boot2

Playing with the boostrap
git clone https://git.ryansepassi.com/git/boot2.git
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037-record-predicate.scm (432B)

      1 ; Predicates distinguish disjoint record types; rejects non-records too.
      2 (define-record-type point (make-point x y) point? (x point-x) (y point-y))
      3 (define-record-type box   (make-box w)     box?   (w box-w))
      4 
      5 (define p (make-point 1 2))
      6 (define b (make-box 99))
      7 (sys-exit (cond ((point? b)   1)
      8                 ((box? p)     2)
      9                 ((point? '()) 3)
     10                 ((point? p)   22)
     11                 (else         99)))