Item 31: Push Null Values to the Perimeter of Your Types

https://effectivetypescript.com/2020/03/24/null-values-to-perimeter/

Wrong sentence in page 72?

Thanks for the great book, just skimming through it, but already gotten great advice! I feel like there is a small error on page 72 (or I am to dumb? sorry if thats the case). It says:

number[] is a subtype of readonly number[]
The sentence directly after says (Its easy to get this backwards- remember Item 7!)

I don't get how number[] is supposed to be a set with less possible values than readonly number[]?

readonly number[] lacks push, pop, etc..

I think the correct sentence should be readonly number[] is a subtype of number[]

All I Want for Christmas Is… These Seven TypeScript Improvements

Effective TypeScript: All I Want for Christmas Is… These Seven TypeScript Improvements

https://effectivetypescript.com/2022/12/25/christmas/

Welcome to Effective TypeScript!

Effective TypeScript: Welcome to Effective TypeScript!

https://effectivetypescript.com/2020/03/06/hello-world/

(old) Item 54: Know How to Iterate Over Objects

Item 54: Know How to Iterate Over Objects

https://effectivetypescript.com/2020/05/26/iterate-objects/

Item 54: Know How to Iterate Over Objects

https://effectivetypescript.com/2020/05/26/iterate-objects/

Item 41: Understand Evolving any

https://effectivetypescript.com/2020/03/09/evolving-any/

A TypeScript Perspective on Go: the 2021 Advent of Code

Effective TypeScript: A TypeScript Perspective on Go: the 2021 Advent of Code

https://effectivetypescript.com/2022/02/06/advent-of-code-2021-golang/

The `cacheLast` function is not implemented as expected

ch05-any/item-40-hide-unsafe-casts/hide-unsafe-casts-04.ts

Maybe it would be better to change the name of the function to memorize. cacheLast always sounds confusing.

function cacheLast<T extends Function>(fn: T): T {
  let lastArgs: any[]|null = null;
  let lastResult: any;
  return function(...args: any[]) {
    if (!lastArgs || !shallowEqual(lastArgs, args)) {
      lastResult = fn(...args);
      lastArgs = args;
    }
    return lastResult;
  } as unknown as T;
}

Is it better to use JSON.stringify(args) instead of (lastArgs, args) function?

The Seven Sources of Unsoundness in TypeScript

https://effectivetypescript.com/2021/05/06/unsoundness/

Use typed identity functions to guide type inference

Effective TypeScript: Use typed identity functions to guide type inference

https://effectivetypescript.com/2020/06/16/typed-identity-functions/

The Golden Rule of Generics

https://effectivetypescript.com/2020/08/12/generics-golden-rule/

Exclusive Or and the Optional never Trick

Effective TypeScript: Exclusive Or and the Optional never Trick

https://effectivetypescript.com/2021/11/11/optional-never/

Generic Tips Part 1: Use Classes and Currying to create new inference sites

Effective TypeScript: Generic Tips Part 1: Use Classes and Currying to create new inference sites

https://effectivetypescript.com/2020/12/04/gentips-1-curry/