refactor: Carve CLI and Version modules out of Config (#1806)

src/PostgREST/Version.hs

@@ -0,0 +1,29 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+module PostgREST.Version
+  ( docsVersion
+  , prettyVersion
+  ) where
+
+import qualified Data.Text as T
+
+import Data.Version       (versionBranch)
+import Development.GitRev (gitHash)
+import Paths_postgrest    (version)
+
+import Protolude
+
+
+-- | User friendly version number
+prettyVersion :: Text
+prettyVersion =
+  T.intercalate "." (map show $ versionBranch version) <> gitRev
+  where
+    gitRev =
+      if $(gitHash) == "UNKNOWN"
+        then mempty
+        else " (" <> T.take 7 $(gitHash) <> ")"
+
+-- | Version number used in docs
+docsVersion :: Text
+docsVersion = "v" <> T.dropEnd 1 (T.dropWhileEnd (/= '.') prettyVersion)