Comment by perrygeo

In a language that is otherwise as simple as it could possibly get away with (no `if`!), `use <-` initially feels like magic and somewhat out of place.

But take look at nested callback code, the pyramid of doom, and you see why it's pragmatically necessary. It's a brilliant design that incorporates just enough metaprogramming magic to make it ergonomic. The LSP even lets you convert back and forth between nested callback style and `use`, so you can strip away the magic in one code action if you need to unravel it.