2005-05-15 06:03:55 +00:00

43 lines
1.1 KiB
Haskell

{-# OPTIONS -cpp #-}
--
-- Should evaluate to '3', unless something goes wrong.
--
-- Not so bad to use AltData, as it is already derived for all the basic
-- types. Then, just replace deriving Typeable, with hand-derived
-- instance of Typeable (see hs-plugins/examples/eval/eval_fn1/Poly.hs
--
--
#include "../../../config.h"
import System.Eval.Haskell
import AltData.Dynamic
-- import Data.Dynamic
pkgconf = TOP ++ "/plugins.conf.inplace"
main = do
a <- return $ toDyn (3::Int)
m_b <- unsafeEval_ "\\dyn -> fromMaybe (7 :: Int) (fromDyn dyn)"
["AltData.Dynamic","Data.Maybe"] -- imports
[ "-package-conf "++pkgconf , "-package altdata" ]
[ pkgconf ]
[]
{-
-- should work, but doesn't. type check fails
-- (due to static vs dynamic typing issue)
m_b <- unsafeEval_ "\\dyn -> fromMaybe (7 :: Int) (fromDynamic dyn)"
["Data.Dynamic","Data.Maybe"] [] []
-}
case m_b of
Left s -> mapM_ putStrLn s
Right b -> putStrLn $ show (b a :: Int)