TIL: April 2020

function isFish(pet: Fish | Bird): pet is Fish {
  return (pet as Fish).swim !== undefined;
}
type Readonly<T> = {
  readonly [P in keyof T]: P[T];
}
heroku create
heroku buildpacks:add --index 1 heroku/nodejs
heroku buildpacks:add --index 2 heroku/ruby
git push heroku master
  1. by sobstel • April 2020 • blog archive