foldr package:snap-core

Right fold over all key-value pairs in the headers map. Example:

ghci> :set -XOverloadedStrings
ghci> import Data.Monoid
ghci> let hdrs = H.fromList [("Accept", "text/plain"), ("Accept", "text/html")]
ghci> let f _ val (cntr, acc) = (cntr+1, val <> ";" <> acc)
ghci> H.foldr f (0, "") hdrs
(2,"text/plain;text/html;")

Same as foldr, but the key parameter is of type ByteString instead of CI ByteString. The key is case-folded (lowercase).