title: Haskell/Alex: Warning: Tab character
body: <p>I'm writing a toy language in haskell. I'm using Alex to generate a scanner. Every time I build my project with cabal, I get the following warnings:</p>
  
  <pre><code>dist/build/optimiser/optimiser-tmp/Lexer.hs:465:1: Warning:
      Tab character
  
  dist/build/optimiser/optimiser-tmp/Lexer.hs:466:1: Warning:
      Tab character
  
  dist/build/optimiser/optimiser-tmp/Lexer.hs:467:1: Warning:
      Tab character
  
  dist/build/optimiser/optimiser-tmp/Lexer.hs:471:1: Warning:
      Tab character
  
  dist/build/optimiser/optimiser-tmp/Lexer.hs:472:1: Warning:
      Tab character
  
  (plus about 10 more of these warnings)
  </code></pre>
  
  <p>It seems that the alex-generated scanner uses tabs instead of spaces, and ghc's default behaviour is to warn the user about this.</p>
  
  <p>Is anyone aware of a way to either force alex to use spaces, or to suppress those warnings from ghc (via cabal)?</p>