suffices のコード例を，多少非自明なものに変更する #20

	# see: https://github.com/rami3l/plfl/blob/master/.github/workflows/ci.yml

	name: Test

	# https://docs.github.com/en/actions/using-jobs/using-concurrency#example-only-cancel-in-progress-jobs-or-runs-for-the-current-workflow
	concurrency:
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: true

	on:
	pull_request:
	push:
	branches:
	- main

	jobs:
	build:
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v3

	- name: Install elan
	run: \|
	curl https://raw.githubusercontent.com/leanprover/elan/master/elan-init.sh -sSf \| sh -s -- -y --default-toolchain $(cat lean-toolchain)
	echo "$HOME/.elan/bin" >> $GITHUB_PATH

	# src: https://harry.garrood.me/blog/easy-incremental-haskell-ci-builds-with-ghc-9.4/
	- name: Cache dependencies
	uses: actions/cache@v3
	with:
	path: \|
	./lake-packages
	key: deps-${{ runner.os }}-${{ hashFiles('lean-toolchain') }}-${{ hashFiles('lake-manifest.json') }}
	restore-keys: \|
	deps-${{ runner.os }}-${{ hashFiles('lean-toolchain') }}

	- name: Cache build
	uses: actions/cache@v3
	with:
	path: \|
	./build
	key: build-${{ runner.os }}-${{ hashFiles('lean-toolchain') }}-${{ github.sha }}
	restore-keys: \|
	build-${{ runner.os }}-${{ hashFiles('lean-toolchain') }}

	- name: Test native build
	run: \|
	lake exe cache get
	lake build

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