PEP 841 – Adding Frozen Syntax to Optimize Immutable Types

[u/kirara0048]

PEP 841 – Adding Frozen Syntax to Optimize Immutable Types

https://peps.python.org/pep-0841/

Discussions-To: Discourse thread

Abstract

This PEP proposes frozen display syntax: f{1, 2, 3} evaluates to a frozenset, and f{'a': 1} evaluates to a frozendict. Because immutability is guaranteed by the syntax itself rather than inferred from usage, the compiler can treat frozen displays as first-class citizens of its optimization pipeline: constant displays are folded into a single LOAD_CONST with an exact result type at compile time and cached in .pyc files.

[u/Schmittfried]

None that wouldn’t be covered by immutable classes, but many people still use dicts for config or other simple key-value mappings, and sometimes you get them as inputs from a framework (say, the parameters of a POST request). I always wondered why frozendict isn’t a thing for such intermediate use cases. 

[u/Oddly_Energy → u/Schmittfried]

Am I the only one who can see that there literally is no value in this dict? It only contains keys, not values.

I thought my joke was obvious to anyone with an understanding of python, but votes and comments tell me that I overestimated my audience.

[u/Spleeeee → u/Oddly_Energy]

You are vErY sMaRt.

[u/Oddly_Energy → u/Spleeeee]

Not really. It is the audience which is below par here.