diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,121 +1,179 @@
-# This file has been generated -- see https://github.com/hvr/multi-ghc-travis
+# This Travis job script has been generated by a script via
+#
+#   haskell-ci '--output=.travis.yml' '--config=cabal.haskell-ci' 'cabal.project'
+#
+# For more information, see https://github.com/haskell-CI/haskell-ci
+#
+# version: 0.3.20190425
+#
 language: c
-sudo: false
-
+dist: xenial
+git:
+  # whether to recursively clone submodules
+  submodules: false
+notifications:
+  irc:
+    channels:
+      - irc.freenode.org#haskell-lens
+    skip_join: true
+    template:
+      - "\"\\x0313intervals\\x03/\\x0306%{branch}\\x03 \\x0314%{commit}\\x03 %{build_url} %{message}\""
 cache:
   directories:
-    - $HOME/.cabsnap
     - $HOME/.cabal/packages
-
+    - $HOME/.cabal/store
 before_cache:
-  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/build-reports.log
-  - rm -fv $HOME/.cabal/packages/hackage.haskell.org/00-index.tar
-
+  - rm -fv $CABALHOME/packages/hackage.haskell.org/build-reports.log
+  # remove files that are regenerated by 'cabal update'
+  - rm -fv $CABALHOME/packages/hackage.haskell.org/00-index.*
+  - rm -fv $CABALHOME/packages/hackage.haskell.org/*.json
+  - rm -fv $CABALHOME/packages/hackage.haskell.org/01-index.cache
+  - rm -fv $CABALHOME/packages/hackage.haskell.org/01-index.tar
+  - rm -fv $CABALHOME/packages/hackage.haskell.org/01-index.tar.idx
+  - rm -rfv $CABALHOME/packages/head.hackage
 matrix:
   include:
-    - env: CABALVER=1.24 GHCVER=7.0.4
-      compiler: ": #GHC 7.0.4"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-7.0.4], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=7.2.2
-      compiler: ": #GHC 7.2.2"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-7.2.2], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=7.4.2
-      compiler: ": #GHC 7.4.2"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-7.4.2], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=7.6.3
-      compiler: ": #GHC 7.6.3"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-7.6.3], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=7.8.4
-      compiler: ": #GHC 7.8.4"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-7.8.4], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=7.10.3
-      compiler: ": #GHC 7.10.3"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-7.10.3], sources: [hvr-ghc]}}
-    - env: CABALVER=1.24 GHCVER=8.0.2
-      compiler: ": #GHC 8.0.2"
-      addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.2], sources: [hvr-ghc]}}
-    - env: CABALVER=2.0 GHCVER=8.2.1
-      compiler: ": #GHC 8.2.1"
-      addons: {apt: {packages: [cabal-install-2.0,ghc-8.2.1], sources: [hvr-ghc]}}
-    - env: CABALVER=head GHCVER=head
-      compiler: ": #GHC head"
-      addons: {apt: {packages: [cabal-install-head,ghc-head], sources: [hvr-ghc]}}
-
+    - compiler: ghc-8.8.1
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.8.1","cabal-install-3.0"]}}
+      env: GHCHEAD=true
+    - compiler: ghc-8.6.5
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.6.5","cabal-install-2.4"]}}
+    - compiler: ghc-8.4.4
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.4.4","cabal-install-2.4"]}}
+    - compiler: ghc-8.2.2
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.2.2","cabal-install-2.4"]}}
+    - compiler: ghc-8.0.2
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.0.2","cabal-install-2.4"]}}
+    - compiler: ghc-7.10.3
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.10.3","cabal-install-2.4"]}}
+    - compiler: ghc-7.8.4
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.8.4","cabal-install-2.4"]}}
+    - compiler: ghc-7.6.3
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.6.3","cabal-install-2.4"]}}
+    - compiler: ghc-7.4.2
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.4.2","cabal-install-2.4"]}}
