Ghc major version whitelist is now drawn from stackage-content

Data/GhcLinks.hs

@@ -6,6 +6,7 @@ module Data.GhcLinks
 import ClassyPrelude.Yesod
 import Control.Monad.State.Strict (modify, execStateT)
 import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Yaml as Yaml
 import Filesystem (readTextFile, isFile)
 
 import Types
@@ -18,16 +19,16 @@ newtype GhcLinks = GhcLinks
 supportedArches :: [SupportedArch]
 supportedArches = [minBound .. maxBound]
 
-supportedGhcMajorVersions :: [GhcMajorVersion]
-supportedGhcMajorVersions = ["7.8", "7.10"]
-
-
 readGhcLinks :: FilePath -> IO GhcLinks
 readGhcLinks dir = do
+  let ghcMajorVersionsPath = dir </> "supported-ghc-major-versions.yaml"
+  Yaml.decodeFile (fpToString ghcMajorVersionsPath) >>= \case
+    Nothing -> return $ GhcLinks HashMap.empty
+    Just (ghcMajorVersions :: [GhcMajorVersion]) -> do
       let opts =
             [ (arch, ver)
             | arch <- supportedArches
-        , ver <- supportedGhcMajorVersions
+            , ver <- ghcMajorVersions
             ]
       hashMap <- flip execStateT HashMap.empty
                $ forM_ opts $ \(arch, ver) -> do