@khalidabuhakmeh yes, I'm using ISpanParseable<T> instead of TypeConverter which makes it fully aware of the types/methods that it needs to compile. Often existing command line parsers are including stuffs like declaring options by putting attributes on fields/properties and other similar stuffs, so they have to rely more heavily on System.Reflection and are are usually less NativeAOT friendly. Some are doing source generator, and while it could be nice, it feels overkill.