The innovative ideas in programming languages design may have been known for many years, but at least half are cleverly not incorporated into mainstream languages like Python or Ruby, and don't get me started on Java.

Language design, more than anything, seems to be a field where using actual academic research is passé. C# seems to be the one rare exception among the popular languages. On other platforms, the innovative ideas are all stuck in less popular languages like Scala, OCaml or Haskell.