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440 pages, Paperback
Published February 21, 2023
> 0
0
> (zero? 0)
#t
> (- 3 (+ 1 2))
0
> (zero? (- 3 (+ 1 2)))
. . zero?: contract violation
expected: number?
given: 0
> (= 0 (- 3 (+ 1 2)))
#t
(require (planet williams/describe/describe))
> (describe 0)
0 is a byte (i.e., an exact positive integer fixnum between 0 and 255 inclusive) zero
> (describe (- 3 (+ 1 2)))
#(#[procedure:dual] 0 #[procedure:...utodiff/B-prims.rkt:20:10]) is a mutable vector of length 3