This module defines an applicative functor for applicative validation.
Applicative validation differs from monadic validation using Either in
that it allows us to collect multiple errors using a Semigroup, whereas
Either terminates on the first error.
data V err resultThe V functor, used for applicative validation
The Applicative instance collects multiple failures in
an arbitrary Semigroup.
For example:
validate :: Person -> V [Error] Person
validate person = { first: _, last: _, email: _ }
<$> validateName person.first
<*> validateName person.last
<*> validateEmail person.emailinvalid :: forall err result. err -> V err resultFail with a validation error
runV :: forall err result r. (err -> r) -> (result -> r) -> V err result -> rUnpack the V type constructor, providing functions to handle the error
and success cases.
isValid :: forall err result r. V err result -> BooleanTest whether validation was successful or not
instance showV :: (Show err, Show result) => Show (V err result)instance functorV :: Functor (V err)instance applyV :: (Semigroup err) => Apply (V err)instance applicativeV :: (Semigroup err) => Applicative (V err)This module defines an Alternative instances for
validations that supports errors with multiple alternatives
This validation works exactly as Data.Validation
but uses Semiring instead of Semigroup
data V err resThe V functor, used for alternative validation
The Alternative instance collects multiple failures in
an arbitrary Semiring.
For example:
import Data.Semiring.Free
validate r :: Person -> V (Free Error) Person
validate person = { first: _, last: _, contact: _}
<$> validateName person.first
<*> validateName person.last
<*> (validateEmail person.contact <|> validatePhone person.contact)invalid :: forall err result. err -> V err resultFail with a validation error
runV :: forall err result r. (err -> r) -> (result -> r) -> V err result -> rUnpack the V type constructor, providing functions to handle the error
and success cases.
isValid :: forall err result. V err result -> BooleanTest whether validation was successful or not
instance showV :: (Show err, Show result) => Show (V err result)instance functorV :: Functor (V err)instance applyV :: (Semiring err) => Apply (V err)instance applicativeV :: (Semiring err) => Applicative (V err)instance altV :: (Semiring err) => Alt (V err)instance plusV :: (Semiring err) => Plus (V err)instance alernativeV :: (Semiring err) => Alternative (V err)
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