This issue is intended to track the status of Python 3.8 core features as implemented by MicroPython.

Python 3.8.0 (final) was released on the 14 October 2019. The Features for 3.8 are defined in PEP 569 and a detailed description of the changes can be found in What's New in Python 3.8.

• PEP 570, Positional-only arguments
• PEP 572, Assignment Expressions; Done, see #4908
• PEP 574, Pickle protocol 5 with out-of-band data
• PEP 578, Runtime audit hooks
• PEP 587, Python Initialization Configuration
• PEP 590, Vectorcall: a fast calling protocol for CPython

Misc

• f-strings support = for self-documenting expressions and debugging; Done, see #7649

Other language changes

• A continue statement was illegal in the finally clause due to a problem with the implementation. In Python 3.8 this restriction was lifted; Done, see 82c494a97e874912e7eb23d2f03f39212e343fb3
• The bool, int, and fractions.Fraction types now have an as_integer_ratio() method like that found in float and decimal.Decimal
• Constructors of int, float and complex will now use the __index__() special method, if available and the corresponding method __int__(), __float__() or __complex__() is not available
• Added support of \N{name} escapes in regular expressions
• Dict and dictviews are now iterable in reversed insertion order using reversed()
• The syntax allowed for keyword names in function calls was further restricted. In particular, f((keyword)=arg) is no longer allowed
• Generalized iterable unpacking in yield and return statements no longer requires enclosing parentheses
• When a comma is missed in code such as [(10, 20) (30, 40)], the compiler displays a SyntaxWarning with a helpful suggestion
• Arithmetic operations between subclasses of datetime.date or datetime.datetime and datetime.timedelta objects now return an instance of the subclass, rather than the base class
• When the Python interpreter is interrupted by Ctrl-C (SIGINT) and the resulting KeyboardInterrupt exception is not caught, the Python process now exits via a SIGINT signal or with the correct exit code such that the calling process can detect that it died due to a Ctrl-C
• Some advanced styles of programming require updating the types.CodeType object for an existing function
• For integers, the three-argument form of the pow() function now permits the exponent to be negative in the case where the base is relatively prime to the modulus
• Dict comprehensions have been synced-up with dict literals so that the key is computed first and the value second
• The object.__reduce__() method can now return a tuple from two to six elements long

Changes to MicroPython built-in modules

• asyncio
  • asyncio.run() has graduated from the provisional to stable API
  • Running python -m asyncio launches a natively async REPL
  • The exception asyncio.CancelledError now inherits from BaseException rather than Exception and no longer inherits from concurrent.futures.CancelledError
  • Added asyncio.Task.get_coro() for getting the wrapped coroutine within an asyncio.Task
  • Asyncio tasks can now be named, either by passing the name keyword argument to asyncio.create_task() or the create_task() event loop method, or by calling the set_name() method on the task object
  • Added support for Happy Eyeballs to asyncio.loop.create_connection(). To specify the behavior, two new parameters have been added: happy_eyeballs_delay and interleave.

• gc - get_objects() can now receive an optional generation parameter indicating a generation to get objects from
  • (Note, though, that while gc is a built-in, get_objects() is not implemented for MicroPython)

• math
  • Added new function math.dist() for computing Euclidean distance between two points
  • Expanded the math.hypot() function to handle multiple dimensions
  • Added new function, math.prod(), as analogous function to sum() that returns the product of a ‘start’ value (default: 1) times an iterable of numbers
  • Added two new combinatoric functions math.perm() and math.comb()
  • Added a new function math.isqrt() for computing accurate integer square roots without conversion to floating point
  • The function math.factorial() no longer accepts arguments that are not int-like

• sys - Add new sys.unraisablehook() function which can be overridden to control how “unraisable exceptions” are handled

(Changes to non-built-in modules will need to be documented elsewhere.)