The initial concept was "value types" and we wanted a project name that was evocative of "value". Place names (even for mythical places) are good names since they cannot be trademarked. Hence, "value" => "val" => "Valhalla".
That was the type of interesting explanation I was wondering about. Thank you!
Because java has slowly been dying? ;-) no I don’t think that’s why (and java is still being used a lot I guess) but that was what jumped to mind first thing when I read “project valhalla”. Not the most PR friendly name!