agalatan

// See the flow link at the bottom, and the GIT comment below

// Good utils
type $If<X: boolean, Then, Else = empty> = $Call<((true, Then, Else) => Then) & ((false, Then, Else) => Else), X, Then, Else>;

type $Not<X: boolean> = $If<X, false, true>;
type $And<X: boolean, Y: boolean> = $If<X, Y, false>;
type $Or<X: boolean, Y: boolean> = $If<X, true, Y>;

// Unique, internal Symbols. Probably I can actually use JS's Symbol. Need to see how well Flow implements it

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?