[racket users] struct #:methods question

[Kevin Forchione]

Hi guys,
How do you return an instance of the structure type from the struct’s #:methods? This is would seem to be a common situation, but it has me stumped.

Kevin

[Jon Zeppieri]

There's no trick to it:

#lang racket/base

(require racket/generic)

(define-generics foo
(foo-do foo x))

(struct thing (x)
#:methods gen:foo
[(define (foo-do f x)
(thing x))])

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[David Storrs]

On Mon, Apr 20, 2020 at 6:50 PM Jon Zeppieri <zepp...@gmail.com> wrote:

There's no trick to it:

#lang racket/base

(require racket/generic)

(define-generics foo
  (foo-do foo x))

(struct thing (x)
  #:methods gen:foo
  [(define (foo-do f x)
     (thing x))])


On Mon, Apr 20, 2020 at 6:32 PM Kevin Forchione <lys...@gmail.com> wrote:
>
> Hi guys,
> How do you return an instance of the structure type from the struct’s #:methods? This is would seem to be a common situation, but it has me stumped.
>
> Kevin

<self-promotion>

Note that if you're getting fancy with structs then you might want to check out: https://docs.racket-lang.org/struct-plus-plus/index.html

Among other things, it auto-generates functional setters and functional updaters, a keyword constructor, dotted accessors, reflection data, and allows for contracts on individual fields and enforcement of relationships between fields. 

</self-promotion>

>
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