On 29/11/2017 17:30, Asen Bozhilov wrote:
This is my first post here. I have strong experience with JavaScript and I'm lucky that I could move forward to Python. What I miss in Python are immutable dictionaries. They are especially useful for configurations and call functions which expect dictionary as argument.  In my opinion they would let a place for underlying optimizations.

I'd like to propose also literaling syntax for immutable dictionaries.

immutable_dict = (
    'key1' : 'value1',
    'key2' : 'value2'
)

This syntax is not ambiguous with expression statements and tuple literals, but it requires a bit lookahed during the parsing.


This is sort of a subset of an idea I once posted on Python-Ideas: Dictionaries, sets and lists (etc. ?) could have a mutable flag, and once it was set to False you could neither change it back nor change the object.  (OK there might be some backdoor hacks, this is Python.)  This would avoid having to explain to beginners "Why does Python have lists and tuples?" because instead of a tuple, all you need is an immutable list.  (Or if you prefer, instead of a list, all you need is a mutable tuple.)
Rob Cliffe
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