TL;DR: I tried to implement in CPython a frozendict here: https://github.com/Marco-Sulla/cpython
Long explaining: What is a frozendict? It's an immutable dict. The type was proposed in the past but rejected: https://www.python.org/dev/peps/pep-0416/ So why did I try to implement it? IMO, apart the considerations in PEP 416, a frozendict can be useful: - as a faster base for types.MutableMappingProxy - as a substitute of namedtuple - as set values - as a faster dict. Indeed a frozendict does not need views. Keys, values and items can be cached and could be a subclass of frozendict that implements also the set API (values apart). A possible problem is that frozendict requires more memory, since the hash is cached. My implementation is very naif. I tried to do the simplest thing, without any speed improvement. I haven't added frozendict in marshal, and the pickle implementation is very raw... Furthermore, I didn't touch the AST parser at all, and I did not add any test for Python or the C API in the battery, but I've done my tests apart, in pytest. PS: I used for tests and benchmarks a little modified version of the tests for my Python implementation of frozendict: https://github.com/Marco-Sulla/python-frozendict/tree/master/test . The results are interesting. A CPython builtin frozendict is faster in every bench that immutables.Map, that uses the HAMT algorithm. and was proposed as alternative in PEP 603: https://www.python.org/dev/peps/pep-0603/ . Maybe because I implemented it in CPython and immutables.Map is a C extension. -- https://mail.python.org/mailman/listinfo/python-list
