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David Van Horn wrote:
I agree that this SRFIs current optional arguments specification is cognitively cumbersome.
Because of the (=? cmp)-short cut?
Beyond the cognitive burden, it also makes static analysis of code
> very difficult. Why is that?
I also agree comparisons should be the first argument (if used), and I'm not averse to requiring the compare procedure, but I realize it's verbose.Would the following work as a reasonable compromise?
procedure: ((=? [ compare ]) x y )
This has the added benefit(?) that you can now drop `?' since =, <, >, <=, >= are not defined on 0 or 1 arguments, thus:(= 1 2) ;; performs a test with R5RS semantics. ((=) 1 2) ;; performs a test with SRFI-67 semantics.
This costs an extra function application per comparision. Personally, I'd rather remove the (=? cmp) short cut than pay an extra cost per comparison. The only situation in which I would specialize =? with respect to a fixed comparion function, is when the specialized comparison is used twice or more. In that situation a LET is needed, so whether I have to write (let ([my=? (=? my-cmp)]) ... (my=? a b) ... ... (my=? c d) ...) or (let ([my=? (cut =? my-cmp <> <>)]) ... (my=? a b) ... ... (my=? c d) ...) isn't terribly important to me. -- Jens Axel Søgaard