[CM] Would you like to use define-case-class?

[Da Shen]

I was a Scala programmer before. In Scala, case class is widely adopted for data processing.
I just implemented the equiv of case class in Goldfish Scheme and packaged it in the (liii case) R7RS library:
https://github.com/LiiiLabs/goldfish/blob/main/goldfish/liii/case.scm <https://github.com/LiiiLabs/goldfish/blob/main/goldfish/liii/case.scm >
Here are sample usages of define-case-class.
Sample code 1: simplest use case
----------------------------------------------------------
(define-case-class person
 ((name string? "Bob")
 (age integer?)))
(let1 bob (person :name "Bob" :age 21)
 (check (bob 'name) => "Bob")
 (check (bob 'age) => 21)
 (check ((bob :name "hello") 'name) => "hello")
 (check-catch 'value-error (bob 'sex))
 (check-true (person? bob)))
(check-true (person=? (person "Bob" 21) (person "Bob" 21)))
(check-false (person=? (person "Bob" 21) (person "Bob" 20)))
(check-catch 'type-error (person 1 21))
--------------------------------------------------------------------------
Note: let1 is the simplified version of let in the (liii base) library
Sample code 2: Use case class with pattern matching
---------------------------------------------------------------------------------
(let ((bob (person "Bob" 21))
 (get-name (lambda (x)
 (case* x
 ((#<person?>) (x 'name))
 (else (???))))))
 (check (get-name bob) => "Bob")
 (check-catch 'not-implemented-error (get-name 1)))
------------------------------------------------------------------------------------
Note: (???) means (error 'not-implemented-error), it comes for Scala
Sample code 3: Use case class with companion functions
------------------------------------------------------------------------------------
(define-case-class jerson
 ((name string?)
 (age integer?))
 (define (to-string)
 (string-append "I am " name " " (number->string age) " years old!"))
 (define (greet x)
 (string-append "Hi " x ", " (to-string)))
)
-----------------------------------------------------------------------------------
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://cm-mail.stanford.edu/pipermail/cmdist/attachments/20250107/4a16dd98/attachment.html>