anchor.diff:  
   ## Command-line tools
   WORKDIR $STACK_WORKDIR
  -RUN $STACK setup; 
  +RUN $STACK setup;
   RUN $STACK install \
       pandoc \
       stylish-haskell \
  
positive.code: 
  ENV LTS_VERSION lts-5.5
  
  ## Basic dependencies 
  RUN yum install git gcc gcc-c++ gmp-devel zlib-devel libstdc++-devel -y
  
  ## Fetch and install stack
  
negative.code: 
  ## Haskell environment
  ENV PATH $HOME/local/.bin:$PATH
  ENV STACK stack --no-terminal
  ENV STACK_WORKDIR /opt/stack
  
  ## Copy across stack.yaml
  