Actully racket pattern matching syntax has already supported recursion
scheme(catamorphism):
(define (eval-expr e)
(match e
[`(+ ,(app eval-expr e0) ,(app eval-expr e1))
(+ e0 e1)]
[`(- ,(app eval-expr e0) ,(app eval-expr e1))
(- e0 e1)]
[(? number?) e]
))
在 2019年7月15日星期一 UTC+8上午11:21:14，Raoul Schorer写道：
>
> Hi,
>
> I recently became interested in recursion schemes, and I noticed that
> almost all implementations are in typed languages. I understand the
> advantage of having an implementation using recursion at the type level,
> but why is it that there are so few material in untyped languages?
>
> For instance, would a recursion schemes racket lib be useful or is there
> something I am missing? I noticed that there is no such lib, currently.
>
> Thanks,
> Raoul
>
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