Minimal test app

Yesod/Form/Types.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeFamilies #-}
 module Yesod.Form.Types
     ( -- * Helpers
       Enctype (..)
@@ -100,7 +101,7 @@ data FieldSettings msg = FieldSettings
     , fsName :: Maybe Text
     }
 
-instance IsString a => IsString (FieldSettings a) where
+instance (a ~ Text) => IsString (FieldSettings a) where
     fromString s = FieldSettings (fromString s) Nothing Nothing Nothing
 
 data FieldView xml = FieldView

hello-forms.hs

@@ -0,0 +1,48 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes, TypeFamilies, TemplateHaskell, MultiParamTypeClasses #-}
+import Yesod.Core
+import Yesod.Form
+import Control.Applicative
+import Data.Text (Text, pack)
+import Network.Wai.Handler.Warp (run)
+
+data Fruit = Apple | Banana | Pear
+    deriving (Show, Enum, Bounded, Eq)
+
+fruits :: [(Text, Fruit)]
+fruits = map (\x -> (pack $ show x, x)) [minBound..maxBound]
+
+myForm = fixType $ runFormGet $ renderDivs $ pure (,,,,)
+    <*> areq textField "Text field" Nothing
+    <*> areq (selectField fruits) "Select field" Nothing
+    <*> aopt (selectField fruits) "Opt select field" Nothing
+    <*> aopt intField "Opt int field" Nothing
+    <*> aopt (radioField fruits) "Opt radio" Nothing
+
+data HelloForms = HelloForms
+type Handler = GHandler HelloForms HelloForms
+
+fixType :: Handler a -> Handler a
+fixType = id
+
+instance RenderMessage HelloForms FormMessage where
+    renderMessage _ _ = defaultFormMessage
+
+instance Yesod HelloForms where
+    approot _ = ""
+
+mkYesod "HelloForms" [parseRoutes|
+/ RootR GET
+|]
+
+getRootR = do
+    ((res, form), enctype) <- myForm
+    defaultLayout [whamlet|
+<p>Result: #{show res}
+<form enctype=#{enctype}>
+    ^{form}
+    <div>
+        <input type=submit>
+|]
+
+main = toWaiApp HelloForms >>= run 3000