Would like to do something like this in the parser

Parser.hs

maybeweight :: { Maybe Weight }
    : {- empty -}                       { Nothing }
    | '{-# WEIGHT' INTEGER '#-}'        { Just (Weight $ getINTEGER $2) 
    
{- Error:
compiler/stage1/build/Parser.hs:9945:34: error:
    • Couldn't match expected type ‘Integer’
                  with actual type ‘IntegralLit’
    • In the second argument of ‘($)’, namely ‘getINTEGER happy_var_2’
      In the first argument of ‘Just’, namely
        ‘(Weight $ getINTEGER happy_var_2)’
      In the first argument of ‘happyIn249’, namely
        ‘(Just (Weight $ getINTEGER happy_var_2))’
     |
9945 |                  (Just (Weight $ getINTEGER happy_var_2)
     |                                  ^^^^^^^^^^^^^^^^^^^^^^
-}