I don't understand how this is different from Hackerrank/Leetcode or how it's similar to Duolingo. Can someone explain what the innovation is here over HackerRank or LeetCode?
The claim of similarity to Duolingo seems to be based on the "Practice" tab, which let's you re-solve problems you've already solved once. Duolingo and similar apps use spaced repetition[1] to reinforce lessons which is proven to help retain them permanently in long term memory. However Edabit doesn't seem to implement a very complete system so it probably won't be particularly effective. I also doubt space repetition is helpful for learning to program outside of memorizing APIs and standard libraries, which is 10% of programming at most.
As for sites like Leetcode, those are far more mature (wide selection of languages, custom test cases, etc.) with much more interesting challenges. I appears Edabit is targeting beginners and therefore has much shorter, easier challenges which mainly test memory, not knowledge of algorithms or problem solving. Again, not necessarily the aspect of programming that I would encourage beginners to spend their time on compared to understanding basic concepts.
