How to save a list to a file and read it as a list type?

You can use the pickle module for that.
This module has two methods,

1. Pickling(dump): Convert Python objects into a string representation.
2. Unpickling(load): Retrieving original objects from a stored string representation.

https://docs.python.org/3.3/library/pickle.html

Code:

>>> import pickle
>>> l = [1,2,3,4]
>>> with open("test", "wb") as fp:   #Pickling
...   pickle.dump(l, fp)
... 
>>> with open("test", "rb") as fp:   # Unpickling
...   b = pickle.load(fp)
... 
>>> b
[1, 2, 3, 4]

---

Also Json

1. dump/dumps: Serialize
2. load/loads: Deserialize

https://docs.python.org/3/library/json.html

Code:

>>> import json
>>> with open("test", "w") as fp:
...     json.dump(l, fp)
...
>>> with open("test", "r") as fp:
...     b = json.load(fp)
...
>>> b
[1, 2, 3, 4]