Proposal: Give annotative names to Key and Value in Dictionary to improve code readability

[palazzo-train]

Summary

Add new syntax in Dictionary declaration to annotate the key and value for readability

Motivation

in C# struct, we can know clearly the purpose of a variable by it's name. For example,

public struct Book
{
    public string title;
    public string author;
}

Then, i know b.title is a type of string and it's referring to title.

However in C# dictionary, we can only specify the type

Dictionary<string,string> d

Can we make the code more readable such that the key of the dictionary is type of string and it is referring to title, and the value is type of string and it is referring to author? That means, other people can easily know that d["J.R.R. Tolkien"] is a wrong use of the dictionary when reading the code.

Proposed Syntax

from

Dictionary<string,string>

to

Dictionary<title@string,author@string>

The title and author are only annotation to the type string in the key and the type string in the value. It does not alter anything as of current Dictionary, but the annotation title and author will become some informative meta data used by IDE

[YairHalberstadt]

One way to do this might be 1 element tuples:

Dictionary<(string title),(string author)>

Ideally 1 element tuples would be backed by the Actual element type, not ValueTuple, allowing you to freely cast from Dictionary<string, string> to Dictionary<(string title),(string author)>.