Some Problems in Chapter 14

[pdcxs]

I follow the codes in chapter 14 and find some little problems.

1. charClass_wordy defined but not used, I think maybe the charClass function should be modified as following:

charClass (']':cs) = (']':) <$> globToRegex' cs
charClass (c:cs) = (c:) <$> charClass_wordy cs

2. According to monad fail, from GHC 8.8+, the fail function will not be supported. I suggest change the fail function to error or other implementation.

3. charClass_wordy also lacks a matching form, which should be added as follows:

charClassWordy "" = 
    error "No more input"