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by jjwiseman
2828 days ago
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There is a group of people that love to say this ("If you're not using a repl or restarting your repl all the time, you're doing it wrong"), but I've been using Lisp for more than 20 years and I don't agree. A repl is nice, and I use one often, but it does have tradeoffs. One is persistent state--It can be quite easy to get your repl into a state where your code works, but if you run the app from scratch it doesn't because definitions are out of sync (e.g. you renamed a function, but forgot to change the name at a call site, so you end up calling an old version of the function.) Developing in a repl is nice, but it's not the only allowed or legitimate or even good way to do development in Lisp or other dynamic, interactive languages. Clojure has an issue with slow startup (another tradeoff made for good reasons that don't fit everyone's situation)--denigrating other people's development approaches doesn't solve that, it comes off as defensive. |
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Me neither, and I also carry decent Lisp cred.
I know what I'm doing to the extent that I can write a bunch of code in a file, and have it work, more or less.
If I experiment with changes to code, I want to see the diff (as in git diff).
Actually developing in a REPL seems very scatter-brained; you don't know what you're running since you've been mutating things left and right.
Those that develop in a REPL actually develop in some kind of text editor which sends expressions to the REPL; that's what allows them to save the code properly to a file. Problem is, you now have three versions of the code to keep straight: editor, file and image.
Okay, so you have massaged things into working. Well, which is the code that is working? Obviously, the code that is in the image. But of the textual codes does it correspond to? If you just save the content of every edit buffer to disk, is the code on disk exactly that code that is working in the image?
Even if I have to work with a running image (say there is a lot of state that is difficult to reproduce from a clean start), I'm still going to work with some files, which I will edit and completely save to disk, and load all together as a unit into the running image, instead of evaluating individual expressions out of an edit buffer.