Valid point. On the other hand, not all one-liners launch a satellite.
^---- Sorry. The above line sat in the editor for 16 days, unnoticed by me.
Looks like there is a new REPL that is able to interpret Go source code line-by-line:
(Announcement on golang-nuts: https://groups.google.com/d/topic/golang-nuts/YTLZ1maIgFI/discussion)