Custom function in Esqueleto "where_" cluase

Question

I'd like to write a function that checks if user's login and hashed password exists in database. Let's assume DB is very simple:

share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persistLowerCase|
    User
        login String
        passHash Hash
        UniqueL login
        deriving Eq Show

Where Hash is an alias type Hash = PasswordHash PBKDF2 from https://hackage.haskell.org/package/password-2.0.1.1/docs/Data-Password-PBKDF2.html.

Also, for simplicity let's assume that both login and password are passed to my function as String.

There's a function in the module called checkPassword (https://hackage.haskell.org/package/password-2.0.1.1/docs/Data-Password-PBKDF2.html#g:3) that checks if a password produces the required hash. However, I don't know how can I use it in esqualeto where_ clause.

I came up with something like this:

type DB m a = ReaderT SqlBackend m a

checkCredentials ::(MonadIO m, MonadLogger m) => (String, String) -> DB m Bool
checkCredentials (login, password) = do
    let hashFunc = (checkPassword $ mkPassword (pack password))
    res <- 
        select $ 
            from $ \user -> do 
                -- This won't wwork
                where_ (user ^. UserLogin ==. val login &&. hashFunc (user ^. UserPassHash) ==. val PasswordCheckSuccess)
                return user
    return (negate $ null res)

but the part hashFunc (user ^. UserPassHash) obviously won't work. I guess I need to enter with my hashFunc into a monad (or two), but I have no idea how to do this.

I noticed that UserPassHash is of type EntityField User Hash. I wonder how can I turn it into EntityField User PasswordCheck.