Comment by wcrichton

This is awesome, and a big step forward for OCaml. Only criticism is that it seems difficult/awkward that you need different functions/values for each phase. In other staged macro systems (Scala/LMS, Rust/Compiler Plugins) you can refer to the same functions in any phase, and you can also splice values from the staging phase into the runtime phase without explicit use of a function like Expr.of_int.