I find it interesting that this is exactly what Perl6 tried to handle gracefully, both on the technical side (a type system that supports both static and dynamic typing) as well as on the practical side (a re-implementation from scratch with some measure of interoperability).
However, they did not set out to just design the next version of Perl, but the last version, reasoning that if you have proper extension mechanism in place, you won't have to do a reboot ever again.
This resulted in gradual typing (which sometimes needs to fall-back to runtime checks), a pluggable syntax with extensible grammar, a flexible meta-object protocol, default numeric types that are objects (rationals or bigints), lazy list, reified language construct (variables as container objects) and other stuff that makes a straight-forward implementation horribly slow.
However, they did not set out to just design the next version of Perl, but the last version, reasoning that if you have proper extension mechanism in place, you won't have to do a reboot ever again.
This resulted in gradual typing (which sometimes needs to fall-back to runtime checks), a pluggable syntax with extensible grammar, a flexible meta-object protocol, default numeric types that are objects (rationals or bigints), lazy list, reified language construct (variables as container objects) and other stuff that makes a straight-forward implementation horribly slow.