[andreasvc]

I think it is more instructive to realize that certain (most?) problems rely on conditionals conceptually. You could then work around them by effectively implementing conditionals anew and spreading code over smaller functions, but the algorithm is still conditional in nature. I am also curious about the relation of conditionals to other constructs. Is the for loop disallowed because it checks for the end of the loop? But it could be implemented with a map over a range, which does no such check (assuming range is a primitive operation). In this way conditionals can be eliminated by recruiting a variety of possible constructs, but it all depends on the rules you're setting.