Add Show and Eq instances to :& (bitemyapp#317)

* Add Show and Eq for testing

* changelog, cabal

* Changelog entry

changelog.md

@@ -1,3 +1,10 @@
+
+3.5.5.0
+=======
+- @parsonsmatt
+    - [#317](https://github.com/bitemyapp/esqueleto/pull/317)
+        - Add `Eq` and `Show` instances to `:&`
+
 3.5.4.2
 =======
 - @parsonsmatt

esqueleto.cabal

@@ -1,7 +1,8 @@
 cabal-version: 1.12
 
 name:           esqueleto
-version:        3.5.4.2
+
+version:        3.5.5.0
 synopsis:       Type-safe EDSL for SQL queries on persistent backends.
 description:    @esqueleto@ is a bare bones, type-safe EDSL for SQL queries that works with unmodified @persistent@ SQL backends.  Its language closely resembles SQL, so you don't have to learn new concepts, just new syntax, and it's fairly easy to predict the generated SQL and optimize it for your backend. Most kinds of errors committed when writing SQL are caught as compile-time errors---although it is possible to write type-checked @esqueleto@ queries that fail at runtime.
                 .

src/Database/Esqueleto/Experimental/From/Join.hs

@@ -39,6 +39,7 @@ import GHC.TypeLits
 -- See the examples at the beginning of this module to see how this
 -- operator is used in 'JOIN' operations.
 data (:&) a b = a :& b
+    deriving (Eq, Show)
 infixl 2 :&
 
 instance (ToMaybe a, ToMaybe b) => ToMaybe (a :& b) where