compiler-error

toResponse :: IO (Response BL.ByteString) -> BL.ByteString
toResponse i = view responseBody i

-- compiler error
    Couldn't match type ‘IO (Response BL.ByteString)’
                   with ‘Response BL.ByteString’
    arising from a functional dependency between:
      constraint ‘mtl-2.2.1:Control.Monad.Reader.Class.MonadReader
                    (Response BL.ByteString) ((->) (IO (Response BL.ByteString)))’
        arising from a use of ‘view’
      instance ‘mtl-2.2.1:Control.Monad.Reader.Class.MonadReader
                  r ((->) r)’
        at <no location info>
    In the expression: view responseBody i
    In an equation for ‘imageToResponse’:
        imageToResponse i = view responseBody i
    In the expression: view responseBody i
    In an equation for ‘imageToResponse’:
        imageToResponse i = view responseBody i