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Diffstat (limited to 'Haskell-book/15/semigroup/app/Main.hs')
| -rw-r--r-- | Haskell-book/15/semigroup/app/Main.hs | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Haskell-book/15/semigroup/app/Main.hs b/Haskell-book/15/semigroup/app/Main.hs new file mode 100644 index 0000000..237aefe --- /dev/null +++ b/Haskell-book/15/semigroup/app/Main.hs @@ -0,0 +1,18 @@ +module Main where + +import Data.Monoid +import Mem + +f' :: Num a => Mem a String +f' = Mem $ \s -> ("hi", s + 1) + +main :: IO () +main = do + let rmzero = runMem mempty 0 + rmleft = runMem (f' <> mempty) 0 + rmright = runMem (mempty <> f') 0 + print $ (rmleft :: (String, Int)) + print $ (rmright :: (String, Int)) + print $ (rmzero :: (String, Int)) + print $ rmleft == runMem f' 0 + print $ rmright == runMem f' 0 |