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>> It would be useful to define eq?, eqv? and equal? on boxes. (F/X: Can >> of worms being opened.) > > The definition of eqv? in RnRS covers them well enough: they are eqv? if > the are the product of the same call to `box`, otherwise not. `Eq?` and > `equal?` by their definitions must agree with `eqv?`. If boxes are records, then eqv? behaves in this way, although eq? and equal? are not necessarily identical to eqv?. However, unless I am missing something, the SRFI does not require boxes to be records. Defining equal? on boxes to be more like equal? on vectors of length 1 would be more useful, I think. That is, if boxes are records, then (equal? (box 0) (box 0)) need not return #t. I would prefer that it was required to return #t. Regards, Alan