Functional programming enables local reasoning about your program: since effectful code is clearly signaled with various monads, you can be sure that some pure

Functional programming enables local reasoning about your program: since effectful code is clearly signaled with various monads, you can be sure that some pure code is such just by looking at the type. This lets me think less about the surrounding context do you understand a given block of code. So, I would say the advantage of a pure functional programming language is that it enforces and encourages writing pure code. You can still write in the style to some degree in python, but you don’t get all of the idioms language support to make functional programming really nice. I notice a difference in my code when I write in a pure language. There are some cases where you really want in place mutation— graph algorithms are good example—but for most other things, I feel like functional programming wins because of how you can think about your code, and less about code actually can or cannot do.