title: Could not find module `Data.Map' -- It is a member of the hidden package
body: <p>First, I created a new workspace:</p>
  
  <pre><code>stack new xxxx
  stack init
  stack build
  </code></pre>
  
  <p>then</p>
  
  <pre><code>cd xxx\app
  stack ghci
  import Data.Map
  </code></pre>
  
  <p>I can import other modules like <code>Data.Char</code> and <code>Data.List</code>, but I can't import <code>Data.Map</code>. GHCi told me:</p>
  
  <pre><code>Could not find module 'Data.Map'
   It is a member of the hidden package 'containers-0.5.7.1@containers-0.5.7.1'.`
  </code></pre>