Drop support for Python 3.10, require Python >= 3.11

[EwoutH]

Starting development for Mesa 3.1 and following SPEC 0 we can drop Python 3.10 support and require Python 3.11 or higher for future development. This allows adopting more modern Python features and simplifies the testing and CI configurations.

See the Python 3.11 release notes: https://docs.python.org/3/whatsnew/3.11.html

The 3.0.x release series will keep supporting Python 3.10.

Summary – Release highlights

Python 3.11 is between 10-60% faster than Python 3.10. On average, we measured a 1.25x speedup on the standard benchmark suite. See Faster CPython for details.

New syntax features:

• PEP 654: Exception Groups and except*

New built-in features:

• PEP 678: Exceptions can be enriched with notes

New standard library modules:

• PEP 680: tomllib — Support for parsing TOML in the Standard Library

Interpreter improvements:

• PEP 657: Fine-grained error locations in tracebacks
• New -P command line option and PYTHONSAFEPATH environment variable to disable automatically prepending potentially unsafe paths to sys.path

New typing features:

• PEP 646: Variadic generics
• PEP 655: Marking individual TypedDict items as required or not-required
• PEP 673: Self type
• PEP 675: Arbitrary literal string type
• PEP 681: Data class transforms

Important deprecations, removals and restrictions:

• PEP 594: Many legacy standard library modules have been deprecated and will be removed in Python 3.13
• PEP 624: Py_UNICODE encoder APIs have been removed
• PEP 670: Macros converted to static inline functions

[EwoutH]

@quaquel two things you might find cool we can start using when we require Python 3.11:

1. Exception Notes (PEP 678)
   We could use add_note() to provide additional context for errors in Mesa. This would be particularly useful for:

• Adding model state information when errors occur
• Providing hints about common configuration mistakes
• Adding contextual information about agent states

For example:

try:
    # Some model operation
except ValueError as e:
    e.add_note(f"Current model step: {self.steps}")
    e.add_note(f"Number of active agents: {len(self.agents)}")
    raise

2. Self Type (PEP 673)
   We can use the new Self type annotation to better annotate methods that return instances of their own class, particularly useful in Agent and Model classes:

from typing import Self

class Agent:
    def clone(self) -> Self:
        return copy.deepcopy(self)

Those notes really seem handy!

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 -1.9% [-2.7%, -1.1%]	🔵 -0.4% [-0.6%, -0.3%]
BoltzmannWealth	large	🔵 -2.0% [-2.5%, -1.5%]	🔵 -0.6% [-1.7%, +0.3%]
Schelling	small	🔵 -0.4% [-0.9%, +0.1%]	🔵 +0.3% [-0.0%, +0.7%]
Schelling	large	🔵 +0.4% [-0.7%, +1.4%]	🔵 +1.8% [+0.4%, +3.0%]
WolfSheep	small	🔵 -0.3% [-0.8%, +0.1%]	🔵 +1.1% [+0.8%, +1.3%]
WolfSheep	large	🔵 -6.2% [-9.7%, -2.9%]	🔵 -4.5% [-8.4%, -0.1%]
BoidFlockers	small	🔵 +0.6% [-0.1%, +1.3%]	🔵 +0.3% [-0.5%, +1.1%]
BoidFlockers	large	🔵 +0.3% [-0.5%, +1.2%]	🔵 +0.3% [-0.4%, +0.9%]

[EwoutH]

Not that this is not a breaking change by the way, because the requires-python = ">=3.11" prevents anyone from installing Mesa 3.1+ with Python 3.10 or lower. They still can install Mesa 3.0.x, which is fully compatible.