Test with 8.4.1

ndmitchell · web-flow · commit 5783c84f4116 · 2017-12-24T17:58:26.000Z
diff --git a/.travis.yml b/.travis.yml
@@ -6,6 +6,7 @@ env:
 - GHCVER=7.10.3
 - GHCVER=8.0.2
 - GHCVER=8.2.1
+- GHCVER=8.4.1
 - GHCVER=head
 
 script:
