Safe Haskell | None |
---|

This module defines the `Form`

type, its instances, core manipulation functions, and a bunch of helper utilities.

- data Proved proofs a = Proved {}
- unitProved :: FormId -> Proved () ()
- type FormState m input = ReaderT (Environment m input) (StateT FormRange m)
- data Value a
- getFormInput :: Monad m => FormState m input (Value input)
- getFormInput' :: Monad m => FormId -> FormState m input (Value input)
- getFormRange :: Monad m => FormState m i FormRange
- data Environment m input
- = Environment (FormId -> m (Value input))
- | NoEnvironment

- getFormId :: Monad m => FormState m i FormId
- incFormId :: Monad m => FormState m i ()
- newtype View error v = View {}
- newtype Form m input error view proof a = Form {}
- bracketState :: Monad m => FormState m input a -> FormState m input a
- runForm :: Monad m => Environment m input -> String -> Form m input error view proof a -> m (View error view, m (Result error (Proved proof a)))
- runForm' :: Monad m => Environment m input -> String -> Form m input error view proof a -> m (view, Maybe a)
- viewForm :: Monad m => String -> Form m input error view proof a -> m view
- eitherForm :: Monad m => Environment m input -> String -> Form m input error view proof a -> m (Either view a)
- view :: Monad m => view -> Form m input error view () ()
- (++>) :: (Monad m, Monoid view) => Form m input error view () () -> Form m input error view proof a -> Form m input error view proof a
- (<++) :: (Monad m, Monoid view) => Form m input error view proof a -> Form m input error view () () -> Form m input error view proof a
- mapView :: (Monad m, Functor m) => (view -> view') -> Form m input error view proof a -> Form m input error view' proof a
- mkOk :: Monad m => FormId -> view -> a -> FormState m input (View error view, m (Result error (Proved () a)))

# Proved

Proved records a value, the location that value came from, and something that was proved about the value.

# FormState

type FormState m input = ReaderT (Environment m input) (StateT FormRange m)Source

inner state used by `Form`

.

used to represent whether a value was found in the form submission data, missing from the form submission data, or expected that the default value should be used

getFormInput :: Monad m => FormState m input (Value input)Source

Utility function: Get the current input

getFormInput' :: Monad m => FormId -> FormState m input (Value input)Source

Utility function: Gets the input of an arbitrary `FormId`

.

getFormRange :: Monad m => FormState m i FormRangeSource

Utility function: Get the current range

data Environment m input Source

The environment is where you get the actual input per form.

The `NoEnvironment`

constructor is typically used when generating a
view for a GET request, where no data has yet been submitted. This
will cause the input elements to use their supplied default values.

Note that `NoEnviroment`

is different than supplying an empty environment.

Environment (FormId -> m (Value input)) | |

NoEnvironment |

(Monoid input, Monad m) => Monoid (Environment m input) | Not quite sure when this is useful and so hard to say if the rules for combining things with Missing/Default are correct |

getFormId :: Monad m => FormState m i FormIdSource

Utility function: returns the current `FormId`

. This will only make sense
if the form is not composed

A view represents a visual representation of a form. It is composed of a function which takes a list of all errors and then produces a new view

# Form

newtype Form m input error view proof a Source

a `Form`

contains a `View`

combined with a validation function
which will attempt to extract a value from submitted form data.

It is highly parameterized, allowing it work in a wide variety of different configurations. You will likely want to make a type alias that is specific to your application to make type signatures more manageable.

`m`

- A monad which can be used by the validator
`input`

- A framework specific type for representing the raw key/value pairs from the form data
`error`

- A application specific type for error messages
`view`

- The type of data being generated for the view (HSP, Blaze Html, Heist, etc)
`proof`

- A type which names what has been proved about the return value.
`()`

means nothing has been proved. `a`

- Value return by form when it is successfully decoded, validated, etc.

This type is very similar to the `Form`

type from
`digestive-functors <= 0.2`

. If `proof`

is `()`

, then `Form`

is an
applicative functor and can be used almost exactly like
`digestive-functors <= 0.2`

.

(Monoid view, Monad m) => IndexedApplicative (Form m input error view) | |

Monad m => IndexedFunctor (Form m input view error) | |

Functor m => Functor (Form m input error view ()) | |

(Functor m, Monoid view, Monad m) => Applicative (Form m input error view ()) |

bracketState :: Monad m => FormState m input a -> FormState m input aSource

## Ways to evaluate a Form

runForm :: Monad m => Environment m input -> String -> Form m input error view proof a -> m (View error view, m (Result error (Proved proof a)))Source

Run a form

runForm' :: Monad m => Environment m input -> String -> Form m input error view proof a -> m (view, Maybe a)Source

Run a form

Just evaluate the form to a view. This usually maps to a GET request in the browser.

:: Monad m | |

=> Environment m input | Input environment |

-> String | Identifier for the form |

-> Form m input error view proof a | Form to run |

-> m (Either view a) | Result |

Evaluate a form

Returns:

`Left view`

- on failure. The
`view`

will have already been applied to the errors. `Right a`

- on success.

(++>) :: (Monad m, Monoid view) => Form m input error view () () -> Form m input error view proof a -> Form m input error view proof aSource

Append a unit form to the left. This is useful for adding labels or error fields.

The `Forms`

on the left and right hand side will share the same
`FormId`

. This is useful for elements like ```
<label
for="someid">
```

, which need to refer to the id of another
element.

(<++) :: (Monad m, Monoid view) => Form m input error view proof a -> Form m input error view () () -> Form m input error view proof aSource

Append a unit form to the right. See `++>`

.