Text.Digestive.Transform

Optionally failing transformers for forms

Documentation

newtype Transformer m e a b

A transformer that transforms a value of type a to a value of type b

Constructors

Transformer

Fields

unTransformer :: a -> m (Either [e] b)

Instances

Monad m => Arrow (Transformer m e)

Monad m => Category (Transformer m e)

transform :: Monad m => Form m i e v a -> Transformer m e a b -> Form m i e v b

Apply a transformer to a form

transformFormlet

Arguments

:: Monad m

=> (b -> a)

Needed to produce defaults

-> Formlet m i e v a

Formlet to transform

-> Transformer m e a b

Transformer

-> Formlet m i e v b

Resulting formlet

Apply a transformer to a formlet

transformEither :: Monad m => (a -> Either e b) -> Transformer m e a b

Build a transformer from a simple function that returns an Either result.

transformEitherM :: Monad m => (a -> m (Either e b)) -> Transformer m e a b

A monadic version of transformEither

transformRead

Arguments

:: (Monad m, Read a)

=> e

Error given if read fails

-> Transformer m e String a

Resulting transformer

Create a transformer for any value of type a that is an instance of Read

required

Arguments

:: Monad m

=> e

error to return if value is Nothing

-> Transformer m e (Maybe a) a

A transformer that converts 'Maybe a' to a.