It looks like you copied the code incorrectly: it should be (module adapter racket ...), but you have (module adapter racket/stream ...).
To get the special performance you are referring to, you don't want to make a structure that's a sequence: you need to use `define-sequence-syntax` with `:do-in` ( http://docs.racket-lang.org/reference/for.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define-sequence-syntax))). I believe this should work with Typed Racket, but I haven't tried it. -Philip On Mon, Apr 23, 2018 at 3:00 PM, HiPhish <hiph...@openmailbox.org> wrote: > The adapter submodule does not work, I get the following error (in both > typed and untyped Racket): > > fib.rkt:9:0: module: no #%module-begin binding in the module's language > in: (module adapter racket/stream (provide stream-first stream-rest > (rename-out (stream-cons* stream-cons))) (define (stream-cons* make-first > make-rest/seq) (stream-cons (make-first) (sequence->stream > (make-rest/seq))))) > > If I understand your code correctly, the idea is to define `fibonacci` as > a stream which returns a stream of Fibonacci numbers, correct? Won't that > incur a performance loss when used like that in a for-loop if the user does > not wrap it up in `in-stream`? The idea of `in-fibonacci` was to have a > form which can be used in a foor-loop the same way `in-naturals` can be. > Except `in-fibonacci` would have an optional argument at which Fibonacci > number to start counting. > > > On Sunday, April 22, 2018 at 10:48:12 AM UTC+2, Philip McGrath wrote: >> >> I hope there's a better way, but this works. The adapter submodule is >> needed because the normal `stream-cons` is a macro that expands into some >> private things that don't have types, and it requires that the rest >> expression produce a stream, not just any sequence. Note also, if you >> haven't worked with `racket/stream` before, that the arguments to the >> normal `stream-cons` are evaluated lazily. >> > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
