This page is part of the web mail archives of SRFI 114 from before July 7th, 2015. The new archives for SRFI 114 contain all messages, not just those from before July 7th, 2015.
On 12/08/2013 09:01 AM, John Cowan wrote: > Kevin Wortman scripsit: > >> Returning the first tied argument seems like it would be a little more >> straightforward to implement, at least to me. But I'm comfortable with >> the current behavior. I don't think it matters much as long as the >> behavior is documented. > > Here's the current sample implementation (note that it depends on `apply` > calling its argument tail-recursively): > > (define comparator-min > (case-lambda > ((comparator a) > a) > ((comparator a b) > (if (<? comparator a b) a b)) > ((comparator a b . objs) > (comparator-min comparator a (apply comparator-min comparator b objs))))) > > (define comparator-max > (case-lambda > ((comparator a) > a) > ((comparator a b) > (if (>? comparator a b) a b)) > ((comparator a b . objs) > (comparator-max comparator a (apply comparator-max comparator b objs))))) > > Exactly what you get depends on which predicate you use, of course. Gotcha. I was thinking of the algorithm: scan each element and keep track of the smallest (resp. largest) element you've seen so far. Something like (untested): (define (comparator-min comparator first . rest) (fold (lambda (x least) (if (<? comparator x least) x least)) first rest)) Kevin Wortman