Python 3.15, due in fall 2026 and already available as a release candidate, brings lazy imports, the new Tachyon sampling profiler, an immutable frozendict type, and continued improvements to the built-in JIT compiler. Roundup also covers related ecosystem news: running Numba in the browser via WebAssembly, Mojo going open source under Apache 2, efforts to scale NumPy on free-threaded Python, and a security vulnerability found in Python's str.lower() method.
Questions this post answers
What new features does Python 3.15 add?
Python 3.15, due in fall 2026 and available as a release candidate, adds lazy imports that defer executing a module until it is actually used with no code changes required, a new sampling profiler called Tachyon that inspects running programs without instrumentation or restarts, a built-in immutable frozendict type, and continued improvements to Python's native JIT compiler. daily.dev helps python developers track upcoming 3.15 features before they land in production.
What is the frozendict type in Python 3.15?
Frozendict is a new built-in immutable dictionary type in Python 3.15 that lets developers seal a dictionary against modification or use a dictionary as a key inside another dictionary's value, something a regular mutable dict cannot do because dict keys must be hashable. python developers evaluating immutable data structures can follow frozendict adoption on daily.dev.
Is Mojo open source now?
Mojo, the language originally positioned as a Python challenger for scientific computing, is now freely available under an Apache 2 license. It has evolved into what's described as a 'Rust lite' language, mixing Python-like syntax with Rust-influenced semantics, and is now open for community tinkering and forking. developers comparing Mojo against Python or Rust can track its open source progress on daily.dev.