+    - compiler: ghc-7.2.2
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.2.2","cabal-install-2.4"]}}
+    - compiler: ghc-7.0.4
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.0.4","cabal-install-2.4"]}}
+    - compiler: ghc-head
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-head","cabal-install-head"]}}
+      env: GHCHEAD=true
   allow_failures:
-    - env: CABALVER=1.24 GHCVER=7.0.4
-    - env: CABALVER=1.24 GHCVER=7.2.2
-    - env: CABALVER=head GHCVER=head
-
+    - compiler: ghc-head
+    - compiler: ghc-7.0.4
+    - compiler: ghc-7.2.2
+    - compiler: ghc-8.8.1
 before_install:
- - unset CC
- - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
-
+  - HC=$(echo "/opt/$CC/bin/ghc" | sed 's/-/\//')
+  - HCPKG="$HC-pkg"
+  - unset CC
+  - CABAL=/opt/ghc/bin/cabal
+  - CABALHOME=$HOME/.cabal
+  - export PATH="$CABALHOME/bin:$PATH"
+  - TOP=$(pwd)
+  - HCNUMVER=$(( $(${HC} --numeric-version|sed -E 's/([0-9]+)\.([0-9]+)\.([0-9]+).*/\1 * 10000 + \2 * 100 + \3/') ))
+  - echo $HCNUMVER
+  - CABAL="$CABAL -vnormal+nowrap+markoutput"
+  - set -o pipefail
+  - |
+    echo 'function blue(s) { printf "\033[0;34m" s "\033[0m " }'           >> .colorful.awk
+    echo 'BEGIN { state = "output"; }'                                     >> .colorful.awk
+    echo '/^-----BEGIN CABAL OUTPUT-----$/ { state = "cabal" }'            >> .colorful.awk
+    echo '/^-----END CABAL OUTPUT-----$/ { state = "output" }'             >> .colorful.awk
+    echo '!/^(-----BEGIN CABAL OUTPUT-----|-----END CABAL OUTPUT-----)/ {' >> .colorful.awk
+    echo '  if (state == "cabal") {'                                       >> .colorful.awk
+    echo '    print blue($0)'                                              >> .colorful.awk
+    echo '  } else {'                                                      >> .colorful.awk
+    echo '    print $0'                                                    >> .colorful.awk
+    echo '  }'                                                             >> .colorful.awk
+    echo '}'                                                               >> .colorful.awk
+  - cat .colorful.awk
+  - |
+    color_cabal_output () {
+      awk -f $TOP/.colorful.awk
+    }
+  - echo text | color_cabal_output
 install:
- - cabal --version
- - echo "$(ghc --version) [$(ghc --print-project-git-commit-id 2> /dev/null || echo '?')]"
- - if [ -f $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz ];
-   then
-     zcat $HOME/.cabal/packages/hackage.haskell.org/00-index.tar.gz >
-          $HOME/.cabal/packages/hackage.haskell.org/00-index.tar;
-   fi
- - travis_retry cabal update -v
- - sed -i 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config
- - cabal install --only-dependencies --enable-tests --dry -v > installplan.txt
- - sed -i -e '1,/^Resolving /d' installplan.txt; cat installplan.txt
-
-# check whether current requested install-plan matches cached package-db snapshot
- - if diff -u installplan.txt $HOME/.cabsnap/installplan.txt;
-   then
-     echo "cabal build-cache HIT";
-     rm -rfv .ghc;
-     cp -a $HOME/.cabsnap/ghc $HOME/.ghc;
-     cp -a $HOME/.cabsnap/lib $HOME/.cabsnap/share $HOME/.cabsnap/bin $HOME/.cabal/;
-   else
-     echo "cabal build-cache MISS";
-     rm -rf $HOME/.cabsnap;
-     mkdir -p $HOME/.ghc $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin;
-     cabal install -j --only-dependencies --enable-tests;
-   fi
-
-# snapshot package-db on cache miss
- - if [ ! -d $HOME/.cabsnap ];
-   then
-      echo "snapshotting package-db to build-cache";
-      mkdir $HOME/.cabsnap;
-      cp -a $HOME/.ghc $HOME/.cabsnap/ghc;
-      cp -a $HOME/.cabal/lib $HOME/.cabal/share $HOME/.cabal/bin installplan.txt $HOME/.cabsnap/;
-   fi
-
-# 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.
+  - ${CABAL} --version
+  - echo "$(${HC} --version) [$(${HC} --print-project-git-commit-id 2> /dev/null || echo '?')]"
