class - Haskell monoid foldable rose tree -

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I need to create an alliance frequency for the data structure of the rose tree: 
  Data rose a = a: & gt; [Daily A] Deriving (eq, show)   
 with the following monoides and rosary-related classes / instances:  
  Example factor everyday where fmap f ( A: & gt; BS) = (FA): & gt; (Map (FMAP F) BS) Class Monoid A where Mempati :: A (<> :: A -> A - & gt; An example monoid [a] where mempty = [] (  
 Whatever I tried:  
  Example Foldable Rose where fold (A:> B) = a  & Gt; (FoldMapMap b)   
 Although this is not working properly, I get an error to check the system:  
  *** Fail! Exception: 'Prelude. Delayed ': []: & gt; []   
 But I'm not sure why this does not work, can someone help me?  
 Thanks in advance!  
 Best Regards, Skyfather   
 
 
 Your implementation of  fold  was right, there is no reason to change it.  
 The problem is that it is not enough to define  fold   Foldable   
  
 < / p> 
  
  
  
   square foldable where the source   
 Data structures can be combined.  
 Code> Folder Map  or  foldr .   
 Then you should define either  foldMap  or  foldr  (or both). Defining  foldMap  is easier and more natural (and in many cases even more effective). Then you should write something:  
  Import data. Falthal import data Monod Data Daily A = A: & gt; [Rose A] deriving (one, show) instance fondable rose, where Foldmap F (X: & gt; xs) = FX and LT; & Gt; Folder Map (Folder f) X

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