Dart will not actually optimize based on type annotations; it will optimize based on watching what the actual internal types of objects are, and generating spec

Dart will not actually optimize based on type annotations; it will optimize based on watching what the actual internal types of objects are, and generating specialized code for the common cases. From an interview with Lars Bak: http://gototoday.dk/2011/10/10/lars-bak-on-dart/ http://gototoday.dk/2011/10/10/lars-bak-on-dart/