- Nothing -> ("class", "imageFrame")
- Just "left" -> ("class", "imageFrame leftFloat")
- Just "right" -> ("class", "imageFrame rightFloat")
- Just others -> error ("unknown \"float\" attribute: " ++ others)
+ Nothing → ("class", "imageFrame")
+ Just "left" → ("class", "imageFrame leftFloat")
+ Just "right" → ("class", "imageFrame rightFloat")
+ Just others → error ("unknown \"float\" attribute: " ⊕ T.unpack others)