haskell堆栈构建与mongodb作为依赖性错误

Question

我正在尝试使用stack构建一个测试项目：

我跑了：

stack new test simple

然后我将Main.hs文件修改为：

module Main where

import Database.MongoDB as M

main :: IO ()
main = do
putStrLn "hello world"

test.cabal文件为：

executable test
hs-source-dirs:      src
main-is:             Main.hs
default-language:    Haskell2010
build-depends:       base >= 4.7 && < 5
                    ,mongodb

stack.yaml文件为：

resolver: lts-8.5
packages:
 - '.'
extra-deps:
 - mongodb-2.1.1.1

当我运行“堆栈构建”时，它显示以下错误消息：

Warning: Some extra-deps are neither installed nor in the index:
* mongodb-2.1.1.1
Didn't see mongodb-2.1.1.1 in your package indices.
Updating and trying again.
Fetched package index.                                                                                    
The following package identifiers were not found in your indices: mongodb-2.1.1.1

我已经检查过我使用lts-8.5快照安装了mongodb-2.1.1.1。

我哪里做错了？