> (delay (+ 5 10))
#<promise>
> (define p (delay (+ 5 10)))
> p
#<promise>
> p
#<promise>
> (force p)
15
> (define p (delay (/ 5 0)))
> p
#<promise>
> (force p)
[image] [image] /: division by zero
> (define p (delay (+ x 7)))
> (force p)
[image] [image] x: undefined;
 cannot reference an identifier before its definition
> (define x 8)
> (force p)
15
> (define bigpromise (fact 10000))
> (force bigpromise)
[image] [image] force: expected argument of type <promise>; given: 2846259680917054518906413212119868890148051401702799230794179994274411340003764443772990786757784775815884062142317528830042339940153518739052421161382716174819824199827592418289259787898124253120594659962598670656016157203603239792632873671705574...
> (define bigpromise (fact 10000))
> (define bigpromise (delay (fact 30000)))
> bigpromise
#<promise>
> (force bigpromise)
275953724621938459937994216642546278398076204452933098552963503680007586885036056583297297765120425434165030630836918010572007988921117364762399843338313718496725428585731122241126651370462320856666351384397125584539........0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
> (define bigpromise (delay (fact 30000)))
> (* 0 (force bigpromise))
0