Hi,
I'm trying to go from a small racket program that uses classes to a typed
racket version of the program, but I can't find a combination of types that
works. (The untyped version works as intended.)
Specifically, if I have a recipe% class, and an amount-mixin and unit-mixin ,
and each of these 3 have 1-argument init specifiers, how do I add types to
both mixins such that (amount-mixin (unit-mixin recipe%)) works? (edited)
The untyped version:
#lang racket/base
(require racket/class)
(define recipe%
(class object%
(init name #;steps )
(super-new)
(define _name name)
;(define _steps steps)
;(define/public (get-steps) _steps)
(define/public (get-name) _name)))
(define (amount-mixin %)
(class %
(init amount)
(define _amount amount)
(super-new)
(inherit get-name)
(define/public (get-amount) _amount)))
(define (unit-mixin %)
(class %
(init unit)
(define _unit unit)
(super-new)
(inherit get-name)
(define/public (get-unit) _unit)))
(unit-mixin (amount-mixin recipe%))
And the typed version (that raises an error):
#lang typed/racket/base
(require typed/racket/class)
(define-type recipe<%>
(Class (init [name String])
(get-name (-> String))))
(: recipe% recipe<%>)
(define recipe%
(class object%
(init [name : String])
(super-new)
(: _name String)
(define _name name)
(define/public (get-name) _name)))
(: amount-mixin (-> recipe<%>
(Class #:implements recipe<%>
(init [amount Number]
[name String])
(get-amount (-> Number)))))
(define (amount-mixin %)
(class %
(init [amount : Number])
(: _amount Number)
(define _amount amount)
(super-new)
(inherit get-name)
(define/public (get-amount) _amount)))
(: unit-mixin (-> recipe<%> (Class #:implements recipe<%>
(init [unit String]
[name String])
(get-unit (-> String)))))
(define (unit-mixin %)
(class %
(init [unit : String])
(: _unit String)
(define _unit unit)
(super-new)
(inherit get-name)
(define/public (get-unit) _unit)))
(unit-mixin (amount-mixin recipe%))
Any advice on how to make this work? Or whether to simply not do this in
typed racket?
Regards,
Hashim.
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