diff --git a/.travis.yml b/.travis.yml
index 5e41e673..49261a7f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,3 @@
-
 language: c
 sudo: false
 
@@ -19,10 +18,18 @@ matrix:
       addons: {apt: {packages: [libgmp-dev]}}
     - env: STACK_RESOLVER=lts-7.18
       addons: {apt: {packages: [libgmp-dev]}}
-    - env: STACK_RESOLVER=lts-6.29
-      addons: {apt: {packages: [libgmp-dev]}}
+    - env: GHCVER=8.0.1 CABALVER=1.24 CABAL_JOBS=-j
+      addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.1], sources: [hvr-ghc]}}
+    - env: GHCVER=7.6.3 CABALVER=1.16
+      addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.3], sources: [hvr-ghc]}}
     - env: DEBIANVER=wheezy GHCVER=7.4.1 CABALVER=1.16 NO_CABAL_CACHE=1
       addons: {apt: {packages: [cabal-install-1.16,ghc-7.4.1], sources: [hvr-ghc]}}
+    - env: STACK_RESOLVER=lts-6.29
+      addons: {apt: {packages: [libgmp-dev]}}
+    - env: GHCVER=7.10.3 CABALVER=1.22 CABAL_JOBS=-j
+      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.3], sources: [hvr-ghc]}}
+    - env: GHCVER=7.8.4 CABALVER=1.18 CABAL_JOBS=-j
+      addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4], sources: [hvr-ghc]}}
     - env: GHCVER=7.4.1 CABALVER=1.16
       addons: {apt: {packages: [cabal-install-1.16,ghc-7.4.1], sources: [hvr-ghc]}}
     - env: GHCVER=7.4.2 CABALVER=1.16
@@ -31,24 +38,16 @@ matrix:
       addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.1], sources: [hvr-ghc]}}
     - env: GHCVER=7.6.2 CABALVER=1.16
       addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.2], sources: [hvr-ghc]}}
-    - env: GHCVER=7.6.3 CABALVER=1.16
-      addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.3], sources: [hvr-ghc]}}
     - env: GHCVER=7.8.1 CABALVER=1.18 CABAL_JOBS=-j
       addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.1], sources: [hvr-ghc]}}
     - env: GHCVER=7.8.2 CABALVER=1.18 CABAL_JOBS=-j
       addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.2], sources: [hvr-ghc]}}
     - env: GHCVER=7.8.3 CABALVER=1.18 CABAL_JOBS=-j
       addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.3], sources: [hvr-ghc]}}
-    - env: GHCVER=7.8.4 CABALVER=1.18 CABAL_JOBS=-j
-      addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4], sources: [hvr-ghc]}}
     - env: GHCVER=7.10.1 CABALVER=1.22 CABAL_JOBS=-j
       addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.1], sources: [hvr-ghc]}}
     - env: GHCVER=7.10.2 CABALVER=1.22 CABAL_JOBS=-j
       addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.2], sources: [hvr-ghc]}}
-    - env: GHCVER=7.10.3 CABALVER=1.22 CABAL_JOBS=-j
-      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.3], sources: [hvr-ghc]}}
-    - env: GHCVER=8.0.1 CABALVER=1.24 CABAL_JOBS=-j
-      addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.1], sources: [hvr-ghc]}}
 
 before_install:
  ## - cat /proc/cpuinfo
@@ -64,6 +63,13 @@ before_install:
          export CABAL_CONSTRAINTS='--constraint=transformers==0.3.0.0 --constraint=containers==0.4.2.1 --constraint=bytestring==0.9.2.1 --constraint=text==0.11.2.0 --constraint=time==1.4 --constraint=dlist==0.5 --constraint=convertible==1.0.11.1 --constraint=HDBC==2.3.1.1' ;
          ;;
        '')
+         case "$GHCVER" in
+           7.6.*|7.4.*)
+              export CABAL_CONSTRAINTS='--constraint=time==1.4'
+              ;;
+           *)
+              ;;
+         esac ;
          ;;
        *)
          echo "Unsupported DEBIANVER, $DEBIANVER" ;
diff --git a/travis-CI/cabal-hvr-ghc/install.sh b/travis-CI/cabal-hvr-ghc/install.sh
index f0718b36..6a7ad20f 100755
--- a/travis-CI/cabal-hvr-ghc/install.sh
+++ b/travis-CI/cabal-hvr-ghc/install.sh
@@ -26,43 +26,47 @@ custom_retry cabal update -v
 sed -i 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config
 
