[Haskell-cafe] monad example

[Damien Mattei]

  hello,
i still seaching a good monad example and after passed the classic
tutorial about Maybe monad or State monad which is found in almost 90%
of the litterature i try to learn in deep the example of monad that
talk about probability (
http://learnyouahaskell.com/for-a-few-monads-more )
for this i try to trace the calls of the inner monad definition like in
the file, i give the file in attachment (monade.hs) and the output has
a lot of garbage data, not the nicer way to display it,sorry.

What i can not figure out is at what stage the program construct the

[Tails,Heads] , [Heads,Heads] ... etc

i do not know,
 if someone could explain me in detail the action of

a <- coin
b <- loadedCoin
return [a,b]

step by step it would be of great help...

Regards,
Damien

note:
here is the ouput:

*Main> :load monade.hs
[1 of 1] Compiling Main             ( monade.hs, interpreted )
Ok, one module loaded.
*Main> flipTwoVal
Prob {getProb =  (Monad Prob >>=
 flatten
  (fmap f m)
  Functor Prob
      Functor Prob (f x,1 % 2)
   flatten multAll map ... p= 1 % 2
 (Monad Prob >>=
 flatten
  (fmap f m)
  Functor Prob
      Functor Prob (f x,1 % 10)
   flatten multAll map ... p= 1 % 10
 Monad Prob return)
[       flatten multAll (1 % 10*1 % 1)
       flatten multAll (1 % 2*1 % 10)
([Heads,Heads],1 % 20)      Functor Prob (f x,9 % 10)
   flatten multAll map ... p= 9 % 10
 Monad Prob return)
,       flatten multAll (9 % 10*1 % 1)
       flatten multAll (1 % 2*9 % 10)
([Heads,Tails],9 % 20)      Functor Prob (f x,1 % 2)
   flatten multAll map ... p= 1 % 2
 (Monad Prob >>=
 flatten
  (fmap f m)
  Functor Prob
      Functor Prob (f x,1 % 10)
   flatten multAll map ... p= 1 % 10
 Monad Prob return)
,       flatten multAll (1 % 10*1 % 1)
       flatten multAll (1 % 2*1 % 10)
([Tails,Heads],1 % 20)      Functor Prob (f x,9 % 10)
   flatten multAll map ... p= 9 % 10
 Monad Prob return)
,       flatten multAll (9 % 10*1 % 1)
       flatten multAll (1 % 2*9 % 10)
([Tails,Tails],9 % 20)]}
*Main> flipTwoVal
Prob {getProb = [([Heads,Heads],1 % 20),([Heads,Tails],9 %
20),([Tails,Heads],1 % 20),([Tails,Tails],9 % 20)]}
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