Data.Aeson.Lens problems

gistfile1.hs

{-# LANGUAGE OverloadedStrings #-}

import Data.Aeson.Lens
import Data.Text
import Data.Text.Encoding as E

main = do
    lex x = (E.decodeUtf8 "{\"a\": 1}") ^? key "a"

    return ()



    No instance for (AsValue Text) arising from a use of ‘key’
    In the second argument of ‘(^?)’, namely ‘key "a"’
    In the expression: (decodeUtf8 "{\"a\": 1}") ^? key "a"
    In an equation for ‘x’: x = (decodeUtf8 "{\"a\": 1}") ^? key "a"