e (Maybe B.ByteString) -- ^ Header value
getHeader n = do
    hs ← headerList
    case filter (\(Header k _) → k ≡ n) hs of
        (Header _ v:xs) → return $ Just v
        _ → return Nothing

-- | Set response header
header ∷ B.ByteString -- ^ Header name
       → B.ByteString -- ^ Heade
getHeader ∷ B.ByteString -- ^ Header name
          → Route (Maybe B.ByteString)
getHeader n = do
    hs ← headerList
    case filter (\(Header k _) → k ≡ n) hs of
        (Header _ v:xs) → return $ Just v
        _ → return Nothing

-- | Set response header
getHeader n = do
    hs ← headerList
    case filter (\(Header k _) → k ≡ n) hs of
        (Header _ v:xs) → return $ Just v
        _ → return Nothing

-- | Set response header