form-api.purs

-- A `Form` encapsulates some input of type `a`. A `Form` will likely bundle
-- up an Eq dictionary for `a` as you'll likely need to compare form values
-- for equality. It'll also bundle up a validator perhaps. Likely should be
-- an invariant functor.
data Form a

-- A `FormSet` is a mapping of labels to `Form` values.
data FormSet (fields :: # Type)

-- The initial empty `FormSet`.
formSet :: FormSet ()

-- Terminal tranformation which seals the `FormSet`, yield a Form that
-- works on records.
toForm :: forall r. FormSet r -> Form (Record r)

-- Associates a type-level label with some `Form` in a `FormSet`.
row
  :: forall sym r1 r2 a
   . IsSymbol sym
  => RowCons sym a r1 r2
  => SProxy sym
  -> Form a
  -> FormSet r1
  -> FormSet r2

-- Some simple bare-bones inputs. In a real API they might take options
-- for rendered labels, help text, etc. 
textInput  :: Form String
emailInput :: Form Email
checkInput :: Form Boolean

myForm :: Form { name :: String, email :: Email, subscribed :: Boolean }
myForm =
  formSet
    # row (SProxy :: SPoxy "name") textInput
    # row (SProxy :: SProxy "email") emailInput
    # row (SProxy :: SProxy "subscribe") checkInput
    # toForm

data FormQuery a

-- Turns a Form into a component that takes values, and yields new values.
-- Might also yield validation messages in a different Message.
toComponent :: forall m a. Form a -> H.Component H.HTML FormQuery a a m