diff options
Diffstat (limited to 'testsuite/tests/deriving/should_run/drvrun019.hs')
| -rw-r--r-- | testsuite/tests/deriving/should_run/drvrun019.hs | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/testsuite/tests/deriving/should_run/drvrun019.hs b/testsuite/tests/deriving/should_run/drvrun019.hs new file mode 100644 index 0000000000..3fd8ccf025 --- /dev/null +++ b/testsuite/tests/deriving/should_run/drvrun019.hs @@ -0,0 +1,15 @@ +{-# LANGUAGE GeneralizedNewtypeDeriving #-} +
+-- Tests newtype deriving with
+-- a non-type constructor in the representation
+
+module Main where
+
+newtype Wrap m a = Wrap { unWrap :: m a }
+ deriving (Monad, Eq)
+
+foo :: Int -> Wrap IO a -> Wrap IO ()
+foo 0 a = return ()
+foo n a = do { a; foo (n-1) a }
+
+main = do { unWrap (foo 3 (Wrap (putChar 'x'))); putChar '\n' }
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