The language eleven years after 3.0
On 14 October 2019 the Python Software Foundation released Python 3.8, under Łukasz Langa as Release Manager. Eleven years after Python 3.0’s release (December 2008), the line is mature, stable, with a boundless library ecosystem. 3.8 consolidates several trajectories opened by earlier releases, with thoughtful new syntax additions.
3.8 is a Regular Release with support through October 2024 (five years) under the standard support cycle. The transition from Python 2 — formally ended 1 January 2020 — is by now completed in most production projects.
Walrus Operator (PEP 572)
The most debated syntactic novelty is the walrus operator :=, described by PEP 572. It allows assignment and evaluation in a single expression:
# Before
line = file.readline()
while line:
process(line)
line = file.readline()
# With walrus
while line := file.readline():
process(line)Or in filters and comprehensions:
filtered = [y for x in data if (y := compute(x)) > threshold]The public discussion on PEP 572 was heated — Guido van Rossum (historic BDFL) expressed support and even declared the intensity of the debate led him to decide to step down from leading the language (announcement July 2018, transition to Steering Council governance). 3.8 is the first post-BDFL release and the first to formally include the new operator.
Positional-only parameters (PEP 570)
PEP 570 introduces the / syntax to mark parameters as positional-only:
def greet(name, /, greeting="Hello"):
return f"{greeting}, {name}!"
greet("Anna") # OK
greet("Anna", greeting="Hi") # OK
greet(name="Anna") # TypeError: name is positional-onlyThis construct aligns Python with built-in functions (e.g. len(obj, /)) and allows safe refactors: renaming a parameter is not a breaking change if it is positional-only.
Self-documenting f-string
Small but welcome: f"{x=}" produces x=value, useful for debugging:
x = 42
y = [1, 2, 3]
print(f"{x=}, {y=}") # x=42, y=[1, 2, 3]Evolved typing
The typing module gains significant constructs:
TypedDict (PEP 589)
Types dicts with known schema:
from typing import TypedDict
class User(TypedDict):
name: str
age: int
active: bool
u: User = {"name": "Anna", "age": 30, "active": True}Final (PEP 591)
Marker for non-overridable variables/methods:
from typing import Final
MAX_RETRIES: Final = 5Literal (PEP 586)
Types accepting only specific values:
from typing import Literal
def log(level: Literal["debug", "info", "error"]) -> None: ...Protocol (PEP 544)
Structural subtyping — formalised “duck typing”:
from typing import Protocol
class Drawable(Protocol):
def draw(self) -> None: ...
def render(obj: Drawable) -> None:
obj.draw()Python typing, started with PEP 484 in 2015, reaches in 3.8 a maturity that enables type checkers like mypy, pyright (Microsoft), pyre (Facebook), pyre-check to work on complex enterprise codebases.
Performance
3.8 includes diffuse optimisations:
- Shared cache for module metadata — faster imports
- Optimised LOAD_GLOBAL opcode
- asyncio run() and Task improvements
- pickle Protocol 5 (PEP 574) — out-of-band buffers, zero-copy for large data
Other contributions
- multiprocessing.shared_memory (related to PEP 574) — cross-process shared memory without serialisation
- reversed() for dict — reverse-order iteration
- Math constants —
math.prod(),math.isqrt(),math.perm(),math.comb() - sys.platform for Android
- f-string ’=’ specification
Breaking changes
3.8 introduces no massive breakage but:
- Python 2 is fully deprecated — EOL 1 January 2020
- Some modules deprecated from 3.3/3.4 are removed
- DeprecationWarning visible by default in
__main__
Ecosystem impact
Main libraries update to leverage novelties:
- Django — walrus and positional-only support in internal methods
- FastAPI (growing from 2018) — deep integration with TypedDict/Protocol typing
- Pydantic — field validation with Literal
- SQLAlchemy 2.x (in development) — extensive use of TypedDict and Protocol
- pytest, Flask, Celery — progressive updates
In the Italian context
Python 3.8 enters Italian projects at the usual pace:
- Data science — analytics teams adopt rapidly (pandas, NumPy, Jupyter ready)
- Web — Django and FastAPI in production
- ML/AI — TensorFlow, PyTorch compatible
- PA — new Python projects adopt 3.8; existing 3.6/3.7 projects progressively migrate
References: Python 3.8.0 (14 October 2019). Łukasz Langa as Release Manager. PEP 572 (walrus), PEP 570 (positional-only), PEP 589 (TypedDict), PEP 591 (Final), PEP 586 (Literal), PEP 544 (Protocol), PEP 574 (pickle 5). Python Steering Council (post-BDFL, 2018). Python Software Foundation.