Post demystifying IndexByType

[Andarist]

This is a strong draft of the post - it needs to be polished before we can publish it.

I think it has the potential of splitting into two parts:

1. typegen intro: outline the problem, describe the goals (stuff up to the "indexing" header)
2. IndexByType demystified (the big part from the "indexing" header)

We could make this whole thing a series of blog posts about the typegen's internal machinery. Not every blog post has to be as long as this one - some tricks used in there are much simpler, or at least they can be described much quicker. And I think that each blog post should be its own thing, it's not worth squeezing two different tricks into a single post or something like that.

I would be very grateful for some initial feedback and help with the structure, language, etc

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[laurakalbag]

I think the structure is fine as a long read like this will really appeal to folks who like to know the details, which is really the point of the post!

A few more headings might help give some navigational landmarks which will also appear in the Table of contents sidebar. I’ve noted where I think we might need them, but you know best.

Most of my suggestions are minor grammatical fixes, some typography and occasionally trying to make it clearer what you’re referring to when you say “it”, “this”, or “that.” Please feel free to dismiss or ignore any you disagree with, and let me know if you want a re-review at any point.

Let me know when you’ve confirmed the title and I’ll make a matching open graph image so it looks pretty on social media.

[laurakalbag]

Suggested change

	It's also worth noting that our check isn't literally checking if `T[K]["type"]` is exactly the same as `K`. It's checking if it is a subtype of `K`. But we are working on a very strong, practical, assumption that each member of the union has a literal type as its type (or a union of those) and none of them is using `{ type: string }`.
	It’s also worth noting our check isn’t literally checking if `T[K]["type"]` is exactly the same as `K`. Instead, it’s checking if `T[K]["type"]` is a subtype of `K`. But we’re working on a very strong practical assumption that each member of the union has a literal type, as its type (or a union of those) and none of them is using `{ type: string }`

[laurakalbag]

Perhaps we could finish off with a short conclusion/summary?

[Andarist]

Ye, I was thinking about adding some closing thoughts. What do you think about "please don't do it at home"? 🤣

[laurakalbag]

“I did this so you don’t have to” 😂

[Andarist]

that's a good one!

[Andarist]

Laura has suggested adding a subheading here: #81 (comment)