Loader Examples

1. markdown loader (extract fenced items and source-map)
2. TypeScript loader
3. CoffeeScript loader
4. npm: scheme loader (`import "npm:blah"`) globally installs (if necessary), then redirects to location.
5. https loader
6. tar loader: `import "x.tar/file"` reads from tar file

Critically: they should all compose together:

`import "npm:pizza/x.tar/y.ts"`