[sesgoe]

There's a ton of motivation from a DX perspective -- Python type hinting's arguably least valuable feature is the autocompletion improvement that comes with it.

It's nice to be able to hit `.` in your editor and have the options for whatever object you're staring at pop into a list you can pick from. Similarly, for a `TypedDict`, you can hit `["` and just have all the possible key options autocomplete.

The bespoke dicts mostly come from early-days SQL queries akin to

  SELECT * FROM single_table

I wrote a small tool in Rust (yes, I was looking for an excuse to use Rust at work) first to create a giant `TypedDict` file that basically typed all the table rows in our primary database and then a small parser that reads our codebase for these trivial select * from single_table queries and adds `TypedDict` hinting for autocompletion purposes going forward.

So a line like:

  some_result = curs.fetchone()

becomes:

  some_result: SingleTable = curs.fetchone()

Then when you type:

  some_result["

You get a lovely list of auto-completed possible keys instead of having to go hunting through the table to remember what the column was called.

The other reasons we wanted to implement typing were all the main reasons you'd want a typed codebase in the first place. Shift a lot of mistakes to build-time instead of deployed-in-production time.