Some ruby-based tooling for haskell projects that makes development easier for me. Sandboxing requires cabal >= 0.1.7

Gemfile

source "http://rubygems.org"

gem "guard-shell"
gem "rake"

Guardfile

guard :shell, :all_after_pass => true do
  watch(%r{.*\.cabal$}) do
    run_all_tests
  end

  watch(%r{test/SpecHelper.hs$}) do
    run_all_tests
  end

  def run_all_tests
    ncmd("cabal configure && cabal build && cabal test")
  end

  def ncmd(cmd, msg = cmd)
    output = `#{cmd}`
    puts output
    summary = output.lines.grep(/examples/).first

    if $?.success?
      n "Build Success!", summary
    else
      n "Failed", summary
    end
  end
 
  def run_tests(mod)
    specfile = "test/#{mod}Spec.hs"
    if File.exists?(specfile)
      files = [specfile]
    else
      files = Dir['test/**/*.hs']
    end

    if package_db = Dir[".cabal-sandbox/*packages.conf.d", "cabal-dev/*packages.conf.d"].first
      package_db_flag = "-package-db #{package_db}"
    end

    ncmd("ghc -isrc -itest #{package_db_flag} -e 'Test.Hspec.hspec spec' #{files.join(' ')}")
  end

  # can we join these? why does run all loop through each file?
  watch(%r{src/(.+)\.hs$}) do |m|
    run_tests(m[1])
  end
 
  watch(%r{test/(.+)Spec\.hs$}) do |m|
    run_tests(m[1])
  end
end

Rakefile

#!/usr/bin/env rake

def number_of_cores
  `nproc`.chomp
end

def build_flags
  "-j#{number_of_cores}"
end

desc "run ghci scoped to the sandboxed cabal project"
task :ghci => FileList.new(".cabal-sandbox/*packages.conf.d", "cabal-dev/*packages.conf.d") do |x|
  cmd = "ghci -isrc"
  if package_db = x.prerequisites.first
    cmd += " -package-db #{package_db}"
  end

  sh cmd
end

desc "sandbox with cabal (requires cabal >= 0.17)"
task :sandbox do
  sh "cabal sandbox init"
end

desc "install only essential dependencies. build does this for you"
task :install_dependencies do
  sh "cabal install #{build_flags} --only-dependencies"
end

desc "install only essential dependencies. test does this for you"
task :install_dependencies_for_test do
  sh "cabal install #{build_flags} --only-dependencies --enable-tests"
end

desc "just build the project for production"
task :build => [:configure, :install_dependencies] do
  sh "cabal build #{build_flags}"
end

desc "run tests once. consider using guard afterwards for faster feedback"
task :test => :build_for_test do
  sh "cabal test"
end

desc "clean all artifacts generated by cabal"
task :clean do
  sh "cabal clean"
end

task :configure do
  sh "cabal configure"
end

task :build_for_test => [:configure, :install_dependencies_for_test] do
  sh "cabal build #{build_flags}"
end

task :default => :build