title: Nix and Haskell-ng install error : attribute ‘nixpkgs’ in selection path ‘nixpkgs.haskellEnv’ not found
body: <p>I am following <a href="https://iilab.org/news/2015-03-27-nix-osx-haskellng-hakyll.html" rel="noreferrer">this</a> guide to set up nix and haskell-ng. But when I get to the step </p>
  
  <blockquote>
    <p>nix-env -iA nixpkgs.haskellEnv</p>
  </blockquote>
  
  <p>then I get the error:</p>
  
  <blockquote>
    <p>error: attribute ‘nixpkgs’ in selection path ‘nixpkgs.haskellEnv’ not
    found</p>
  </blockquote>
  
  <p>Any idea what is going wrong?</p>