* The printing of error message has been improved to display the code source responsible of the error outside of the REPL.
* Some probable beginner errors (like discarding a non-applied function with `ignore`) now raises a warning.
* Type name captures should not happen anymore in error messages: no more `val x: int` is not included in `val x: int` where `int` refers silentiously to different types.
* A handful of typing errors has been fixed to speak to users and not the compiler developers (no more "unexpected existentials" for instance).
* Some compiler internal change to make it much easier to use the typing context when explaining a type error. This is not used much yet, but I hope to improve the scope related type errors in the next versions.
A few months ago someone on HN mentioned that error messages would be greatly improved in this release, which would make learning OCaml much easier.
Does anyone have more details on this?