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greghendershott / rackjure

Provide a few Clojure-inspired ideas in Racket. Where Racket and Clojure conflict, prefer Racket.
BSD 2-Clause "Simplified" License
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let #fn work in the repl using #:language-info and runtime-config.rkt #46

Closed AlexKnauth closed 9 years ago

AlexKnauth commented 9 years ago

see https://github.com/greghendershott/rackjure/issues/45 One reason not to do this is that if a rackjure module is required from a non-rackjure module, it will still update the current-readtable, so the current-readtable in the non-rackjure module would be affected.
Edit: Using either a configure-runtime submodule or the #:language-info option and a runtime-config.rkt avoids this problem.

greghendershott commented 9 years ago

I've seen e.g. Typed Racket define #%top-interaction to provide REPL behavior like printing the type of the result.

But IIUC #%top-interaction is too late in this case -- the read has already happened?

I forget, had you asked about this on the Racket mailing list? Our use case doesn't seem very unusual. Maybe there's some other way to accomplish this. Or if not, Racket could add this? Otherwise it seems like a small but significant hole in the "language for making languages" story.

greghendershott commented 9 years ago

I can't believe I overlooked this! This is a great improvement. Merged; thanks!

AlexKnauth commented 9 years ago

Oh, I did something similar for at-exp, but elibarzilay commented and said it might be better to just update the readtable (once) instead of updating current-read-interaction to be a function that creates a new readtable every time. So do you think it would be better to do that, or keep this? see: https://github.com/plt/racket/pull/811#issuecomment-61992444 https://github.com/plt/racket/pull/811#issuecomment-62090573

greghendershott commented 9 years ago

Ah, OK. So you mean that the lang/runtime-configure.rkt could be simplified as in https://github.com/AlexKnauth/racket/commit/e972753b59755c3a0ff457748371d48e0a37a5ed ?

From this:

(define (configure data)
  (define old-read (current-read-interaction))
  (define (new-read src in)
    (parameterize ([current-readtable (make-lambda-readtable (current-readtable))])
      (old-read src in)))
  (current-read-interaction new-read))

To just this:

(define (configure data)
  (current-readtable (make-lambda-readtable (current-readtable))))

Is that correct?

AlexKnauth commented 9 years ago

Yes, if you think it's a good idea.

greghendershott commented 9 years ago

Done with commit 05e57f7. Thanks again!