anchor.diff:  # VB.Net
   RUN apt-get -y install mono-vbnc
   
  -# TODO: move this up
  -# Julia
  -RUN apt-add-repository -y ppa:staticfloat/juliareleases
  -RUN apt-get -y update
  -RUN apt-get -y install julia
  -
  -# Erlang R17 (so I can use maps)
  -RUN apt-get -y install build-essential libncurses5-dev libssl-dev
  -ADD http://www.erlang.org/download/otp_src_17.5.tar.gz /tmp/
  -RUN tar -C /tmp -zxf /tmp/otp_src_17.5.tar.gz
  -RUN cd /tmp/otp_src_17.5 && ./configure && make && make install
  -RUN rm -rf /tmp/otp_src_17.5
  -# Rebar for building the Erlang implementation
  -RUN git clone -q https://github.com/rebar/rebar.git
  -RUN cd rebar && ./bootstrap && cp rebar /usr/local/bin
  -RUN rm -rf rebar
  +# TODO: move up
  +# Factor
  +RUN apt-get -y install libgtkglext1
  +RUN cd /usr/lib/x86_64-linux-gnu/ \
  +    && wget http://downloads.factorcode.org/releases/0.97/factor-linux-x86-64-0.97.tar.gz \
  +    && tar xvzf factor-linux-x86-64-0.97.tar.gz \
  +    && ln -sf /usr/lib/x86_64-linux-gnu/factor/factor /usr/bin/factor \
  +    && rm factor-linux-x86-64-0.97.tar.gz
   
   # MATLAB is proprietary/licensed. Maybe someday with Octave.
   # Swift is XCode/OS X only
  
positive.code: 
  # JavaScript
  # Already satisfied above
  
  # Lua
  RUN apt-get -y install lua5.1 lua-rex-pcre luarocks
  
negative.code: # C#
  RUN apt-get -y install mono-mcs
  
  # Erlang R17 (so I can use maps)
  RUN apt-get -y install build-essential libncurses5-dev libssl-dev
  RUN cd /tmp && wget http://www.erlang.org/download/otp_src_17.5.tar.gz \
      && tar -C /tmp -zxf /tmp/otp_src_17.5.tar.gz \
      && cd /tmp/otp_src_17.5 && ./configure && make && make install \
      && rm -rf /tmp/otp_src_17.5 /tmp/otp_src_17.5.tar.gz
  # Rebar for building the Erlang implementation
  RUN cd /tmp/ && git clone -q https://github.com/rebar/rebar.git \
      && cd /tmp/rebar && ./bootstrap && cp rebar /usr/local/bin \
      && rm -rf /tmp/rebar
  
  # Forth
  RUN apt-get -y install gforth
  
  # Go
  RUN apt-get -y install golang
  
  # Guile
  RUN apt-get -y install libunistring-dev libgc-dev autoconf libtool flex gettext texinfo libgmp-dev
  RUN git clone git://git.sv.gnu.org/guile.git /tmp/guile \
      && cd /tmp/guile && ./autogen.sh && ./configure && make && make install
  
  # Haskell
  RUN apt-get -y install ghc haskell-platform libghc-readline-dev libghc-editline-dev
  