I used java classloader as a canonical example. In general, compilers outputs object code during development and the runtime doesn't expect syntax errors. Comp

I used java classloader as a canonical example. In general, compilers outputs object code during development and the runtime doesn't expect syntax errors. Compiler like JIT are meant for runtime optimization and not to handle the development workflow like syntax parsing. That's why errors in development workflow compilers (like JSP compiler) are incomprehensible, when you start writing code inside it. On the other hand, dynamic language interpreters already handle both syntax parsing and execution at runtime. Therefore loading changes during development is not a big deal for them.