title: GLR_Lib.hs: Could not find module 'System'
body: <p>I am trying to generate a GLR parser from happy, but I am getting errors once the files are generated.</p>
  
  <p>Here is an example, ABC.y , so it's clear what I am trying:</p>
  
  <pre><code>{
  module Main where
  }
  %name ps1 s1
  %tokentype { ABC }
  %error { parseError }
  %token
    a { A }
    b { B }
    c { C }
  %%
  
  s1: a a a b {} | b s2 a {}
  s2: b a b s2 {} | c {}
  {
  data ABC = A | B | C
  parseError _ = error "bad"
  main = getContents &gt;&gt;= print . ps1 . lexer
  lexer ('a':xs) = A : lexer xs
  ETC
  }
  </code></pre>
  
  <p>This example works just fine with </p>
  
  <pre><code>happy ABC.y
  </code></pre>
  
  <p>However, happy'd with --glr, I cannot build the result.  I am wondering if I am doing it wrong.  To be precise, happy --glr, produces the two outputs, ABC.hs. ABCData.hs, however,</p>
  
  <pre><code>ghc --make ABC.hs ABCData.hs
  </code></pre>
  
  <p>fails now.  The error I get is Could not find module 'System', It is a hidden member of haskell-98...  I tried adding package haskell98, and got ambiguous prelude problems.  I also tried coding the grammar into BNFC and using their -glr option, but I still get other errors, like dependency on Data.FiniteMap which is apparently deprecated.  Is there a way to get this compiling?  </p>