but not C++ libraries

Do both of these:

• Maintain perfect API and ABI compatibility
• Make it possible to change both in arbitrary ways

This seems impossible but is in fact fairly easily achievable:

• Put everything under pystd<year> namespace

• When release happens, copy all files from foo<year>.[ch]pp to foo<year+1>.[ch]pp and rename the namespace accordingly

• The old version remains forever frozen in time

• Arbitrary changes can be done to the new version

Anyone who needs to interoperate with code using the old versions can #include the old header and use things from its namespace as needed.

Tested with GCC and Clang on Linux and macOS. Does not work with MSVC as it has not yet added support for pack indexing.