I think laziness-by-default is now mostly seen as a sub-optimal choice for general-purpose programming languages, and the complicated cost-model is one of the r

I think laziness-by-default is now mostly seen as a sub-optimal choice for general-purpose programming languages, and the complicated cost-model is one of the reasons. As far as I'm aware, even SPJ would agree with this (please correct me if I'm wrong). Eager evaluation as default and lazy evaluation as option is a good compromise. (Scala offers this.)