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fancify the patterns in book-club

This commit is contained in:
Sam Caldwell 2019-05-24 11:12:53 -04:00
parent 22a228ab4b
commit c78b76b38c
1 changed files with 7 additions and 7 deletions
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14
racket/typed/examples/roles/book-club.rkt
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@ -67,7 +67,7 @@
(field [books Inventory inventory])
;; Give quotes to interested parties.
(during (observe (book-quote (bind title String) discard))
(during (observe (book-quote $title _))
;; TODO - lookup
(assert (book-quote title (lookup title (ref books)))))))))
@ -116,10 +116,10 @@
(set! book-list (rest (ref book-list)))]))
;; keep track of book club members
(define/query-set members (club-member (bind name String)) name
(define/query-set members (club-member $name) name
#;#:on-add #;(printf "leader acknowledges member ~a\n" name))
(on (asserted (book-quote (ref title) (bind quantity Int)))
(on (asserted (book-quote (ref title) $quantity))
(printf "leader learns that there are ~a copies of ~a\n" quantity (ref title))
(cond
[(< quantity (+ 1 (set-count (ref members))))
@ -128,9 +128,9 @@
[#t
;; find out if at least half of the members want to read the book
(start-facet poll-members
(define/query-set yays (book-interest (ref title) (bind name String) #t) name)
(define/query-set nays (book-interest (ref title) (bind name String) #f) name)
(on (asserted (book-interest (ref title) (bind name String) discard))
(define/query-set yays (book-interest (ref title) $name #t) name)
(define/query-set nays (book-interest (ref title) $name #f) name)
(on (asserted (book-interest (ref title) $name _))
;; count the leader as a 'yay'
(when (>= (set-count (ref yays))
(/ (set-count (ref members)) 2))
@ -172,7 +172,7 @@
;; assert our presence
(assert (club-member name))
;; respond to polls
(during (observe (book-interest (bind title String) discard discard))
(during (observe (book-interest $title _ _))
(define answer (member? title titles))
(printf "~a responds to suggested book ~a: ~a\n" name title answer)
(assert (book-interest title name answer)))))))