Environment as in #109. The direct purpose would be to have the Bel REPL be a program, and (in Bel tradition) be a small program. Something like this:

(def repl ()
  (awhen (read (prompt "> "))
    (print:bel it)
    (repl)))

Not sure it can be made quite that short, but it's an ideal to strive towards.

I also realized that a really good prompt would listen to keystrokes, not just characters from ins. In other words, it would listen to essentially another API (or at least not exclusively the ins character stream), in order to

• Move the cursor around on the input line
• Move through history (up and down)

and no doubt many more functions of essentially rlwrap.

(Hm, another issue with the example code above: I want it to abort on EOF/^D and the like, but not on empty string.)