add schema version

common/CHANGELOG.md

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+# Revision history for common
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

common/LICENSE

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+Copyright (c) 2024, Alexander Foremny
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Alexander Foremny nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

common/common.cabal

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+cabal-version:   3.4
+name:            common
+version:         0.1.0.0
+license:         BSD-3-Clause
+license-file:    LICENSE
+maintainer:      aforemny@posteo.de
+author:          Alexander Foremny
+build-type:      Simple
+extra-doc-files: CHANGELOG.md
+
+library
+    exposed-modules:    Version
+    hs-source-dirs:     src
+    default-language:   GHC2021
+    default-extensions: ViewPatterns
+    ghc-options:        -Wall
+    build-depends:
+        aeson,
+        base,
+        split,
+        text

common/src/Version.hs

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+module Version
+  ( Version (..),
+    versionToString,
+    versionFromText,
+    versionFromString,
+  )
+where
+
+import Data.Aeson qualified as A
+import Data.Aeson.Types qualified as A
+import Data.List
+import Data.List.Split
+import Data.Text qualified as T
+
+data Version = Version Int Int Int
+  deriving (Show, Eq)
+
+instance A.ToJSON Version where
+  toJSON =
+    A.toJSON . versionToString
+
+instance A.FromJSON Version where
+  parseJSON (A.String (versionFromText -> Just version)) = pure version
+  parseJSON v = A.typeMismatch "version" v
+
+versionToString :: Version -> String
+versionToString (Version major minor patch) =
+  intercalate "." (map show [major, minor, patch])
+
+versionFromString :: String -> Maybe Version
+versionFromString (map read . splitOn "." -> [major, minor, patch]) =
+  Just (Version major minor patch)
+versionFromString _ = Nothing
+
+versionFromText :: T.Text -> Maybe Version
+versionFromText = versionFromString . T.unpack