Jay has a really nice `sstruct' macro that may do what you want.
https://github.com/jeapostrophe/exp/blob/master/sstruct.rkt
Examples in
https://github.com/jeapostrophe/exp/blob/master/sstruct-tests.rkt
IMO, there are a lot of good ideas in there that would be nice to have
for Racket's `struct', or at least installable as a package.
Vincent
At Sat, 22 Jun 2013 10:23:51 +0200,
Patrick Useldinger wrote:
>
> Hi
>
> I can't find a way to have a per-field default value in a struct, such
> as in Common Lisp:
>
> ? (defstruct person (name "James" :type string) (age 1 :type number))
> PERSON
> ? (defparameter p (make-person))
> P
> ? p
> #S(PERSON :NAME "James" :AGE 1)
> ? (defparameter p (make-person :name "Paul"))
> P
> ? p
> #S(PERSON :NAME "Paul" :AGE 1)
> ? (defparameter p (make-person :name "Paul" :age 10))
> P
> ? p
> #S(PERSON :NAME "Paul" :AGE 10)
>
>
> The only thing I find is #:auto-value, which applies to all fields.
>
> Is there a way to do the same in Racket? If not, is there a specific
> reason for this choice?
>
> -pu
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