The Roslyn C# compiler also doesn't throw anything away - you can recreate the source from the AST, completely with white-space and comments. This is necessary

The Roslyn C# compiler also doesn't throw anything away - you can recreate the source from the AST, completely with white-space and comments. This is necessary to support safe refactorings, so I don't think this is a novel idea. IntelliJ must have supported something like this for ages. Bosque sounds like something beyond Roslyn, but it is not clear to me what.