Specifying language in <code> tags

Why isn't this supported? e.g. <code lang="scheme">

Even the specification recognizes this is a great idea, but doesn't formally implement it:
http://www.whatwg.org/specs/web-apps/current-work/multipage/text-level-semantics.html#the-code-element

This way you could implement a client that allows you to fold Lisp parentheses, unforce the indentation of Python, or put C++ in Comic Sans.

Will moot eventually switch to kareha or will he just delete the textreddits within an months