On Sat, Mar 29, 2008 at 10:18:53PM -0400, Mark J. Reed wrote: : In general, is : : [op] (p1,p2,p3,p4...) : : expected to return the same result as : : p1 op p2 op p3 op p4... : : including precedence considerations? : : That is, should : : [**](2,3,4) : : return 2^(3^4)=2^81, or (2^3)^4 = 4096?
Yes, in fact the section on Reduction Operators uses exponentiation obliquely in one of its examples of something that should work right-to-left. Admittedly it's not clearly stated there... But the basic idea is always that the reduction form should produce the same result as if you'd written it out with interspersed infixes. It's a linguistic construct, not a functional programming construct. It's not intended to be in the same league as foldl and foldr, and is only just slightly beyond a macro insofar as it can intersperse however many operators it needs to for an arbitrarily sized list. It's not making any attempt to deal with anonymous first-class functions though. Call a real function for that. :) Larry
