add CI

.github/workflows/ci.yml

@@ -0,0 +1,49 @@
+name: Continuous Integration
+
+on:
+  - push:
+    branches:
+      - main
+  - pull_request
+  - workflow_dispatch
+
+jobs:
+  ci:
+    runs-on: ubuntu-20.04
+    name: Erlang ${{matrix.otp}} / rebar ${{matrix.rebar3}}
+    strategy:
+      matrix:
+        otp: ['25', '26', '27']
+        rebar3: ['3']
+        # latest rebar3 versions that do not give problems with selected OTPs
+        include:
+          - otp: '23'
+            rebar3: '3.20.0'
+          - otp: '24'
+            rebar3: '3.23.0'
+    steps:
+
+      - uses: actions/checkout@v2
+
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: ${{matrix.otp}}
+          rebar3-version: ${{matrix.rebar3}}
+
+      - uses: actions/cache@v2
+        env:
+          cache-name: rebar3
+        with:
+          path: |
+            ~/.cache/rebar3
+            _build
+          key: ci-${{runner.os}}-${{env.cache-name}}-otp_${{matrix.otp}}-rebar_${{matrix.rebar3}}-${{hashFiles('rebar.lock')}}
+          restore-keys: |
+            ci-${{runner.os}}-${{env.cache-name}}-otp_${{matrix.otp}}-rebar_${{matrix.rebar3}}
+            ci-${{runner.os}}-${{env.cache-name}}-otp_${{matrix.otp}}
+
+      - name: Compile
+        run: rebar3 do clean, compile
+
+      - name: Dialyzer
+        run: rebar3 dialyzer