Mathematica Notebooks have some REPL-like aspects, but they really should be uses like a script editor that shows the script output inline. You can jump between

Mathematica Notebooks have some REPL-like aspects, but they really should be uses like a script editor that shows the script output inline. You can jump between script segments and execute them out of order, which is useful in some cases. But notebooks are at their best when you have some discipline when editing, so that they stay in a state where you can open them, select execute notebook from the menu and everything works on the first try.