He's probably referring to SPJ's work on the spineless tagless G-machine [1]. In truth, though, I think trying to incorporate Call-By-Push-Value into Haskell w

He's probably referring to SPJ's work on the spineless tagless G-machine [1]. In truth, though, I think trying to incorporate Call-By-Push-Value into Haskell would radically change the language unless there's some research in type theory that allows for the implicit Call-By-Need nature of Haskell to be extended into a form that can accommodate CBPV, which itself explicates a kind duality between Call-By-Name and Call-By-Value. If advancements have been made here, I'd love to hear about it. [1] http://research.microsoft.com/apps/pubs/default.aspx?id=67083 http://research.microsoft.com/apps/pubs/default.aspx?id=6708...