(sorry for the typos - obviously, it should be racket/stream)

--
Yury Bulka
https://mamot.fr/@setthemfree
#NotOnFacebook



Yury Bulka <setthemf...@privacyrequired.com> writes:

> 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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