Non type-variable argument in the constraint: IArray a Int

Data.Array.Unboxedの配列を関数を使って変換処理をしたい

Data.Array.Unboxedの配列を関数を使って変換処理をしたいです。

配列の値が１ならａ、２ならｂのように変換したい。
下記プログラムではｅと表示させたい。

ですが、関数で実行させようとすると下記のようにコンパイルエラーとなります。

発生している問題・エラーメッセージ

[apo@arch my-project]$ stack build
my-project> build (lib + exe)
Preprocessing library for my-project-0.1.0.0..
Building library for my-project-0.1.0.0..
Preprocessing executable 'my-project-exe' for my-project-0.1.0.0..
Building executable 'my-project-exe' for my-project-0.1.0.0..
[1 of 2] Compiling Main

/home/apo/doc/project/make/haskell/20220730_2/my-project/app/Main.hs:8:1: error:
    ~ Non type-variable argument in the constraint: IArray a Int
      (Use FlexibleContexts to permit this)
    ~ When checking the inferred type
        func1 :: forall {a :: * -> * -> *} {i}.
                 (IArray a Int, Ix i, Num i) =>
                 a i Int -> IO ()
  |
8 | func1 xs = do
  | ^^^^^^^^^^^^^...

--  While building package my-project-0.1.0.0 (scroll up to its section to see the error) using:
      /home/apo/.stack/setup-exe-cache/x86_64-linux-tinfo6/Cabal-simple_mPHDZzAJ_3.4.1.0_ghc-9.0.2 --builddir=.stack-work/dist/x86_64-linux-tinfo6/Cabal-3.4.1.0 build lib:my-project exe:my-project-exe --ghc-options " -fdiagnostics-color=always"
    Process exited with code: ExitFailure 1

該当のソースコード

Haskell
1module Main where
2
3import Data.Array.Unboxed
4
5data0 :: UArray Int Int
6data0 = Data.Array.Unboxed.array (0,3)[(0,8),(1,4),(2,6),(3,2)]
7
8func1 xs = do
9    let t = ["a","b","c","d","e","f","g","h","i","j"]
10
11    let a = t !! (xs ! 1)
12    putStrLn(a)
13
14main :: IO ()
15main = do
16
17    putStrLn(show data0)
18    func1 data0