diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # shake-cabal
 
+## 0.2.1.0
+
+  * Add `hsOracle` and `cabalOracle`
+
 ## 0.2.0.0
 
   * More precise `HsCompiler` type
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright Vanessa McHale (c) 2018
+Copyright Vanessa McHale (c) 2018-2019
 
 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 
diff --git a/shake-cabal.cabal b/shake-cabal.cabal
--- a/shake-cabal.cabal
+++ b/shake-cabal.cabal
@@ -1,9 +1,9 @@
 cabal-version: 1.18
 name: shake-cabal
-version: 0.2.0.0
+version: 0.2.1.0
 license: BSD3
 license-file: LICENSE
-copyright: Copyright: (c) 2018 Vanessa McHale
+copyright: Copyright: (c) 2018-2019 Vanessa McHale
 maintainer: vanessa.mchale@iohk.io
 author: Vanessa McHale
 bug-reports: https://hub.darcs.net/vmchale/ats/issues
@@ -29,7 +29,11 @@
     exposed-modules:
         Development.Shake.Cabal
     hs-source-dirs: src
+    other-modules:
+        Development.Shake.Cabal.Oracles
     default-language: Haskell2010
+    other-extensions: DeriveAnyClass DeriveGeneric DeriveDataTypeable
+                      TypeFamilies
     ghc-options: -Wall
     build-depends:
         base >=4.8 && <5,
@@ -37,14 +41,17 @@
         Cabal >=2.2,
         directory -any,
         composition-prelude -any,
-        filepath -any
-    
+        filepath -any,
+        deepseq -any,
+        hashable -any,
+        binary -any
+
     if flag(development)
         ghc-options: -Werror
-    
+
     if impl(ghc >=8.0)
         ghc-options: -Wincomplete-uni-patterns -Wincomplete-record-updates
                      -Wredundant-constraints -Wnoncanonical-monad-instances
-    
+
     if impl(ghc >=8.4)
         ghc-options: -Wmissing-export-lists
diff --git a/src/Development/Shake/Cabal.hs b/src/Development/Shake/Cabal.hs
--- a/src/Development/Shake/Cabal.hs
+++ b/src/Development/Shake/Cabal.hs
@@ -2,6 +2,9 @@
                                , getCabalDepsV
                                , getCabalDepsA
                                , shakeVerbosityToCabalVerbosity
+                               -- * Oracles
+                               , hsOracle
+                               , cabalOracle
                                -- * Types
                                , HsCompiler (..)
                                -- * Helper functions
@@ -19,6 +22,7 @@
 import           Data.Maybe                             (catMaybes)
 import           Development.Shake                      hiding (doesFileExist)
 import qualified Development.Shake                      as Shake
+import           Development.Shake.Cabal.Oracles
 import           Distribution.ModuleName
 import           Distribution.PackageDescription
 import           Distribution.PackageDescription.Parsec
@@ -31,12 +35,6 @@
 import           System.Directory                       (doesFileExist)
 import           System.FilePath                        (pathSeparator)
 import           System.Info                            (arch, os)
-
-data HsCompiler = GHC { _pref :: Maybe String -- ^ Target architecture
-                      , _suff :: Maybe String -- ^ Compiler version
-                      }
-                | GHCJS { _suff :: Maybe String -- ^ Compiler version
-                        }
 
 hsCompiler :: HsCompiler -> String
 hsCompiler (GHC Nothing Nothing)       = "ghc"
diff --git a/src/Development/Shake/Cabal/Oracles.hs b/src/Development/Shake/Cabal/Oracles.hs
new file mode 100644
--- /dev/null
+++ b/src/Development/Shake/Cabal/Oracles.hs
@@ -0,0 +1,45 @@
+{-# LANGUAGE DeriveAnyClass     #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveGeneric      #-}
+{-# LANGUAGE TypeFamilies       #-}
+
+-- this is in a separate module because the TypeFamilies extension apparently
+-- causes previously valid code to not typecheck... ok
+module Development.Shake.Cabal.Oracles ( hsOracle
+                                       , cabalOracle
+                                       , HsCompiler (..)
+                                       ) where
+
+import           Control.DeepSeq   (NFData)
+import           Data.Binary       (Binary)
+import           Data.Hashable     (Hashable)
+import           Data.Typeable     (Typeable)
+import           Development.Shake
+import           GHC.Generics      (Generic)
+
+-- | Use this for tracking 'HsCompiler'
+--
+-- @since 0.2.1.0
+hsOracle :: (RuleResult q ~ a, q ~ a, ShakeValue q) => Rules (q -> Action a)
+hsOracle = addOracle pure
+
+-- | Use this to track the version of cabal globally available
+--
+-- @since 0.2.1.0
+cabalOracle :: Rules (CabalVersion -> Action String)
+cabalOracle = addOracle $ \CabalVersion -> do
+    (Stdout out) <- command [] "cabal" [ "--numeric-version"]
+    pure out
+
+data HsCompiler = GHC { _pref :: Maybe String -- ^ Target architecture
+                      , _suff :: Maybe String -- ^ Compiler version
+                      }
+                | GHCJS { _suff :: Maybe String -- ^ Compiler version
+                        }
+                deriving (Generic, Show, Eq, NFData, Hashable, Binary, Typeable)
+
+data CabalVersion = CabalVersion
+    deriving (Generic, Show, Typeable, Eq, Hashable, Binary, NFData)
+
+type instance RuleResult HsCompiler = HsCompiler
+type instance RuleResult CabalVersion = String