Generate valid HTML from renderTable

yesod-form/Yesod/Form/Functions.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TupleSections #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
@@ -356,15 +357,21 @@ type FormRender m a =
     -> MForm m (FormResult a, WidgetT (HandlerSite m) IO ())
 
 renderTable, renderDivs, renderDivsNoLabels :: Monad m => FormRender m a
+-- | Render a form into a series of tr tags. Note that, in order to allow
+-- you to add extra rows to the table, this function does /not/ wrap up
+-- the resulting HTML in a table tag; you must do that yourself.
 renderTable aform fragment = do
     (res, views') <- aFormToForm aform
     let views = views' []
     let widget = [whamlet|
 $newline never
-\#{fragment}
-$forall view <- views
+$if null views
+    \#{fragment}
+$forall (isFirst, view) <- addIsFirst views
     <tr :fvRequired view:.required :not $ fvRequired view:.optional>
         <td>
+            $if isFirst
+                \#{fragment}
             <label for=#{fvId view}>#{fvLabel view}
             $maybe tt <- fvTooltip view
                 <div .tooltip>#{tt}
@@ -373,6 +380,9 @@ $forall view <- views
             <td .errors>#{err}
 |]
     return (res, widget)
+  where
+    addIsFirst [] = []
+    addIsFirst (x:y) = (True, x) : map (False, ) y
 
 -- | render a field inside a div
 renderDivs = renderDivsMaybeLabels True