<HTML><BODY>Recommended way for mutual dependencies is to use units: <a href="http://docs.racket-lang.org/guide/units.html">http://docs.racket-lang.org/guide/units.html</a> You may define struct accessors as unit exports/imports and then link them Mon, 18 Aug 2014 23:44:11 -0400 от Jon Zeppieri <zeppieri@gmail.com>: <blockquote style="border-left:1px solid #0857A6; margin:10px; padding:0 0 0 10px;"> <div id=""> <div class="js-helper js-readmsg-msg"> <style type="text/css"></style> <div> <base target="_self" href="https://e.mail.ru/"> <div id="style_14084204110000000703_BODY">Say I want to do basically the following, except with larger, more complicated generic interfaces: ```racket #lang racket/base (require racket/generic) (define-generics ->foo-provider (->foo ->foo-provider)) (define-generics ->bar-provider (->bar ->bar-provider)) (struct foo (x) #:methods gen:->foo-provider [(define (->foo f) f)] #:methods gen:->bar-provider [(define (->bar f) (bar (foo-x f)))]) (struct bar (x) #:methods gen:->foo-provider [(define (->foo b) (foo (bar-x b)))] #:methods gen:->bar-provider [(define (->bar b) b)]) ``` That is, I want to have struct types that can use generic methods to construct instances of one another. Since the actual struct types are rather more complicated than this example, I'd really like to split up their implementations into separate modules. If I weren't using generics, this would be straightforward; I'd put the struct type definitions themselves in a module, or set of modules, and I'd put the operations in modules specific to their respective struct types. The modules containing the operations would be able to require all of the struct type definitions, so they could freely construct instances of one another. In the present case, however, the method implementations need to be defined along with the struct type definition. I can't do something like: ``` [(define ->foo bar->foo)] ``` ... where bar->foo comes from a bar-specific module, because that would lead to a circular dependency (bar->foo needs the foo constructor, which is defined in this module, while this module needs bar->foo). I could work around this with mutable bindings (either at the module level or, better, in method dispatch), but I'm not fond of either approach. With the right structure inspector maybe (?) it would be possible to modify whatever dispatch table is actually used, but that sounds hairy. I guess I'm wondering if some other trick is possible here. -Jon ____________________ Racket Users list: <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> </div> <base target="_self" href="https://e.mail.ru/"> </div> </div> </div> </blockquote> -- Roman Klochkov </BODY></HTML>