Attempted update to Travis config

.travis.yml

@@ -11,3 +11,39 @@ script:
     - mega-sdist --test
     - cabal install hspec cabal-meta cabal-src
     - cabal-meta install --force-reinstalls
+
+# NB: don't set `language: haskell` here
+
+# The following enables several GHC versions to be tested; often it's enough to test only against the last release in a major GHC version. Feel free to omit lines listings versions you don't need/want testing for.
+env:
+ - CABALVER=1.20 GHCVER=7.6.3
+ - CABALVER=1.20 GHCVER=7.8.4
+ #- CABALVER=1.22 GHCVER=7.10.1
+ #- CABALVER=head GHCVER=head   # see section about GHC HEAD snapshots
+
+# Note: the distinction between `before_install` and `install` is not important.
+before_install:
+ - travis_retry sudo add-apt-repository -y ppa:hvr/ghc
+ - travis_retry sudo apt-get update
+ - travis_retry sudo apt-get install cabal-install-$CABALVER ghc-$GHCVER # see note about happy/alex
+ - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
+
+install:
+ - cabal --version
+ - echo "$(ghc --version) [$(ghc --print-project-git-commit-id 2> /dev/null || echo '?')]"
+ - travis_retry cabal update
+ - cabal install cabal-meta alex happy
+
+# Here starts the actual work to be performed for the package under test; any command which exits with a non-zero exit code causes the build to fail.
+script:
+ - cabal-meta install --only-dependencies --run-tests --enable-benchmarks --force-reinstalls
+
+# The following scriptlet checks that the resulting source distribution can be built & installed
+ - export SRC_TGZ=$(cabal info . | awk '{print $2 ".tar.gz";exit}') ;
+   cd dist/;
+   if [ -f "$SRC_TGZ" ]; then
+      cabal install --force-reinstalls "$SRC_TGZ";
+   else
+      echo "expected '$SRC_TGZ' not found";
+      exit 1;
+   fi