Run tests with multiple GHC versions on Travis-CI

.travis.yml

@@ -1 +1,36 @@
-language: haskell
+env:
+  - GHCVER=7.0.4
+  - GHCVER=7.2.2
+  - GHCVER=7.4.2
+  - GHCVER=7.6.3
+  - GHCVER=head
+
+before_install:
+  - sudo add-apt-repository -y ppa:hvr/ghc
+  - sudo apt-get update
+  - sudo apt-get install cabal-install-1.18 ghc-$GHCVER happy
+  - export PATH=/opt/ghc/$GHCVER/bin:$PATH
+
+install:
+  - cabal-1.18 update
+  - cabal-1.18 install --only-dependencies --enable-tests
+
+script:
+  - cabal-1.18 configure --enable-tests
+  - cabal-1.18 build
+  - cabal-1.18 test
+  - cabal-1.18 check
+  - cabal-1.18 sdist
+  # The following scriptlet checks that the resulting source distribution can be built & installed
+  - export SRC_TGZ=$(cabal-1.18 info . | awk '{print $2 ".tar.gz";exit}');
+    cd dist/;
+    if [ -f "$SRC_TGZ" ]; then
+      cabal-1.18 install --enable-tests "$SRC_TGZ";
+    else
+      echo "expected '$SRC_TGZ' not found";
+      exit 1;
+    fi
+
+matrix:
+  allow_failures:
+    - env: GHCVER=head