On 12-3-2009 15:22, Invisible wrote:
> OK, so does anybody know the trick to taking a parse tree such as
> 
>   (2*(5^2))+((8*6)^(x-1)))
> 
> and printing it out *without* several billion brackets?
> 
> Printing it with brackets as above, or with no brackets at all, is quite 
> trivial:
> 
>   output expr = case expr of
>     Operator n x y = "(" ++ output x ++ n ++ output y ++ ")"
>     Variable n     = n
>     Constant v     = show v
>     ...
> 
> But how do you "decide" when the brackets can or can't be omitted?

Why not in (reverse) polish, no brackets at all

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