fork download 
  1. import Data.Monoid
  2. import Data.Functor
  3. import Control.Applicative
  4.  
  5. newtype NT m a = NT (m a) deriving (Eq,Show)
  6.  
  7. instance (Monoid a, Applicative m) => Monoid (NT m a) where
  8.     mempty = NT $ pure mempty
  9.     mappend (NT a) (NT b) = NT $ mappend <$> a <*> b
  10.  
  11. main = do
  12.     print $ (NT (Just "a") <>  NT (Just "b")) <> NT (Just "c")
  13.     print $  NT (Just "a") <> (NT (Just "b")  <> NT (Just "c"))
  14.     print $ (NT ["a"] <>  NT ["b"]) <> NT ["c"]
  15.     print $  NT ["a"] <> (NT ["b"]  <> NT ["c"])
  16.     print $ (NT (Just $ NT ["a"]) <>  NT (Just $ NT ["b"])) <> NT (Just $ NT ["c"])
  17.     print $  NT (Just $ NT ["a"]) <> (NT (Just $ NT ["b"])  <> NT (Just $ NT ["c"]))
  18.  
Success #stdin #stdout 0s 4704KB
comments (?)
stdin 
Standard input is empty
stdout 
NT (Just "abc")
NT (Just "abc")
NT ["abc"]
NT ["abc"]
NT (Just (NT ["abc"]))
NT (Just (NT ["abc"]))
https://ideone.com/OXkl6d
language:
Haskell (ghc 8.4.4)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!