I’ve been having problems with but-not/e, and I’ve been bouncing between
strange things, but this one really looks ilke a bug. Unless it’s not.
John
#lang racket
(require data/enumerate
data/enumerate/lib)
(define (even-mod-10? x) (= 0 (modulo x 10)))
(define tens/e
(map/e (λ (x) (* x 10))
(λ (x) (/ x 10))
natural/e
#:contract (and/c natural?
even-mod-10?)))
(define test/e (but-not/e tens/e (range/e 1000 2000)))
(enum->list test/e 10)
(to-nat test/e 10)
;; produces:
map/e: broke its own contract
promised: even-mod-10?
produced: 1001
in: an and/c case of
the 1st argument of
the out argument of
(->i
((in
(e es c)
(cond
((null? es) (-> (enum-contract e) c))
(else
(dynamic->*
#:mandatory-domain-contracts
(map enum-contract ...)
#:range-contracts
(list c)))))
(out
(e es c)
(cond
((null? es) (-> c (enum-contract e)))
(else
(dynamic->*
#:mandatory-domain-contracts
(list c)
#:range-contracts
(map enum-contract ...)))))
(e enum?)
#:contract
(c contract?))
#:rest
(es (listof enum?))
#:pre/desc
(in out e es)
(appears-to-be-a-bijection?
in
out
(cons e es))
(result enum?))
contract from:
<pkgs>/data-enumerate-lib/data/enumerate.rkt
blaming: <pkgs>/data-enumerate-lib/data/enumerate.rkt
(assuming the contract is correct)
at: <pkgs>/data-enumerate-lib/data/enumerate.rkt:45.3
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