title: Haskell: Trouble updating/detecting cabal
body: <p>I have both ghci versions 7.10 and 8 installed on my Ubuntu 16.04. I want to install something based on cabal. I already have cabal installed as the command</p>
  
  <pre><code>cabal --version
  </code></pre>
  
  <p>yields</p>
  
  <pre><code>cabal-install version 1.22.6.0
  using version 1.22.5.0 of the Cabal library 
  </code></pre>
  
  <p>But when I go to update with</p>
  
  <pre><code>cabal update
  </code></pre>
  
  <p>I get</p>
  
  <pre><code>Downloading the latest package list from hackage.haskell.org
  cabal: does not exist
  </code></pre>
  
  <p>So I am not sure what is going on or how to resolve this. I hope to afterwards install <code>gloss</code> which is based on cabal. But</p>
  
  <pre><code>cabal install gloss-examples
  </code></pre>
  
  <p>yields</p>
  
  <pre><code>Resolving dependencies...
  Downloading bindings-DSL-1.0.23...
  Downloading bmp-1.2.6.3...
  Failed to install bmp-1.2.6.3
  Downloading vector-0.10.12.3...
  Build log ( /home/username/.cabal/logs/bmp-1.2.6.3.log ):
  cabal: /home/username/.cabal/logs/bmp-1.2.6.3.log: does not exist
  </code></pre>
  
  <p>EDIT: I originally installed ghci 7.10. Then later installed ghci 8. Could this have any effect?</p>
  
  <p>EDIT2: After installing</p>
  
  <pre><code>cabal install Cabal cabal-install
  </code></pre>
  
  <p>I still get the same error with</p>
  
  <pre><code>cabal update
  </code></pre>
  
  <p>Also I still cannot </p>
  
  <pre><code>cabal install gloss-examples
  </code></pre>
  
  <p>But I get a different error this time</p>
  
  <pre><code>Resolving dependencies...
  Downloading bindings-DSL-1.0.23...
  Downloading bmp-1.2.6.3...
  Failed to install bindings-DSL-1.0.23
  Downloading vector-0.10.12.3...
  Build log ( /home/aa/.cabal/logs/bindings-DSL-1.0.23.log ):
  cabal: /home/aa/.cabal/logs/bindings-DSL-1.0.23.log: does not exist
  </code></pre>
  
  <p>EDIT3: When I installed Cabal, it says that I installed</p>
  
  <pre><code>Installed cabal-install-1.24.0.2
  </code></pre>
  
  <p>But when I check with 
      cabal --version</p>
  
  <p>I am still stuck at </p>
  
  <pre><code>cabal-install version 1.22.6.0
  </code></pre>
  
  <p>which tells me somehow they are not linked.</p>