Backwards compatibility

obsidiansystems · Nov 18, 2020 · b442eeb · b442eeb
1 parent 4f2a06f
commit b442eeb
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Showing 3 changed files with 20 additions and 5 deletions.
diff --git a/aeson-gadt-th.cabal b/aeson-gadt-th.cabal
@@ -1,4 +1,4 @@
-cabal-version: 2.0
+cabal-version: 1.24
 name: aeson-gadt-th
 version: 0.2.4
 synopsis: Derivation of Aeson instances for GADTs
@@ -21,12 +21,12 @@ flag build-readme
 library
   exposed-modules: Data.Aeson.GADT.TH
   build-depends: base >= 4.8 && < 4.15
-               , aeson >= 1.4 && < 1.5
+               , aeson >= 1.3 && < 1.5
                , containers >= 0.5 && < 0.7
-               , dependent-sum >= 0.6.1 && < 0.8
+               , dependent-sum >= 0.4 && < 0.8
                , transformers >= 0.5 && < 0.6
-               , template-haskell >= 2.11.0 && < 2.17
-               , th-abstraction >= 0.3.1.0 && < 0.4
+               , template-haskell >= 2.11.0 && < 2.16
+               , th-abstraction >= 0.2.8.0 && < 0.4
                , th-extras >= 0.0.0.4 && < 0.1
   if impl(ghc < 8.2)
     build-depends: dependent-sum < 0.6.2.2

diff --git a/src/Data/Aeson/GADT/TH.hs b/src/Data/Aeson/GADT/TH.hs
@@ -7,6 +7,7 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE PatternGuards #-}
+{-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE QuasiQuotes #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
@@ -51,6 +52,12 @@ import Language.Haskell.TH.Datatype
 
 import System.IO (hFlush, stdout)
 
+#if MIN_VERSION_dependent_sum(0,5,0)
+#else
+pattern Some :: tag a -> Some tag
+pattern Some x = This x
+#endif
+
 -- Do not export this type family, it must remain empty. It's used as a way to trick GHC into not unifying certain type variables.
 type family Skolem :: k -> k
 

diff --git a/test/Test.hs b/test/Test.hs
@@ -1,7 +1,9 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE QuasiQuotes #-}
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE TemplateHaskell #-}
@@ -15,6 +17,12 @@ import Data.Aeson.GADT.TH
 import Expectations
 import Test.Hspec
 
+#if MIN_VERSION_dependent_sum(0,5,0)
+#else
+pattern Some :: tag a -> Some tag
+pattern Some x = This x
+#endif
+
 main :: IO ()
 main = hspec $ do
   describe "aeson-gadt-th" $ do