Learn Rust by fixing code
Every exercise in the course is broken on purpose. Read what the compiler says, make the change, press Check. Nothing to install, no configuration, no blank page to stare at.
You go in order. One exercise is open at a time, and the next one is the only choice on screen.
94 exercises/free/nothing to install
Starting makes an account. It holds your place in the list, and nothing else.
How it works
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01
The exercise opens
One file, already broken, with a comment saying what it wants. No setup, no project to create, no terminal.
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02
The compiler explains
A real diagnostic, not a paraphrase: what is wrong, what kind of error it is, and where. Hints reveal one at a time if you want them.
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03
You press Check
It compiles and runs the tests for real. When it passes, the next exercise is the only thing in front of you.
What is in the course
Built on rustlings, the exercise set the Rust project itself maintains. Rust today; another language is another course.What people say about rustlings
codecrab runs the rustlings course. This is what people say about the exercises themselves, on their own pages.Who it is for
If you have never compiled anything, exercise 1 already runs, you change one line to make it say something else, and that is the whole first lesson.
If you are switching into engineering, reading a compiler error and acting on it is most of the job. This is that, 94 times, in order.
If you have started learning to code three times already, there is nothing here to choose from and no video to keep pace with. One file is open, and finishing it takes minutes.
Questions
Do I need to install anything?
No. The code compiles on a server and the output comes back to the page. Any browser works.
Do I need an account?
Yes, to run code. The exercise on this page is editable without one, but compiling happens on a server, so Check asks you to sign in first. It is free, and it is what keeps your place when you close the tab.
What if I get stuck?
Each exercise has hints that reveal one at a time, and the solution is there when you want it. Reading the solution is not a penalty.
Which language is the course?
Rust, built from the rustlings exercises. The app is not tied to it: a course is a set of exercises plus a runner, so another language is another course.
How long does it take?
Most exercises are one change. People finish the 94 over a few weeks of short sittings, and stopping mid-course costs nothing.
Exercise 1 is already broken.
It takes one line to fix.