require $& for whitespace before or after a builder

make-pages/BuilderQQ.hs

@@ -18,9 +18,15 @@ import Data.List.NonEmpty (NonEmpty, toList)
 
 data Chunk = Lit String | Var String
 
+
+-- |
+-- * use @$var@ to insert a variable (instance of 'CanBuild')
+-- * use @$&@ to insert nothing like @\&@ in a string (e.g. to add whitespace
+--   at the start or end, or to have a variable followed by a letter
+-- * use @$$@ for a literal @$@
 parseB :: String -> ExpQ
 parseB = toExpQ . reverse . go "" [] . trim where
-  trim = dropWhileEnd isSpace . dropWhile (== '\n')
+  trim = dropWhileEnd isSpace . dropWhile isSpace
   go acc cs []             = addLit acc cs
   go acc cs ('$':'&':rest) = go acc cs rest         -- $&: expands to nothing
   go acc cs ('$':'$':rest) = go ('$' : acc) cs rest -- $$: expands to one $

make-pages/GalleryPage.hs

@@ -129,8 +129,8 @@ makeFilter prefix initial tag count = [b|
  where
   id' = [b|$prefix$&_$tag'|]
   tag' = escId tag
-  checked = if HashSet.member tag initial then [b| checked|] else ""
-  hidden = if count <= 1 then [b| hidden|] else ""
+  checked = if HashSet.member tag initial then [b|$& checked|] else ""
+  hidden = if count <= 1 then [b|$& hidden|] else ""
 
 makeYearItems :: Bool -- ^ nsfw
               -> Int -- ^ year
@@ -159,12 +159,12 @@ makeItem nsfw file info@(Info {bg}) = [b|
   title     = fromMaybe info.title $ info.galleryTitle
   dir       = takeDirectory file
   thumbnail = getThumb dir info
-  nsfw'     = if nsfw && anyNsfw info then [b| nsfw|] else ""
+  nsfw'     = if nsfw && anyNsfw info then [b|$& nsfw|] else ""
   tags'     = fold $ intersperse ";" $ map fromText $ tagsFor nsfw info
   date      = latestDateFor nsfw info
   date'     = formatTooltip date
   year'     = date.year
   updated'  = if hasUpdatesFor nsfw info then [b|true|] else [b|false|]
-  bgStyle   = case bg of Other col -> [b| style="background: $col"|]; _ -> ""
+  bgStyle   = case bg of Other col -> [b|$& style="background: $col"|]; _ -> ""
   tooltip   = [b|$title ($upd$date')|]
     where upd = if hasUpdatesFor nsfw info then "updated " else "" :: Builder

make-pages/IndexPage.hs

@@ -74,13 +74,13 @@ makeItem :: GalleryInfo -> Builder
 makeItem (GalleryInfo {title, desc, prefix, filters}) = [b|
     <li$nsfw><a href=$prefix title="$desc">$title</a></li>
   |]
-  where nsfw = if hasNsfw filters then [b| class=nsfw|] else ""
+  where nsfw = if hasNsfw filters then [b|$& class=nsfw|] else ""
 
 makeLink :: Link -> Builder
 makeLink (Link {title, url, nsfw}) = [b|
     <li$nsfw'><a href=$url>$title</a>
   |]
-  where nsfw' = if nsfw then [b| class=nsfw|] else ""
+  where nsfw' = if nsfw then [b|$& class=nsfw|] else ""
 
 hasNsfw :: GalleryFilters -> Bool
 hasNsfw (GalleryFilters {nsfw}) = nsfw /= NoNsfw

make-pages/SinglePage.hs

@@ -302,11 +302,11 @@ altButton img i = [b|
   |]
  where
   Image {label, nsfw, warning, download} = img
-  nsfwClass      = if nsfw then [b| class=nsfw|]       else ""
-  nsfwLabelClass = if nsfw then [b| class=nsfw-label|] else ""
+  nsfwClass      = if nsfw then [b|$& class=nsfw|]       else ""
+  nsfwLabelClass = if nsfw then [b|$& class=nsfw-label|] else ""
   path'          = pageFile img
   link           = fromMaybe (bigFile img) download
-  warning'       = ifJust warning \(escAttr -> w) -> [b| data-warning="$w"|]
+  warning'       = ifJust warning \(escAttr -> w) -> [b|$& data-warning="$w"|]
 
 makeTags :: FilePath -> [Strict.Text] -> Builder
 makeTags undir tags =