It looks like python, so the semi-colons are unnecessary.
If you want to rid yourself of datetime for whatever reason, implement it as a list, returning name_of_day[x], so that you can start the week on a Sunday(=0) easily if you want to.
Python ships with a standard datetime class which is powerful enough to represent time, and there is a ubiquitous module, dateutil, which extends it to do nearly anything people need to do with dates regularly.
Additionally, one would normally use an array of names and index it:
I have a better one. Project manager replaced enums with strings and instead of the switch statement he put a long list of if-s (without the else-s, too), and a lot of obfuscated crap between the braces.. Guess who had to sort out that mess?
Also, the motivation for that horror was related to how those string parameters were visible in intellisense (because they were made static members in a class). Don't even ask.