tcfail016.hs:8:1: error:
    • Couldn't match type ‘(t, Expr t)’ with ‘Expr t’
      Expected type: AnnExpr t -> [[Char]]
        Actual type: Expr t -> [[Char]]
    • Relevant bindings include
        g :: AnnExpr t -> [[Char]] (bound at tcfail016.hs:8:1)