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-rw-r--r--testsuite/tests/gadt/gadt-fd.hs23
1 files changed, 23 insertions, 0 deletions
diff --git a/testsuite/tests/gadt/gadt-fd.hs b/testsuite/tests/gadt/gadt-fd.hs
new file mode 100644
index 0000000000..4db7b62889
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+++ b/testsuite/tests/gadt/gadt-fd.hs
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+{-# LANGUAGE GADTs #-}
+
+-- Trac #345
+
+module ShouldCompile where
+
+data Succ n
+data Zero
+
+class Plus x y z | x y -> z
+instance Plus Zero x x
+instance Plus x y z => Plus (Succ x) y (Succ z)
+
+infixr 5 :::
+
+data List :: * -> * -> * where
+ Nil :: List a Zero
+ (:::) :: a -> List a n -> List a (Succ n)
+
+append :: Plus x y z => List a x -> List a y -> List a z
+append Nil ys = ys
+append (x ::: xs) ys = x ::: append xs ys
+