travis-ci: Add ghc-8.6, Clean up a bit

.travis.yml

@@ -40,26 +40,6 @@ before_cache:
 #     addons: {apt: {packages: [libfcgi-dev,libgmp-dev]}}
 matrix:
   include:
-  # We grab the appropriate GHC and cabal-install versions from hvr's PPA. See:
-  # https://github.com/hvr/multi-ghc-travis
-  #- env: BUILD=cabal GHCVER=7.0.4 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
-  #  compiler: ": #GHC 7.0.4"
-  #  addons: {apt: {packages: [cabal-install-1.16,ghc-7.0.4,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  #- env: BUILD=cabal GHCVER=7.2.2 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
-  #  compiler: ": #GHC 7.2.2"
-  #  addons: {apt: {packages: [cabal-install-1.16,ghc-7.2.2,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  #- env: BUILD=cabal GHCVER=7.4.2 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
-  #  compiler: ": #GHC 7.4.2"
-  #  addons: {apt: {packages: [cabal-install-1.16,ghc-7.4.2,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  #- env: BUILD=cabal GHCVER=7.6.3 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
-  #  compiler: ": #GHC 7.6.3"
-  #  addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.3,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  #- env: BUILD=cabal GHCVER=7.8.4 CABALVER=1.18 HAPPYVER=1.19.5 ALEXVER=3.1.7
-  #  compiler: ": #GHC 7.8.4"
-  #  addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  #- env: BUILD=cabal GHCVER=7.10.3 CABALVER=1.22 HAPPYVER=1.19.5 ALEXVER=3.1.7
-  #  compiler: ": #GHC 7.10.3"
-  #  addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.3,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
   
   ##### OSX test via stack #####
 
@@ -79,6 +59,9 @@ matrix:
   - env: BUILD=cabal GHCVER=8.4.3 CABALVER=1.24 HAPPYVER=1.19.5 ALEXVER=3.1.7
     compiler: ": #cabal 8.4.3"
     addons: {apt: {packages: [cabal-install-1.24,ghc-8.4.3,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
+  - env: BUILD=cabal GHCVER=8.6.1 CABALVER=1.24 HAPPYVER=1.19.5 ALEXVER=3.1.7
+    compiler: ": #cabal 8.6.1"
+    addons: {apt: {packages: [cabal-install-1.24,ghc-8.6.1,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
 
   # Build with the newest GHC and cabal-install. This is an accepted failure,
   # see below.
@@ -106,18 +89,6 @@ matrix:
     compiler: ": #stack default"
     addons: {apt: {packages: [libgmp-dev]}}
 
-  #- env: BUILD=stack ARGS="--resolver lts-2"
-  #  compiler: ": #stack 7.8.4"
-  #  addons: {apt: {packages: [libgmp-dev]}}
-  #- env: BUILD=stack ARGS="--resolver lts-3"
-  #  compiler: ": #stack 7.10.2"
-  #  addons: {apt: {packages: [libgmp-dev]}}
-  #- env: BUILD=stack ARGS="--resolver lts-6"
-  #  compiler: ": #stack 7.10.3"
-  #  addons: {apt: {packages: [libgmp-dev]}}
-  #- env: BUILD=stack ARGS="--resolver lts-7"
-  #  compiler: ": #stack 8.0.1"
-  #  addons: {apt: {packages: [libgmp-dev]}}
   - env: BUILD=stack ARGS="--stack-yaml stack-8.0.2.yaml"
     compiler: ": #stack 8.0.2"
     addons: {apt: {packages: [libgmp-dev]}}
@@ -130,27 +101,6 @@ matrix:
     compiler: ": #stack nightly"
     addons: {apt: {packages: [libgmp-dev]}}
 
-  # Travis includes an macOS which is incompatible with GHC 7.8.4
-  #- env: BUILD=stack ARGS="--resolver lts-2"
-  #  compiler: ": #stack 7.8.4 osx"
-  #  os: osx
-
-  #- env: BUILD=stack ARGS="--resolver lts-3"
-  #  compiler: ": #stack 7.10.2 osx"
-  #  os: osx
-  #- env: BUILD=stack ARGS="--resolver lts-6"
-  #  compiler: ": #stack 7.10.3 osx"
-  #  os: osx
-  #- env: BUILD=stack ARGS="--resolver lts-7"
-  #  compiler: ": #stack 8.0.1 osx"
-  #  os: osx
-  #- env: BUILD=stack ARGS="--resolver lts-8"
-  #  compiler: ": #stack 8.0.2 osx"
-  #  os: osx
-  #- env: BUILD=stack ARGS="--resolver nightly"
-  #  compiler: ": #stack nightly osx"
-  #  os: osx
-
   allow_failures:
   #- env: BUILD=cabal GHCVER=head  CABALVER=head HAPPYVER=1.19.5 ALEXVER=3.1.7
   - env: BUILD=stack ARGS="--resolver nightly"

src/Language/Haskell/Brittany/Internal/Config.hs

@@ -231,6 +231,7 @@ cmdlineConfigParser = do
 readConfig
   :: MonadIO m => System.IO.FilePath -> MaybeT m (Maybe (CConfig Option))
 readConfig path = do
+  -- TODO: probably should catch IOErrors and then omit the existence check.
   exists <- liftIO $ System.Directory.doesFileExist path
   if exists
     then do