Visual augmentation of source code editors: A systematic review https://arxiv.org/abs/1804.02074
A useful paper categorising all the different ways IDEs can show additional metadata alongside the code.
For example, they show this cute plugin (Clepsydra) that shows worst case runtime.
Related Posts
Really cute approach to reporting type errors: when there's a type error, show an example of a runtime error that the type check has prevented!
Data-Driven Techniques for Type Error Diagnosis https://escholarship.org/uc/item/59s4h4pv
I'm trying to decide what program I should show on the home page of my PL.
Hello World is too simple to show much syntax. Fibonacci is OK but the reader may not know what print(fib(10)) should show.
Maybe print(greet("World")) is better? It gives you a function definition at least.
Over a sufficiently long time horizon, all code you write is legacy code.