I am learning Python and recently I have noticed that sometimes variables, function parameters and outputs are types annotated. Python is the dynamically typed language, so why should we use this feature that resembles statically typed languages?
You are right, Python is a dynamically typed language and it is its strength. This makes Python very flexible and versatile. But sometimes it becomes its weakness. There are many situations where you want to emphasize that the given variable is intended to be an integer (or string, or another type, etc). This helps in code maintenance, refactoring and debugging. Also, this makes the life of your coworkers a little bit easier.
I just want to add that some IDEs (for example, PyCharm) helps you to write clean and understandable code. In the same time, they can be wrong when showing you some tips about variables types, or function parameters and return object types. But when you explicitly specify types, this feature of IDE works significantly better.
Interesting... When this PyCharm's functionality could be useful?
For instance, you annotate the function so that it should return an integer. Then you write a lot of code and call this function. But it returns a string. PyCharm can detect this and notify you about the possible issue even before you run this code.
Thank you, now it becomes more clear for me.
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