<div dir="ltr"><div>Problem 1 -- you have to use define/generic if you want to use the generic version of something in the context of a set of specific method implementations. That's by design. </div>Problem 2 -- what error message or unexpected behavior are you getting? That should work, it sounds like a bug in define/generic if it's not working. </div><div class="gmail_extra"> <div>Carl Eastlund</div> <div class="gmail_quote">On Fri, Aug 16, 2013 at 4:36 PM, J. Ian Johnson <<a href="mailto:ianj@ccs.neu.edu" target="_blank">ianj@ccs.neu.edu</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> I'm starting to use generics, and me being myself, I wrote some macros to make writing method definitions easier. But, I'm seeing that #:methods seems to rebind method identifiers in a way that hygiene interferes with. I would expect to be allowed to do the following two things (problems annotated): (struct exp (label fvs-box)) ;; parent struct for all expressions (define-generics binds-variables [free-box binds-variables] [free binds-variables #:bound [bound]] #:fallbacks [(define (free e #:bound [bound ∅]) ∅) (define free-box exp-fvs-box)] #:fast-defaults ([(compose unbox free-box) (define (free e #:bound bound) (unbox (free-box e)))])) ;; problem 1: free-box not in scope (define-syntax-rule (def-free e gfree bound struct [(pats ...) rhss ...]) (begin (define/generic gfree free) ;; problem 2: since #:methods rebinds free, this is not in the scope one would expect with its definition in the define-generics form. (define (free e #:bound [bound ∅]) (match e [(struct _ fvs-box pats ...) (set-box! fvs-box (let () rhss ...))])))) (struct var exp (name) #:transparent #:methods gen:binds-variables [(def-free e gfree bound var [(x) (if (x . ∈ . bound) ∅ (set x))])]) I have workarounds thanks to stamourv, but they're unpleasant: Problem 1: define free in fast-defaults as an eta-expansion of a definition outside the define-generics form that does what you want. Problem 2: add free as a parameter to def-free, and pass free in at all uses of def-free. The first problem seems like more of a programming error than the use of the wrong tool. The second problem seems like generic method identifiers should be syntax-parameters, if they indeed need to be rebound in the rhs of the #:methods argument. Are these expectations unreasonable/against the design decisions for generics? Thanks, -Ian _________________________ Racket Developers list: <a href="http://lists.racket-lang.org/dev" target="_blank">http://lists.racket-lang.org/dev</a> </blockquote></div> </div>