Hello everyone,
I have a question about creating a steam that yields multiple values on
each iteration. Given something like:
(require racket/strema)
(define my-stream (for/stream ([i (in-range 1 10)])
(values "hi" i)))
When I'm trying to:
(let-values ([(a b) (stream-ref my-stream 0)])
(printf "~v: ~v" a b))
I'm getting:
; result arity mismatch;
; expected number of values not received
; expected: 1
; received: 2
; values...:
; "hi"
; 2
; Context:
;
/nix/store/z4mpvw1p6whq454lmjshbdr6472sdbr3-racket-7.6/share/racket/collects/racket/repl.rkt:11:26
Similarly:
(for ([(a b) my-stream])
(printf "~v: ~v" a b))
leads to:
; result arity mismatch;
; expected number of values not received
; expected: 1
; received: 2
; values...:
; "hi"
; 1
; Context:
; tcp-accepted:1:1 for-loop
; top-level:1:1 [running body]
;
/nix/store/z4mpvw1p6whq454lmjshbdr6472sdbr3-racket-7.6/share/racket/collects/racket/repl.rkt:11:26
Documentation on stream-ref specifically mentions that it can have
multiple values:
https://docs.racket-lang.org/reference/streams.html?q=stream-ref#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-ref%29%29
What am I doing wrong here?
P.S. The context is that I'm trying to create a function that would
return results from an API as a stream that can be iterated with the for
family of forms, and would yield multiple values per iteration.
--
Yury Bulka
https://mamot.fr/@setthemfree
#NotOnFacebook
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