haskell - OverloadedLists 拡張機能が機能しない

Question

GHC 7.8 の OverloadedLists 言語プラグマは非常に魅力的であるため、試してみることにしました。

{-# LANGUAGE OverloadedLists #-}

import Data.Set (Set)                                                                     
import qualified Data.Set as Set

mySet :: Set Int
mySet = [1,2,3]

そして、コンパイラは私に与えます：

    No instance for (GHC.Exts.IsList (Set Int))
      arising from an overloaded list
    In the expression: [1, 2, 3]
    In an equation for ‘mySet’: mySet = [1, 2, 3]

    No instance for (Num (GHC.Exts.Item (Set Int)))
      arising from the literal ‘1’
    In the expression: 1
    In the expression: [1, 2, 3]
    In an equation for ‘mySet’: mySet = [1, 2, 3]
Failed, modules loaded: none.

リリース ノートの例でさえ機能しません。

> ['0' .. '9'] :: Set Char

<interactive>:5:1:
    Couldn't match type ‘GHC.Exts.Item (Set Char)’ with ‘Char’
    Expected type: [Char] -> Set Char
      Actual type: [GHC.Exts.Item (Set Char)] -> Set Char
    In the expression: ['0' .. '9'] :: Set Char
    In an equation for ‘it’: it = ['0' .. '9'] :: Set Char

ここで何が起こっているか知っている人はいますか？