> Python really needs to take the Typescript approach of "all valid Python4 is valid Python3"
It is called type hints, and is already there. TS typing doesn't bring any perf benefits over plain JS.
It is called type hints, and is already there. TS typing doesn't bring any perf benefits over plain JS.
class Foo:
__slots__ = ("a", "b")
a: int
b: float
* a user can define subtype `class my_int(int)`, so you cannot optimize the layout of `class Foo`
* the builtin `int` and `float` are big-int like numbers, so operations on them are branchy and allocating.
and the fact that Foo is mutable and that `id(foo.a)` has to produce something complicates things further.
Therefore Python has no use for TS-like superset, because it already has facilities for static analysis with no bearing on runtime, which is what TS provides.
1) Add TS like language on top of Python in backwards compatible way
2) Introduce frozen/final runtime types
3) Use 1 and 2 to drive runtime optimizations
From all posts it looks like what OP wants is a different language that looks somewhat like Python syntax-wise, so calling for "backwards-compatible" superset is pointless, because stuff that is being demanded would break compatibility by necessity.