I want to keep the code I write for historic purposes, and I would like to learn how to write tests.
Following this discussion I wrote the test as follows:

However I get an errors:
on line 8,

lsIO 
• Couldn't match type: IO String
                 with: [Char]

and on line 12,

withResource acquire tests
• Couldn't match expected type ‘TestTree’
              with actual type ‘(IO [String] -> TestTree) -> TestTree’
• Probable cause: ‘withResource’ is applied to too few arguments 

https://adventofcode.com/2023/day/1

some of the digits are actually spelled out with letters: one, two, three, four, five, six, seven, eight, and nine also count as valid "digits".

debug:

• integrate quickcheck and use PBT to find other inputs that are problematic
• use debugger to investigate the fynction step by step
• use regex to solve this problem