The disadvantage of purity

[berni44]

On Sunday, 29 December 2019 at 10:46:07 UTC, Dominikus Dittes 
Scherkl wrote:
> This should indeed be NOT the same parameters. There should be 
> a hidden additional parameter (lets name it "called_internal"), 
> that be false in the original call and true in a recursion. 
> With this it's perfectly pure while returning something 
> different if called by itself.

Thanks for your ideas, but unfortunately I think these cannot be 
used here. The reason is, that I have no control over the 
intermediate steps, so I cannot pass that additional parameter 
(ref State s in sarn's code). These intermediate steps consist of 
calls to toString, which then do, whatever the user want's them 
to do, and eventually call format again and format calls 
formatObject with identical parameters. I can't change the 
signature of toString, nor make the users implement that...