Pagination: Define page number request param name in one place

src/Vervis/Paginate.hs

@@ -25,6 +25,8 @@ import Control.Arrow (second)
 import Data.Default.Class (def)
 import Data.Maybe (fromMaybe)
 import Data.Monoid ((<>))
+import Data.Text (Text)
+import Formatting (sformat, stext, int, (%))
 import Yesod.Core (MonadHandler (HandlerSite))
 import Yesod.Core.Handler (getCurrentRoute, lookupGetParam)
 import Yesod.Core.Widget (WidgetT)
@@ -39,8 +41,11 @@ import Yesod.Paginate.Local
 navSettings :: NavSettings
 navSettings = def
 
+pageParam :: Text
+pageParam = "page"
+
 getCurrentPage :: MonadHandler m => m Int
-getCurrentPage = lookupGetParam "page" <&> \ mpage ->
+getCurrentPage = lookupGetParam pageParam <&> \ mpage ->
     case mpage of
         Nothing   -> 1
         Just page ->
@@ -72,5 +77,5 @@ navWidget nm = do
     route <-
         fromMaybe (error "Pagination in invalid response content") <$>
         getCurrentRoute
-    let url n = (route, "?page=" <> T.pack (show n))
+    let url n = (route, sformat ("?" % stext % "=" % int) pageParam n)
     pageNavWidget nm navWidgetSettings url