Derive Read for Scheme using deriving in BaseUrl (#1848)

* Derive `Read` for `Scheme` using `deriving` in `BaseUrl` (#1847)

* Add changelog entry file for PR #1848

Author: nattybear

changelog.d/pr-1848

@@ -0,0 +1,12 @@
+synopsis: Derive `Read` instance for `Scheme` in `BaseUrl`
+packages: servant-client-core
+prs: #1848
+issues: #1847
+description: {
+  Added a `Read` instance to the `Scheme` data type in `BaseUrl` via the
+  `deriving` clause. This allows parsing `Scheme` values from strings using
+  the standard `Read` mechanism.
+
+  This change improves compatibility with libraries like `config-ini`
+  that rely on the `Read` typeclass for parsing configuration values.
+}

servant-client-core/src/Servant/Client/Core/BaseUrl.hs

@@ -32,7 +32,7 @@ data Scheme
     Http
   | -- | https://
     Https
-  deriving (Data, Eq, Generic, Lift, Ord, Show)
+  deriving (Data, Eq, Generic, Lift, Ord, Read, Show)
 
 -- | Simple data type to represent the target of HTTP requests
 --   for servant's automatically-generated clients.