collect multiple values at once

[dedbox]

Sometimes I just want to flatten N values into a single list and buffer any overflow for the next synchronization.

Currently throws an exception when given multiple values at once:

main.rkt> (define m (make-mediator))
main.rkt> (thread (λ () (for ([i 10]) (sync (say m i #t)))))
#<thread>
main.rkt> (sync (collect m 4))
; cons: arity mismatch;
;  the expected number of arguments does not match the given number
;   expected: 2
;   given: 3
;   arguments...:
;    3
;    #t
;    '()

[dedbox]

Another alternative: any number of values from N senders.

> (sync (collect* m 4))
'((1 2) () (3) (4 5 6))

This could be used to implement the current behavior by checking each sub-list has length 1 and flattening the results.

There are a lot more variations:

• overflow: drop vs error, report vs silent
• sync: release senders immediately (collect) or all at once (quorum)?