toast.yml

image: ubuntu:18.04
default: build
tasks:
  prepare_system:
    description: Install system packages and set up a non-root user.
    command: |
      set -euo pipefail

      # Create a non-root user.
      adduser --disabled-password --gecos '' user

      # Set up a directory for the non-root user's executables.
      mkdir -p /home/user/.local/bin
      chown user /home/user/.local/bin
      echo 'export PATH="/home/user/.local/bin:$PATH"' >> /home/user/.profile

      # Install system packages.
      apt-get update
      apt-get install --yes build-essential curl ruby

      # Without this, Ruby will assume files are encoded as ASCII.
      echo 'export LANG="C.UTF-8"' >> /home/user/.profile

      # Install Stack.
      curl -sSL https://get.haskellstack.org/ | sh

  install_tools:
    description: Install the tools needed to build, test, lint, and format Haskell programs.
    dependencies:
      - prepare_system
    user: user
    command: |
      set -euo pipefail

      # Download a resolver and set up the Stack user configuration.
      stack --resolver lts-12.14 setup

      # Tell Stack to install other executables in `$HOME/.local/bin`.
      echo 'local-bin-path: /home/user/.local/bin' >> \
        /home/user/.stack/config.yaml

      # Install a formatter and linter.
      stack install hindent hlint

  fetch_dependencies:
    description: Download and compile dependencies.
    dependencies:
      - install_tools
    input_paths:
      - package.yaml
      - stack.yaml
      - stack.yaml.lock
    user: user
    command: |
      set -euo pipefail

      # Set up an empty project to build just to cache the dependencies for the real codebase.
      touch README.md
      mkdir app src test
      echo 'module Main (main) where main :: IO (); main = pure ()' > \
        app/Main.hs
      echo 'main :: IO (); main = pure ()' > \
        test/Spec.hs
      stack --allow-different-user build
      stack --allow-different-user test

      # Remove build artifacts for the empty project. This will force Stack/GHC to rebuild the
      # project, which is a workaround for an issue in which Stack/GHC does not detect when source
      # files are changed.
      stack --allow-different-user clean

  build:
    description: Build the program.
    dependencies:
      - fetch_dependencies
    input_paths:
      - app
      - src
    user: user
    command: |
      set -euo pipefail

      # Build the program.
      stack --allow-different-user build

  run:
    description: Run the program.
    dependencies:
      - build
    user: user
    command: |
      set -euo pipefail

      # Run the program.
      stack --allow-different-user exec effects-exe

  test:
    description: Run the test suite.
    dependencies:
      - build
    input_paths:
      - test
    user: user
    command: |
      set -euo pipefail

      # Run the test suite.
      stack --allow-different-user test

  lint:
    description: Lint the code.
    dependencies:
      - fetch_dependencies
    input_paths:
      - app
      - scripts
      - src
      - test
      - toast.yml
    user: user
    command: |
      set -euo pipefail

      # Make sure (a) `$PATH` contains `/home/user/.local/bin` and (b) the `LANG` environment
      # variable is set for Ruby.
      source ~/.profile

      # Run the Haskell linter.
      hlint .

      # Run the general linter.
      ./scripts/lint-general.rb $(
        find . -type d \( \
          -path ./.git -o \
          -path ./.stack-work \
        \) -prune -o \( \
          -name '*.hs' -o \
          -name '*.rb' -o \
          -name '*.sh' -o \
          -name '*.yml' -o \
          -name 'Dockerfile' -o \
          -name 'Makefile' \
        \) -print
      )

      # Check that the code is correctly formatted.
      for file in $(
        find . -type d \( \
          -path ./.git -o \
          -path ./.stack-work \
        \) -prune -o \( \
          -name '*.hs' \
        \) -print \
      ); do
        cat "$file" | hindent > "$file.tmp"
        (cmp "$file.tmp" "$file" && rm "$file.tmp") ||
          (rm "$file.tmp" && false) || exit 1
      done

  format:
    description: Format the code.
    dependencies:
      - fetch_dependencies
    input_paths:
      - app
      - src
      - test
    output_paths:
      - app
      - src
      - test
    user: user
    command: |
      set -euo pipefail

      # Make sure `$PATH` contains `/home/user/.local/bin`.
      source ~/.profile

      # Format the code.
      for file in $(
        find . -type d \( \
          -path ./.git -o \
          -path ./.stack-work \
        \) -prune -o \( \
          -name '*.hs' \
        \) -print \
      ); do
        cat "$file" | hindent > "$file.tmp"
        (cmp --quiet "$file.tmp" "$file" && rm "$file.tmp") ||
          mv "$file.tmp" "$file"
      done