CI: Add a GitHub workflow

.github/workflows/ci.yml

@@ -0,0 +1,82 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: 'Build'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+
+      - name: Build
+        run: cargo build --verbose
+
+  run_unit_tests:
+    name: 'Run unit tests'
+    needs: [build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+
+      - name: Test
+        run: cargo test
+
+  type_check_prelude:
+    name: 'Type check Prelude.hs'
+    needs: [build]
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+
+      - name: 'Type check Prelude.hs'
+        run: cargo run
+
+  check_formatting:
+    name: 'Check formatting'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get Rust stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            components: rustfmt
+            override: true
+
+      - name: Check formatting
+        run: cargo fmt --all -- --check
+
+  check_lints:
+    name: 'Check lints'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get Rust stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: stable
+            override: true
+
+      - name: Check lints
+        run: cargo clippy --all-targets --all