use_python() {
  local python_root=$HOME/.pyenv/versions/$1
  load_prefix "$python_root"
  if [[ -x "$python_root/bin/python3" ]]; then
    layout python3
  else
    layout python
  fi
}

use_ruby() {
  local ruby_root=$HOME/.rubies/$1
  load_prefix "$ruby_root"
  layout_ruby
}

use_rubyinstall() {
  local ruby_version=$1
  local ruby_version_no=$(echo $ruby_version | sed -e 's/ruby-//g')
  local ruby_root=$(direnv_layout_dir)/ruby/$ruby_version
  local ruby_install=~/.rubies/$ruby_version

  if [[ ! -d $ruby_root ]]; then
    if [[ ! -d $ruby_install ]]; then
        echo "Could not find ruby version $ruby_version at $ruby_install - perhaps you need to install a ruby using ruby-install?"
        exit 1
    fi

    mkdir -p $ruby_root
#    cp -R $ruby_install $(dirname $ruby_root)
     ruby-install --no-download --install-dir $ruby_root $ruby_version
  fi

  load_prefix "$ruby_root"

  # Set the GEM_HOME to the ruby-install gem path
  export GEM_HOME=$(direnv_layout_dir)/ruby/${ruby_version}/lib/ruby/gems/${ruby_version_no}
  export BUNDLE_BIN=$(direnv_layout_dir)/ruby/${ruby_version}/bin

  PATH_add "$GEM_HOME/bin"
  PATH_add "$BUNDLE_BIN"
}