+  - TEST=--enable-tests
+  - if [ $HCNUMVER -lt 70600 ] ; then TEST=--disable-tests ; fi
+  - BENCH=--enable-benchmarks
+  - GHCHEAD=${GHCHEAD-false}
+  - rm -f $CABALHOME/config
+  - |
+    echo "verbose: normal +nowrap +markoutput"          >> $CABALHOME/config
+    echo "remote-build-reporting: anonymous"            >> $CABALHOME/config
+    echo "remote-repo-cache: $CABALHOME/packages"       >> $CABALHOME/config
+    echo "logs-dir:          $CABALHOME/logs"           >> $CABALHOME/config
+    echo "world-file:        $CABALHOME/world"          >> $CABALHOME/config
+    echo "extra-prog-path:   $CABALHOME/bin"            >> $CABALHOME/config
+    echo "symlink-bindir:    $CABALHOME/bin"            >> $CABALHOME/config
+    echo "installdir:        $CABALHOME/bin"            >> $CABALHOME/config
+    echo "build-summary:     $CABALHOME/logs/build.log" >> $CABALHOME/config
+    echo "store-dir:         $CABALHOME/store"          >> $CABALHOME/config
+    echo "install-dirs user"                            >> $CABALHOME/config
+    echo "  prefix: $CABALHOME"                         >> $CABALHOME/config
+    echo "repository hackage.haskell.org"               >> $CABALHOME/config
+    echo "  url: http://hackage.haskell.org/"           >> $CABALHOME/config
+  - |
+    if $GHCHEAD; then
+    echo "allow-newer: $($HCPKG list --simple-output | sed -E 's/([a-zA-Z-]+)-[0-9.]+/*:\1/g')" >> $CABALHOME/config
+    
+    echo "repository head.hackage"                                                        >> $CABALHOME/config
+    echo "   url: http://head.hackage.haskell.org/"                                       >> $CABALHOME/config
+    echo "   secure: True"                                                                >> $CABALHOME/config
+    echo "   root-keys: 07c59cb65787dedfaef5bd5f987ceb5f7e5ebf88b904bbd4c5cbdeb2ff71b740" >> $CABALHOME/config
+    echo "              2e8555dde16ebd8df076f1a8ef13b8f14c66bad8eafefd7d9e37d0ed711821fb" >> $CABALHOME/config
+    echo "              8f79fd2389ab2967354407ec852cbe73f2e8635793ac446d09461ffb99527f6e" >> $CABALHOME/config
+    echo "   key-threshold: 3"                                                            >> $CABALHOME/config
+    fi
+  - cat $CABALHOME/config
+  - rm -fv cabal.project cabal.project.local cabal.project.freeze
+  - travis_retry ${CABAL} v2-update -v
+  # Generate cabal.project
+  - rm -rf cabal.project cabal.project.local cabal.project.freeze
+  - touch cabal.project
+  - |
+    echo 'packages: "."' >> cabal.project
+  - |
+    echo "write-ghc-environment-files: always" >> cabal.project
+  - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | grep -vE -- '^(intervals)$' | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
+  - cat cabal.project || true
+  - cat cabal.project.local || true
+  - if [ -f "./configure.ac" ]; then (cd "." && autoreconf -i); fi
+  - ${CABAL} v2-freeze -w ${HC} ${TEST} ${BENCH} | color_cabal_output
+  - "cat cabal.project.freeze | sed -E 's/^(constraints: *| *)//' | sed 's/any.//'"
+  - rm  cabal.project.freeze
+  - ${CABAL} v2-build -w ${HC} ${TEST} ${BENCH} --dep -j2 all | color_cabal_output
 script:
- # -v2 provides useful information for debugging
- - cabal configure --enable-tests -v2
-
- # this builds all libraries and executables
- # (including tests/benchmarks)
- - cabal build
-
- # tests that a source-distribution can be generated
- - cabal sdist
-
- # check that the generated source-distribution can be built & installed
- - export SRC_TGZ=$(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
-
-notifications:
-  irc:
-    channels:
-      - "irc.freenode.org#haskell-lens"
-    skip_join: true
-    template:
-      - "\x0313intervals\x03/\x0306%{branch}\x03 \x0314%{commit}\x03 %{build_url} %{message}"
+  - DISTDIR=$(mktemp -d /tmp/dist-test.XXXX)
+  # Packaging...
+  - ${CABAL} v2-sdist all | color_cabal_output
+  # Unpacking...
+  - mv dist-newstyle/sdist/*.tar.gz ${DISTDIR}/
+  - cd ${DISTDIR} || false
+  - find . -maxdepth 1 -name '*.tar.gz' -exec tar -xvf '{}' \;
+  # Generate cabal.project
+  - rm -rf cabal.project cabal.project.local cabal.project.freeze
+  - touch cabal.project
+  - |
+    echo 'packages: "intervals-*/*.cabal"' >> cabal.project
+  - |
+    echo "write-ghc-environment-files: always" >> cabal.project
+  - "for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/-[^-]*$//' | grep -vE -- '^(intervals)$' | sed 's/^/constraints: /' | sed 's/$/ installed/' >> cabal.project.local; done"
+  - cat cabal.project || true
+  - cat cabal.project.local || true
+  # Building with tests and benchmarks...
