Merge IOHK fork #135

	# modified from https://github.com/jgm/pandoc/blob/master/.github/workflows/ci.yml
	name: Haskell library and example

	on:
	push:
	branches:
	- '**'
	paths-ignore: []
	pull_request:
	paths-ignore: []

	jobs:
	linux:

	runs-on: ubuntu-20.04
	strategy:
	fail-fast: false
	matrix:
	versions:
	- ghc: '8.6.5'
	cabal: '3.6'
	- ghc: '8.8.4'
	cabal: '3.6'
	- ghc: '8.10.4'
	cabal: '3.6'
	- ghc: '9.0.2'
	cabal: '3.6'
	- ghc: '9.2.4'
	cabal: '3.6'
	steps:
	- uses: actions/checkout@v2

	# need to install older cabal/ghc versions from ppa repository

	- name: Install recent cabal/ghc
	uses: haskell/actions/setup@v1
	with:
	ghc-version: ${{ matrix.versions.ghc }}
	cabal-version: ${{ matrix.versions.cabal }}

	# declare/restore cached things
	# caching doesn't work for scheduled runs yet
	# https://github.com/actions/cache/issues/63

	- name: Cache cabal global package db
	id: cabal-global
	uses: actions/cache@v2
	with:
	path: \|
	~/.cabal
	key: ${{ runner.os }}-${{ matrix.versions.ghc }}-${{ matrix.versions.cabal }}-cabal-global-${{ hashFiles('cabal.project') }}

	- name: Cache cabal work
	id: cabal-local
	uses: actions/cache@v2
	with:
	path: \|
	dist-newstyle
	key: ${{ runner.os }}-${{ matrix.versions.ghc }}-${{ matrix.versions.cabal }}-cabal-local

	- name: Install dependencies
	run: \|
	cabal update
	cabal build all --dependencies-only --enable-tests --disable-optimization
	- name: Build
	run: \|
	cabal build all --enable-tests --disable-optimization 2>&1 \| tee build.log
	- name: Test
	run: \|
	cabal test all --disable-optimization

Provide feedback