I find that a blocker for me in getting started contributing to core things is finding the entry points for the code. If I want to look at “how compilation works”, I can find very complicated flow charts that explain the algorithm which are helpful in understanding it theoretically. However, I find it hard to find the literal functions in Base that get called when I execute a function for the first time. I spend a bunch of time reading source code, piecing things together, and then run out of time/energy to actually think about contributing.
I wonder if others would find it valuable to have a JuliaCon presentation that walks through “How [Complication or GC or whatever] is implemented” that doesn’t attend so much to the exact logic of the algorithm, but instead tours the code and shows where one should look for different aspects of the processes.