[Haskell-cafe] Understanding tail recursion and trees

[Miguel Mitrofanov]

Copy-paste approach's failed you. Hint: try removing acountL  
definition and compiling everything else.

>> -- count with tail calls for the left subtree 
>> acountL :: Tree -> Integer -> Integer
>> acountL (Leaf _)       acc = acc + 1
>> acountL (Branch t1 t2) acc = acountL t1 $! (acountL t2 acc)
>>
>>
>> -- count with tail calls for the right subtree 
>> acountR :: Tree -> Integer -> Integer
>> acountR (Leaf _)       acc = acc + 1
>> acountR (Branch t1 t2) acc = acountR t2 $! (acountL t1 acc)
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