39 lines
1.1 KiB
Haskell
39 lines
1.1 KiB
Haskell
{-# OPTIONS -cpp #-}
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--
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-- Should evaluate to '3', unless something goes wrong.
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--
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-- Not so bad to use AltData, as it is already derived for all the basic
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-- types. Then, just replace deriving Typeable, with hand-derived
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-- instance of Typeable (see hs-plugins/testsuite/eval/eval_fn1/Poly.hs
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--
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--
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#include "../../../config.h"
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import System.Eval
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import AltData.Dynamic
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main = do
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a <- return $ toDyn (3::Integer)
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-- so, we try to compile a function that takes a dyn.
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-- looks like with GHC 6.4, we need to make sure the package.confs work:
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m_b <- unsafeEval_ "\\dyn -> fromDyn dyn (7 :: Integer)"
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["AltData.Dynamic"]
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[ ]
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[ ]
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[]
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case m_b of
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Left s -> mapM_ putStrLn s
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Right b -> putStrLn $ show (b a :: Integer) -- now apply it
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{-
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-- should work, but doesn't. type check fails
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-- (due to static vs dynamic typing issue)
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m_b <- unsafeEval_ "\\dyn -> fromMaybe (7 :: Int) (fromDynamic dyn)"
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["Data.Dynamic","Data.Maybe"] [] []
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-}
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