niieani/typescript-vs-flowtype

Add diff type for typescript

sanex3339 opened this issue · 6 comments

sanex3339 commented

Now we can add diff type to the TS section

type Diff<T extends string, U extends string> = ({[P in T]: P } & {[P in U]: never } & { [x: string]: never })[T];
niieani commented

Can you link to the source of this? Thanks.
Also, PR's are welcome.

pelotom commented

It's not quite the same since Diff subtracts unions of literals, whereas $Diff subtracts objects. Omit, based on Diff, is closer:

type Omit<T, K extends keyof T> = {[P in Diff<keyof T, K>]: T[P]};

Omit<{ a: string, b: number }, 'a'> // = { b: number }
niieani commented

I'd appreciate a PR to the README. As long as there are no caveats with Omit (I remember initially there used to be), we can add it.

niieani commented

TS 2.8 now has official support. I'll close this issue and make an umbrella issue for 2.8.

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