Update appveyor.yml.

appveyor.yml

@@ -1,6 +1,9 @@
 install:
-  - choco install HaskellPlatform -version 2014.2.0.0
-  - SET PATH=C:\Program Files\Haskell Platform\2014.2.0.0\bin;C:\Program Files\Haskell Platform\2014.2.0.0\mingw\bin;C:\Program Files\Haskell Platform\2014.2.0.0\lib\extralibs\bin;%PATH%
+  - choco install ghc -version 7.10.3
+  - SET PATH=%PATH%;C:\tools\ghc\ghc-7.10.3\bin
+  - curl -o cabal.zip https://www.haskell.org/cabal/release/cabal-install-1.24.0.0-rc1/cabal-install-1.24.0.0-rc1-x86_64-unknown-mingw32.zip
+  - 7z x cabal.zip
+  - cabal --version
   - cabal update
 
 build_script:
@@ -9,7 +12,7 @@ build_script:
 
   # 'echo "" |' works around an AppVeyor issue:
   # https://github.com/commercialhaskell/stack/issues/1097#issuecomment-145747849
-  - echo "" | cabal install --only-dependencies --enable-tests
+  - echo "" | ..\cabal install --only-dependencies --enable-tests
 
   - Setup configure --user --ghc-option=-Werror --enable-tests
   - Setup build
@@ -18,7 +21,7 @@ build_script:
   - Setup install
   - cd ..\cabal-install
   - ghc --make -threaded -i -i. Setup.hs -Wall -Werror
-  - echo "" | cabal install --only-dependencies --enable-tests --force-reinstalls
-  - Setup configure --user --ghc-option=-Werror --enable-tests
-  - Setup build
-  - Setup test unit-tests --show-details=streaming --test-option=--pattern=!FileMonitor
+  - echo "" | ..\cabal install --only-dependencies --enable-tests --force-reinstalls
+  - ..\cabal configure --user --ghc-option=-Werror --enable-tests
+  - ..\cabal build
+  - ..\cabal test unit-tests --show-details=streaming --test-option=--pattern=!FileMonitor