 install_package() {
-    id="$1"
-
-    if [ x"$id" = x ]; then
-        install_plan=installplan.txt
-    else
-        install_plan=installplan-${id}.txt
-    fi
-
-    cabal install $CABAL_CONSTRAINTS --only-dependencies --enable-tests --enable-benchmarks --dry -v > ${install_plan}
-    sed -i -e '1,/^Resolving /d' ${install_plan}; cat ${install_plan}
-
-    cabsnap_dir=$HOME/.cabsnap/s-${CABALVER}
-
-    # check whether current requested install-plan matches cached package-db snapshot
-    if [ x"NO_CABAL_CACHE" = x ] && diff -u ${cabsnap_dir}/${install_plan} ${install_plan};
-    then
-        echo "cabal build-cache HIT";
-        rm -rfv .ghc;
-        cp -a ${cabsnap_dir}/ghc $HOME/.ghc;
-        cp -a ${cabsnap_dir}/lib ${cabsnap_dir}/share ${cabsnap_dir}/bin $HOME/.cabal/;
-    else
-        echo "cabal build-cache MISS";
-        rm -rf ${cabsnap_dir};
-        mkdir -p $HOME/.ghc $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin;
-        cabal install $CABAL_JOBS $CABAL_CONSTRAINTS --only-dependencies --enable-tests --enable-benchmarks;
-    fi
-
-    # snapshot package-db on cache miss
-    if [ ! -d ${cabsnap_dir} ];
-    then
-        echo "snapshotting package-db to build-cache";
-        mkdir -p ${cabsnap_dir};
-        cp -a $HOME/.ghc ${cabsnap_dir}/ghc;
-        cp -a $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin ${install_plan} ${cabsnap_dir}/;
-    fi
+    cabal install $CABAL_JOBS $CABAL_CONSTRAINTS --only-dependencies --enable-tests --enable-benchmarks
 }
 
+# install_package() {
+#     id="$1"
+
+#     if [ x"$id" = x ]; then
+#         install_plan=installplan.txt
+#     else
+#         install_plan=installplan-${id}.txt
+#     fi
+
+#     cabal install $CABAL_CONSTRAINTS --only-dependencies --enable-tests --enable-benchmarks --dry -v > ${install_plan}
+#     sed -i -e '1,/^Resolving /d' ${install_plan}; cat ${install_plan}
+
+#     cabsnap_dir=$HOME/.cabsnap/s-${CABALVER}
+
+#     # check whether current requested install-plan matches cached package-db snapshot
+#     if [ x"NO_CABAL_CACHE" = x ] && diff -u ${cabsnap_dir}/${install_plan} ${install_plan};
+#     then
+#         echo "cabal build-cache HIT";
+#         rm -rfv .ghc;
+#         cp -a ${cabsnap_dir}/ghc $HOME/.ghc;
+#         cp -a ${cabsnap_dir}/lib ${cabsnap_dir}/share ${cabsnap_dir}/bin $HOME/.cabal/;
+#     else
+#         echo "cabal build-cache MISS";
+#         rm -rf ${cabsnap_dir};
+#         mkdir -p $HOME/.ghc $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin;
+#         cabal install $CABAL_JOBS $CABAL_CONSTRAINTS --only-dependencies --enable-tests --enable-benchmarks;
+#     fi
+
+#     # snapshot package-db on cache miss
+#     if [ ! -d ${cabsnap_dir} ];
+#     then
+#         echo "snapshotting package-db to build-cache";
+#         mkdir -p ${cabsnap_dir};
+#         cp -a $HOME/.ghc ${cabsnap_dir}/ghc;
+#         cp -a $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin ${install_plan} ${cabsnap_dir}/;
+#     fi
+# }
+
 if [ x"$dirs" = x ]; then
     install_package ''
 else
diff --git a/travis-CI/stack/script.sh b/travis-CI/stack/script.sh
index 103ecca7..6baaff79 100755
--- a/travis-CI/stack/script.sh
+++ b/travis-CI/stack/script.sh
@@ -8,6 +8,8 @@ set -x
 
 script_build() {
     STACK_YAML=stack-travis.yaml stack build
+    STACK_YAML=stack-travis.yaml stack test
+    ## '--coverage' may change result of fail or success
     STACK_YAML=stack-travis.yaml stack test --coverage
 }
 
diff --git a/travis-CI/stack/template.yaml b/travis-CI/stack/template.yaml
index 91ae827d..4286e4cc 100644
--- a/travis-CI/stack/template.yaml
+++ b/travis-CI/stack/template.yaml
@@ -8,4 +8,3 @@ flags: {}
 extra-package-dbs: []
 system-ghc: false
 install-ghc: true
-skip-ghc-check: true