Set -Wall and fix warnings

I think setting -Wall is a sensible default and @dmjio confirmed this. After
putting this in my project's .ghci file, a few dozen warnings emerged. This
commit changes the code that causes the warnings.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/Utils.hs b/src/Utils.hs
index 78ee93ec95de..48c33af0796d 100644
--- a/src/Utils.hs
+++ b/src/Utils.hs
@@ -5,4 +5,5 @@ import Data.Function ((&))
 --------------------------------------------------------------------------------
 
 -- | Prefer this operator to the ampersand for stylistic reasons.
+(|>) :: a -> (a -> b) -> b
 (|>) = (&)