title: Yesod build error because of the duplicate definition for symbol "hsprimitive_memcpy"
body: <p>I followed "Yesod quick start guide" to install Yesod in Windows 10.
  But, when I issued the <code>stack build</code> command, it failed.</p>
  
  <h3>Environment</h3>
  
  <ul>
  <li>Windows 10 (64bits)</li>
  <li><code>stack-0.1.5</code> (for Windows10 64bits)</li>
  <li>Haskell Platform 7.10.2-a (from HaskellPlatform-7.10.2-a-x86_64-setup.exe)</li>
  </ul>
  
  <h3>alex-3.1.4.log</h3>
  
  <pre><code>GHC runtime linker: fatal error: I found a duplicate definition for symbol
     hsprimitive_memcpy
  whilst processing object file
     C:\Users\xxxxx\AppData\Roaming\stack\snapshots\x86_64-windows\lts-3.8\7.10.2\lib\x86_64-windows-ghc-7.10.2\primitive-0.6.1.0-5Jnw7oEuYtM9dmKXelGXVb\HSprimitive-0.6.1.0-5Jnw7oEuYtM9dmKXelGXVb.o
  This could be caused by:
     * Loading two different object files which export the same symbol
     * Specifying the same object file twice on the GHCi command line
     * An incorrect `package.conf' entry, causing some object to be
       loaded twice.
  ghc: panic! (the 'impossible' happened)
    (GHC version 7.10.2 for x86_64-unknown-mingw32):
      loadObj "C:\\Users\\xxxxx\\AppData\\Roaming\\stack\\snapshots\\x86_64-windows\\lts-3.8\\7.10.2\\lib\\x86_64-windows-ghc-7.10.2\\primitive-0.6.1.0-5Jnw7oEuYtM9dmKXelGXVb\\HSprimitive-0.6.1.0-5Jnw7oEuYtM9dmKXelGXVb.o": failed
  </code></pre>