Îõ³h$” ­)      !"#$%&'( Safe-Inferred38É×  validationThe Validate. class carries around witnesses that the type f> is isomorphic to Validation, and hence isomorphic to Either. validationAn  Validation is either a value of the type err or a , similar to ). However, the * instance for  Validation  accumulates errors using a + on err. In contrast, the  Applicative for Either returns only the first error.A consequence of this is that  Validation has no  or Ò instance. This is because such an instance would violate the law that a Monad's  must equal the  Applicative's ,)An example of typical usage can be found  Ähttps://github.com/qfpl/validation/blob/master/examples/src/Email.hshere. validations an a1 producing an updated optional value, returning e in the empty case.7This can be thought of as having the less general type: 7validate :: e -> (a -> Maybe b) -> a -> Validation e b  validation is   specialised to -2 lists, since they are a common semigroup to use. validationConverts from ) to .  validation  is useful for converting an ) to an  when the Left of the ) needs to be lifted into a +.  validation  is the catamorphism for  Validation.  validationConverts from  to ).  validationv   a returns a when v is Failure, and the a in  Success a.7This can be thought of as having the less general type: #orElse :: Validation e a -> a -> a  validation Return the a$ or run the given function over the e.7This can be thought of as having the less general type: +valueOr :: (e -> a) -> Validation e a -> a  validation# gets the value out of either side. validationŠ ensures that a validation remains unchanged upon failure, updating a successful validation with an optional value that could fail with e otherwise.7This can be thought of as having the less general type: Âensure :: e -> (a -> Maybe b) -> Validation e a -> Validation e b  validationìRun a function on anything with a Validate instance (usually Either) as if it were a function on Validation)This can be thought of as having the type Â(Either e a -> Either e' a') -> Validation e a -> Validation e' a' validationbindValidation› binds through an Validation, which is useful for composing Validations sequentially. Note that despite having a bind function of the correct type, Validation is not a monad. The reason is, this bind does not accumulate errors, so it does not agree with the Applicative instance.ÐThere is nothing wrong with using this function, it just does not make a valid Monad instance. validationThis prism generalises (. It targets the failure case of either ) or . validationThis prism generalises  (. It targets the success case of either ) or . validation' converts between any two instances of . validationNonEmpty