Orphan instances

This instance allows a Password to be created from a JSON blob.

>>> let maybePassword = decode "\"foobar\"" :: Maybe Password
>>> fmap unsafeShowPassword maybePassword
Just "foobar"

There is no instance for ToJSON for Password because we don't want to accidentally encode a plain-text Password to JSON and send it to the end-user.

Similarly, there is no ToJSON and FromJSON instance for PasswordHash because we don't want to accidentally send the password hash to the end user.

Type error! Do not use toJSON on a Password!

This instance allows a Password to be created with functions like parseUrlPiece or parseQueryParam.

>>> let eitherPassword = parseUrlPiece "foobar"
>>> fmap unsafeShowPassword eitherPassword
Right "foobar"

Type error! Do not transmit plain-text Passwords over HTTP!

Type error! Do not store plain-text Passwords in your database!

This instance allows a PasswordHash to be stored as a field in a database using Database.Persist.

>>> let salt = Salt "abcdefghijklmnop"
>>> let pass = mkPassword "foobar"
>>> let hashedPassword = hashPasswordWithSalt 10 salt pass
>>> toPersistValue hashedPassword
PersistText "$2b$10$WUHhXETkX0fnYkrqZU3ta.N8Utt4U77kW4RVbchzgvBvBBEEdCD/u"

In the example above, the long PersistText will be the value you store in the database.

We don't provide an instance of PersistField for Password, because we don't want to make it easy to store a plain-text password in the database.

This instance allows a PasswordHash to be stored as a field in an SQL database in Database.Persist.Sql.