Clean way to implement a list of checkboxes?

[cloudrac3r]

Clean way to implement a list of checkboxes?

[Bogdanp]

Re. your first example, I would extract helper functions to help reduce the indentation:

#lang racket/gui/easy

(require racket/dict
         racket/function)

(struct food^ (name checked?) #:transparent)

(define (set-food^-checked? f checked?)
  (struct-copy food^ f [checked? checked?]))

(define (update-food foods k checked?)
  (dict-update foods k (curryr set-food^-checked? checked?)))

(define/obs @foods
  `((1 . ,(food^ "Apple" #t))
    (2 . ,(food^ "Banana" #f))
    (3 . ,(food^ "Broccoli" #f))
    (4 . ,(food^ "Ice Cream" #t))))
(obs-observe! @foods println)

(render
 (window
  #:size '(250 250)
  (list-view
   @foods
   #:key car
   (λ (k @id+food)
     (define @food (@id+food . ~> . cdr))
     (checkbox
      #:label (@food . ~> . food^-name)
      #:checked? (@food . ~> . food^-checked?)
      (λ (checked?)
        (@foods . <~ . (curryr update-food k checked?))))))))

Re. the match idea: I can't think of a way to write a match expander that produces derived observables, so I don't think that can work with regular match. I don't have any better ideas about how to further improve this code at the moment, either.

[cloudrac3r]

Thanks for the reply! You're right, extracting those food operations to functions does make it easier to read and write the code. In the future, I might play around with making a limited version of list-view/match which just covers unpacking lists and structs, since those are the only data types I've found myself using in list-views.