How to use Racket languages?

[Lawrence Bottorff]

I thought I knew how to do this, i.e., if I wanted to have a certain Racket
language in my org-mode code block, just do something like this:

#+begin_src scheme :session sbh1 :results output
#lang simply-scheme
(se (butlast (bf "this"))
    "world")
#+end_src

but I get errors

#+RESULTS:
#+begin_example
stdin::837: read: `#lang` not enabled
  context...:
   read-lang31
   . . .

Going over to the REPL

racket@> #lang racket
stdin::438: read-syntax: `#lang` not enabled
  context...:
   read-lang31
   read-syntax3
  . . .

I thought this was just a simple matter, but apparently not. What can I do
to get these Racket languages working?

LB