In Data.Password.Scrypt:

data Scrypt Phantom type for Argon2 

Should be "Phantom type for scrypt"

In Data.Password.Bcrypt's introduction:
..., it is also been...
Should be "..., it has also been..."

In Data.Password.PBKDF2's introduction:
The main reason for this is that is doesn't make...
Should be "The main reason for this is that it doesn't make..."

It is still, however used...
Should be "It is still, however, used..."