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import Data.Semigroup | |
import Data.Functor | |
import Control.Applicative | |
data Validation err a = Failure err | Success a | |
deriving Show | |
instance Functor (Validation err) where | |
fmap f (Success a) = Success (f a) | |
fmap _ (Failure e) = Failure e | |
instance Semigroup err => Applicative (Validation err) where | |
pure = Success | |
Success f <*> Success a = Success (f a) | |
Success _ <*> Failure e = Failure e | |
Failure e <*> Success _ = Failure e | |
Failure e <*> Failure e' = Failure (e <> e') | |
instance Foldable (Validation err) where | |
foldr f x (Success a) = f a x | |
foldr _ x (Failure _) = x | |
instance Traversable (Validation err) where | |
traverse f (Success a) = Success <$> f a | |
traverse _ (Failure e) = pure (Failure e) | |
data Form = Form { | |
email :: String | |
, password :: String | |
} deriving Show | |
data Error = | |
EmptyField | |
| NotMinLength | |
deriving Show | |
newtype Email = Email String | |
deriving Show | |
newtype Password = Password String | |
deriving Show | |
data ValidatedForm = ValidatedForm Email Password | |
deriving Show | |
type FormValidation = Validation [Error] | |
notEmpty :: String -> FormValidation String | |
notEmpty "" = Failure [EmptyField] | |
notEmpty str = Success str | |
minLength :: String -> Int -> FormValidation String | |
minLength str n | |
| length str >= n = Success str | |
| otherwise = Failure [NotMinLength] | |
minPasswordLength :: Int | |
minPasswordLength = 8 | |
validateEmail :: String -> FormValidation Email | |
validateEmail input = | |
notEmpty input $> | |
Email input | |
validatePassword :: String -> FormValidation Password | |
validatePassword input = | |
notEmpty input *> | |
minLength input minPasswordLength $> | |
Password input | |
validateForm :: Form -> FormValidation ValidatedForm | |
validateForm (Form email password) = | |
ValidatedForm <$> | |
validateEmail email <*> | |
validatePassword password | |
mkForm :: String -> String -> FormValidation ValidatedForm | |
mkForm email password = validateForm $ Form email password |
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