I believe the only parts missing are the definitions of constants for the cost of a day and the various discounts. Perhaps also consider using the ternary operator in the discountRate function.

Correct, it shouldn't really show up in the description when you are solving in a different language... But it is quite common that you see something like "if string is empty return false (null in null-lang, 0 in 0-lang)" etc.

Haskell is a computer programming language, the comments are to exclude the Haskell implementation from certain attributes mentioned.

The DNA of a Haskell has been discovered not to be a string but a list of bases, but better research is still required.

Switch is not best practice. It looks prettier sure, but its actually slower than a simple if statement. Not by a lot though.