5 ms·

Racket is a really exciting language, especially with its focus on building small languages to solve problems. However, where it fails for me is in its lack of

• sigstoat 9y ago
  > When I investigated it, there seemed to be no way to actually connect a repl to a running program. i (poorly) implemented conditions for racket once, including the ability to drop into a repl at the point of error. so i think you could put in place some macros that would let you get at a repl wherever you wanted. probably not the sort of thing to leave in place all the time, though > Unlike with common lisp or clojure, with racket if you make changes to your code you have to restart the REPL, which destroys your state. that's a different issue. i believe matthias has commented on the mailing list (some years back) that the semantics associated with doing something like that are a mess, and that's why they weren't interested in implementing it.
  • mjmein 9y ago
    To me, being able to make changes to your code while keeping the current state in the REPL is key to interactive development. My workflow is generally to build up state, and then experiment with functions on that state until I get the correct output. This workflow is very natural in Clojure, Common Lisp and even Python (with IPython and autoreload). However, in Racket you have to restart everything on every change. This works ok for smaller applications, but if for example, your state is a large dataset that you pull from a remote database, it becomes a little more difficult. There are possibly workarounds, and I'm not saying that Racket is bad because of this. There are definite advantages to this approach, mainly for keeping everything simple and predictable. However, this was a roadblock for me, and the main reason why I didn't spend more time working on it. I also miss the ability to make changes to code, refresh the browser and instantly see the changes (instead of having to restart the server after each change). Here's a good discussion (in my opinion) of what makes a good REPL for interactive development: http://vvvvalvalval.github.io/posts/what-makes-a-good-repl.html http://vvvvalvalval.github.io/posts/what-makes-a-good-repl.h...
    • stonemetal 9y ago
      It isn't in DrRacket by default but it is a common enough requested feature that they keep an example of how to add it in the documentation. https://docs.racket-lang.org/drracket/Keyboard_Shortcuts.html#%28part._.Sending_.Program_.Fragments_to_the_.R.E.P.L%29 https://docs.racket-lang.org/drracket/Keyboard_Shortcuts.htm...
      • mjmein 9y ago
        Thanks. Do you know if it works with the module system - for example, if I edit function definition in a module, and then send that module definition to the REPL, would any code using that module start using the new definition?
        • bad_login 9y ago
          It works in geiser-mode, i don't know if it works with drracket or racket-mode. http://docs.racket-lang.org/guide/eval.html?q=namespace#%28part._.Namespaces_and_.Modules%29 http://docs.racket-lang.org/guide/eval.html?q=namespace#%28p...
    • sillysaurus3 9y ago
      I'm surprised no one has mentioned geiser. It sounds like exactly what you want for racket. http://nongnu.org/geiser/geiser_3.html http://nongnu.org/geiser/geiser_3.html
      • pera 9y ago
        There is also racket-mode (available on MELPA): https://github.com/greghendershott/racket-mode https://github.com/greghendershott/racket-mode
        • peatmoss 9y ago
          This is what I use. I find it quite comfortable / very easy to get going.
• maxiepoo 9y ago
  I believe this is a design decision, because relying on some enormous implicit repl state and updating the code in place is a good way to get yourself into states that are impossible to reach in an actual running program. Racket is a functional language and it is their belief that you should just make predictable ways to startup your interactive development than rely on the entire state of some repl image.
  • pera 9y ago
    I'm not sure if this is exactly what you are talking about, but with racket-mode in Emacs you can write some program, run it (C-c C-k), then add some s-expr and evaluate only that (C-x C-e) in the current context.
  • mikelevins 9y ago
    You're right; it's a conscious decision. I had a little discussion with Eli Barzilay and Matthew Flatt about some related matters a little while back. It was a nice discussion, but image-based or live programming is just not something they found particularly compelling. It pretty much keeps me from using Racket, and a bunch of other things that are otherwise very nice. Given a choice, I will always choose the tools that support me in building things by modifying programs as they run. I'm just happier and more productive that way. So one of my axes of optimization is selecting projects that enable me to work that way.
    • mjmein 9y ago
      My thoughts exactly. Once you are used to this way of developing, it is really difficult to be happy with less.
    • maxiepoo 9y ago
      Ah yes, I remember seeing an interaction that was probably yours, tried to find it for my comment, but never did.
      • elibarzilay 9y ago