I often work on very small pieces of code, on the order of max 100 lines, especially in scenarios when I learn something new and just play with the code, or when I debug.
Because I frequently change code and want to see how that changes the contents of my variables and output, it is tedious to either
1) hit the debug button, wait for the debugger to start (in my case I use PyCharm as an IDE) and then inspect the output
or
2) insert some prints for the variables that I want to observe and compile the code (slightly faster than starting the debugger).
To eliminate this time consuming workflow, where I constantly hit the compile or debug button every few seconds, is there an IDE where I can set a watch to a few variables and then each time I change in my source code a single character (or, alternatively, every half a second) the IDE automatically compiles everything and I will see then new values of my variables?
(Of course while I intermediatelychange the code the compilation will give errors, but that is ok. This feature would be a big time saver. Maybe PyCharm has it already implemented? If not, ideally I would hope for a language agnostic IDE, similar to PyCharm, where variants for Java etc. also exist. If not, since I code in Python, a Python IDE would also be great.)
This might not be exactly what you are looking for but PyCharm (and IntelliJ and probably others) can run tests automatically when code changes.
In the PyCharm Run toolbar look for "Toggle auto-test" button.
For example in PyCharm you can create test cases that just runs the code you're interested in and prints the variables you need. Then create a run configuration that runs only those tests and set it to run automatically.
For more details see PyCharm documentation on rerunning tests.