Great paper. The blog post by Yuri Iozzelli mentioned in the discussion section is also fantastic—which I miraculously discovered from Yuri directly, after desperately asking about restructuring control flow on Discord… even though I had already wasted a few hours reading LLVM source code.

The day I learned he was a PL person… my mind was blown. His videos on playful applications of CS inspired me in high school (long before I knew PL research was a thing)

`::` can be used to supply annotations which are dynamically checked, while `:~` can be used to get static information from annotations without a runtime cost. There are also (perhaps surprisingly) interfaces, with analogues of popular type classes like Show and Eq.

Types, in _my_ Lisp dialect? Many of the safety guarantees and documentation benefits of type systems are achieved in Rhombus through “annotations” (read: contracts). Classes come with their own annotations (and _static_ checks!), and `||` can be used analogously to sums.