Setup CI using Github Actions (#50)

* setup a simple CI using GitHub actions

* describe a simple dev setup process

* build branches with pull requests against master, run build on multiple operating systems

* trigger CI for all branches

* always checkout the ref

* build only on pull_request events not to duplicate builds

* build only on Ubuntu

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  pull_request:
+    branches:
+        - '*'
+
+jobs:
+  stack:
+    name: ${{ matrix.os }} / stack / ghc ${{ matrix.ghc }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest]
+        stack: ["2.3.3"]
+        ghc: ["8.8.3"]
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: actions/setup-haskell@v1.1
+      name: Setup Haskell Stack
+      with:
+        enable-stack: true
+        stack-no-global: true
+        stack-setup-ghc: true
+        stack-version: ${{ matrix.stack }}
+        ghc-version: ${{ matrix.ghc }}
+
+    - uses: actions/cache@v2
+      name: Cache ~/.stack
+      with:
+        path: ~/.stack
+        key: ${{ matrix.os }}-${{ matrix.ghc }}-stack
+
+    - name: Build
+      run: |
+        stack build

README.md

@@ -1,3 +1,5 @@
+[![GitHub CI](https://github.com/saurabhnanda/odd-jobs/workflows/CI/badge.svg)](https://github.com/saurabhnanda/odd-jobs/actions)
+
 # Introduction
 
 - [Odd Jobs home page](https://www.haskelltutorials.com/odd-jobs) - contains a description of top-level features of this library
@@ -14,3 +16,16 @@ If you are already using, or considering using, `odd-jobs` in production, please
 # Contributing
 
 Please read the [contribution guidelines](./CONTRIBUTING.md)
+
+## Development
+
+### Prerequisites
+
+- [The Haskell Tool Stack](https://docs.haskellstack.org/en/stable/README/#how-to-install)
+- `libpq-dev` library (required for PostgreSQL dependency)
+
+### Build
+
+```bash
+stack build
+```