+  # build & run tests, build benchmarks
+  - ${CABAL} v2-build -w ${HC} ${TEST} ${BENCH} all | color_cabal_output
+  # Testing...
+  - if [ $HCNUMVER -ge 70600 ] ; then ${CABAL} v2-test -w ${HC} ${TEST} ${BENCH} all | color_cabal_output ; fi
+  # cabal check...
+  - (cd intervals-* && ${CABAL} -vnormal check)
+  # haddock...
+  - ${CABAL} v2-haddock -w ${HC} ${TEST} ${BENCH} all | color_cabal_output
 
+# REGENDATA ["--output=.travis.yml","--config=cabal.haskell-ci","cabal.project"]
 # EOF
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,8 @@
+0.9 [2019.05.10]
+----------------
+* Remove the `Foldable` instances for the `Interval` types from
+  `Numeric.Interval` and `Numeric.Interval.NonEmpty`.
+
 0.8.1
 -----
 * Support `doctest-0.12`
diff --git a/intervals.cabal b/intervals.cabal
--- a/intervals.cabal
+++ b/intervals.cabal
@@ -1,5 +1,5 @@
 name:              intervals
-version:           0.8.1
+version:           0.9
 synopsis:          Interval Arithmetic
 description:
   A 'Numeric.Interval.Interval' is a closed, convex set of floating point values.
@@ -17,7 +17,17 @@
 category:           Math
 build-type:         Custom
 cabal-version:      >=1.8
-tested-with:        GHC == 7.4.2, GHC == 7.6.1, GHC == 7.6.3, GHC == 7.8.4, GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.1
+tested-with:        GHC == 7.0.4
+                  , GHC == 7.2.2
+                  , GHC == 7.4.2
+                  , GHC == 7.6.3
+                  , GHC == 7.8.4
+                  , GHC == 7.10.3
+                  , GHC == 8.0.2
+                  , GHC == 8.2.2
+                  , GHC == 8.4.4
+                  , GHC == 8.6.5
+                  , GHC == 8.8.1
 extra-source-files:
   .travis.yml
   CHANGELOG.markdown
@@ -79,13 +89,13 @@
   ghc-options:    -Wall -threaded
   hs-source-dirs: tests
 
-  if !flag(test-doctests)
+  if !flag(test-doctests) || !impl(ghc >= 7.6)
     buildable: False
   else
     build-depends:
-      base,
+      base           >= 4.6,
       directory      >= 1.0,
-      doctest        >= 0.11.1 && <0.13,
+      doctest        >= 0.11.1 && < 0.17,
       filepath,
       intervals,
       QuickCheck,
diff --git a/src/Numeric/Interval/Internal.hs b/src/Numeric/Interval/Internal.hs
--- a/src/Numeric/Interval/Internal.hs
+++ b/src/Numeric/Interval/Internal.hs
@@ -58,13 +58,7 @@
 
 import Control.Exception as Exception
 import Data.Data
-import Data.Foldable hiding (minimum, maximum, elem, notElem
-#if __GLASGOW_HASKELL__ >= 710
-  , null
-#endif
-  )
 import Data.Function (on)
-import Data.Monoid
 #if __GLASGOW_HASKELL__ >= 704
 import GHC.Generics
 #endif
@@ -84,11 +78,6 @@
 #endif
 #endif
   )
-
-instance Foldable Interval where
-  foldMap f (I a b) = f a `mappend` f b
-  foldMap _ Empty = mempty
-  {-# INLINE foldMap #-}
 
 infix 3 ...
 infixl 6 +/-
diff --git a/src/Numeric/Interval/NonEmpty/Internal.hs b/src/Numeric/Interval/NonEmpty/Internal.hs
--- a/src/Numeric/Interval/NonEmpty/Internal.hs
+++ b/src/Numeric/Interval/NonEmpty/Internal.hs
@@ -55,8 +55,6 @@
 
 import Control.Exception as Exception
 import Data.Data
-import Data.Foldable hiding (minimum, maximum, elem, notElem)
-import Data.Monoid
 #if __GLASGOW_HASKELL__ >= 704
 import GHC.Generics
 #endif
@@ -90,10 +88,6 @@
 #endif
 #endif
   )
-
-instance Foldable Interval where
-  foldMap f (I a b) = f a `mappend` f b
-  {-# INLINE foldMap #-}
 
 infix 3 ...