Patterns and Match

- patterns
- refutable vs irrefutable
- match
- Sequence type
- ... except for dynamic index signatures where it types as V | undefined (via dynamic.find)
- ranges: ..
- switch still works but match encouraged

- let, let-else
- if let
- while let
- match guards

- No Computed Keys
- no obj[expr] where expr is dynamic
- destructure dynamically with { [key]: value }?

enum State { Pending, Running, Complete }
declare const state: State;

const label = match (state) {
    State.Pending => "pending",
    State.Running => "running",
    State.Complete => "complete",
};