Web/Libraries/Formlets
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Revision as of 09:07, 12 August 2008 by ChrisEidhof (talk | contribs)
Introduction
Formlets are a way of building HTML forms that are type-safe, handle errors, abstract and are easy to combine into bigger forms. Here's an example:
name :: XHtmlForm String
name = input Nothing
The input function takes a Maybe String, and produces a XHtmlForm String. The Maybe String is used for default values. If you give it a nothing, it won't have a default value. If you pass in a (Just "value"), it will be pre-populated with the value "value".
You can easily combine formlets using the combinators from Applicative. Suppose you have a User-datatype:
data User = User {name :: String, age :: Integer, email :: String}
You can then build a form that produces a user:
userForm :: Form User
userForm = User <$> name <*> inputInteger <*> input Nothing