Add OSX target

.github/workflows/gradle.yml

@@ -1,13 +1,13 @@
 name: Gradle build
 
-on: [push]
+on: [ push ]
 
 jobs:
   build-ubuntu:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:
@@ -33,3 +33,33 @@ jobs:
           restore-keys: ${{ runner.os }}-konan-1.4.0
       - name: Build with Gradle
         run: ./gradlew -Dorg.gradle.daemon=false --build-cache :kmath-gsl:cinteropLibgslNative build
+  build-osx:
+    runs-on: macos-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 11
+        uses: actions/setup-java@v1
+        with:
+          java-version: 11
+      - name: Install gsl
+        run: brew install gsl
+      - name: Cache gradle
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: gradle_6_6_1
+          restore-keys: gradle_6_6_1
+
+      - name: Cache konan
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.konan/dependencies
+            ~/.konan/kotlin-native-prebuilt-macos-1.4.20-eap-37
+          key: ${{ runner.os }}-konan-1.4.0
+          restore-keys: ${{ runner.os }}-konan-1.4.0
+      - name: Build with Gradle
+        run: ./gradlew -Dorg.gradle.daemon=false --build-cache :kmath-gsl:cinteropLibgslNative build