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The towers of Hanoi - classic recursion example

See en.wikipedia.org/wiki/Tower_of_Hanoi for a detailed intro, if you're not familiar with this classic recurrence problem.

Good example

Set the towers as variables, ahead of calling the function, in the global context:

send::  msg ctx.set  (state :JSON)

Now call the recursion:

send::  msg sample.hanoi  (disk:Number=3, source="a", dest="b", aux="c")

send::  msg ctx.echo  (m)

expect::  (state[="a"] is [4,5])
expect::  (state[="b"] is [0,1,2,3])

Bad example:

This simplistic example would not work, because the parameters are immutable. To be able to mutate the contents of the incoming arguments, you'll need a global scope like we used in the "good" example above, with ctx.set.

send::  msg sample.hanoi.bad  (disk:Number=3, source :Array=[..], dest :Array=[..], aux :Array=[..])

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