This is a comment about http://trac.sacrideo.us/wg/wiki/ComparatorsCowan
I noticed some issues and should like to make comments about this possible SRFI/module. General Issues: It is my personal opinion that this module should be helpful to anyone involved in either total orders or partial orders, such as floating-point numbers (which form a total order if you ignore NaNs and -0.0). One way of doing this would be to use an exception/condition to express a lack of total order, another would be to return something other than -1, 0, 1 from the compare procedure (perhaps return +nan.0), which would violate the conditions for a compare procedure according to this module as specified so far. I'm not sure what the best way to do this is, except to provide additional procedures for floating-point numbers, and not handle partial orders in a general way. My intuition tells me that a general approach would be more valuable in the long term, than to special case floats. Treating any and all partial orders that come along as special cases, just seems wrong to me. Issues with "Comparison syntax": (if3) and (if**?) don't have a comparator parameter! Issues with "Comparison procedures": The (not=?) procedure should be removed, there is a long history of omitting it. All (**?) procedures should be removed. All (chain**?) procedures should be renamed to (**?). All (**?) procedures: [(<?), (<=?), (=?), (>?), (>=?)] should have 2 or more parameters, as (chain**?) does now. All (**/**?) procedures: [(</<=?), (>/>=?), (<=/<?), (>=/>?)] should have exactly 4 parameters, as they do now. The (</<?) procedure should be removed, it is the same as the new (<?). The (<=/<=?) procedure should be removed, it is the same as the new (<=?). The (>/>?) procedure should be removed, it is the same as the new (>?). The (>=/>=?) procedure should be removed, it is the same as the new (>=?).
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