diff options
| -rw-r--r-- | testsuite/tests/typecheck/should_run/tcrun044.hs | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/testsuite/tests/typecheck/should_run/tcrun044.hs b/testsuite/tests/typecheck/should_run/tcrun044.hs index 0a2413c928..031cd40bde 100644 --- a/testsuite/tests/typecheck/should_run/tcrun044.hs +++ b/testsuite/tests/typecheck/should_run/tcrun044.hs @@ -2,31 +2,26 @@ import qualified Data.Set as S --- You can't write this as an associated type synonym --- because it is indexed in more arguments than those --- bound by the class --- --- A better solution would be index it only in "m" --- but then how do we write the instance for []? -type family RMonadCtxt m a :: Constraint - class RMonad m where + type RMonadCtxt m a :: Constraint returnR :: (RMonadCtxt m a) => a -> m a bindR :: (RMonadCtxt m a, RMonadCtxt m b) => m a -> (a -> m b) -> m b -type instance RMonadCtxt [] a = () instance RMonad [] where + type RMonadCtxt [] a = () returnR x = [x] bindR = flip concatMap -type instance RMonadCtxt S.Set a = Ord a instance RMonad S.Set where + type RMonadCtxt S.Set a = Ord a returnR x = S.singleton x bindR mx fxmy = S.fromList [y | x <- S.toList mx, y <- S.toList (fxmy x)] main = do - print $ (returnR 1 ++ returnR 2) `bindR` (\x -> returnR (x + 1) ++ returnR (x + 2)) - print $ (returnR 1 `S.union` returnR 2) `bindR` (\x -> returnR (x + 1) `S.union` returnR (x + 2)) + print $ (returnR 1 ++ returnR 2) `bindR` + (\x -> returnR (x + 1) ++ returnR (x + 2)) + print $ (returnR 1 `S.union` returnR 2) `bindR` + (\x -> returnR (x + 1) `S.union` returnR (x + 2)) |