Rake task to compile/copy elm

Elm.rake

namespace :elm do
  Apps = [ "WorkspaceMain", "ManageSubscribersMain", "NotebookMain", "ResponsesMain" ]
  JsFileName = "irn_elm.js"
  JsOutputDir = "app/assets/javascripts"

  desc "Updates packages, compiles the Elm code and copies it to #{JsOutputDir}"
  task :compile_and_copy => [:package_install, :make, :copy] do
    puts "Updated Packages, Compiled and copied Elm code to #{JsOutputDir}"
  end

  desc "Compiles the Elm code and copies it to #{JsOutputDir}"
  task :offline_compile_and_copy => [:make, :copy] do
    puts "Compiled and copied Elm code to #{JsOutputDir}"
  end

  desc "Runs package install and elm make"
  task :compile => [:package_install, :make] do
    puts "Updated Packages and Compiled Elm code to #{JsOutputDir}"
  end

  desc "Runs elm package install"
  task :package_install do
    Dir.chdir("../elm") do
      unless system "elm package install"
        puts "Failed to run 'elm package install'"
        exit 1
      end
    end
  end

  desc "Compiles the Elm code"
  task :make do
    Dir.chdir("../elm") do
      files = Apps.map{|name| "src/#{name}.elm"}.join " "
      puts "Compiling #{files} -> #{JsFileName}"
      unless system "elm make #{files} --output #{JsFileName}"
        puts "Failed to compile elm code #{files}"
        exit 1
      end
    end
  end

  desc "Copies the compiled Elm code to #{JsOutputDir}"
  task :copy do
    Dir.chdir("../elm") do
      puts "Copying javascript #{JsFileName}"
      FileUtils.cp(JsFileName, "../rails/#{JsOutputDir}")
    end
  end
end