在Haskell Yesod应用程序中使用Postgres数据库的问题

Question

我试图在c9工作区中的Yesod应用程序上使用Heroku Postgres数据库，但是当堆栈构建命令运行时会出现以下错误消息：

 $ stack build
    projeto-0.0.0: build (lib + exe)
    Preprocessing library projeto-0.0.0...
    [ 9 of 15] Compiling Handler.Cliente  ( src/Handler/Cliente.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/Handler/Cliente.o )

    /home/ubuntu/workspace/projeto/src/Handler/Cliente.hs:11:1: error:
        Failed to load interface for ‘Database.Persist.Postgresql’
        Use -v to see a list of the files searched for.

    --  While building package projeto-0.0.0 using:
          /home/ubuntu/.stack/setup-exe-cache/x86_64-linux/Cabal-simple_mPHDZzAJ_1.24.2.0_ghc-8.0.2 --builddir=.stack-work/dist/x86_64-linux/Cabal-1.24.2.0 build lib:projeto exe:projeto --ghc-options " -ddump-hi -ddump-to-file"
        Process exited with code: ExitFailure 1

我应该做什么？