set-car!, set-cdr!无拘无束的球拍? [英] set-car!, set-cdr! unbound in racket?

问题描述

我只是想用 racket 中的 set-car! 和 set-cdr! 做非常简单的代码，但我得到了错误:expand: unbound identifier in module in: set-car! 和 expand: unbound identifier in module in: set-cdr!

I am just trying to do very simple code with set-car! and set-cdr! in racket, but I got the error: expand: unbound identifier in module in: set-car! and expand: unbound identifier in module in: set-cdr!

它们不是在球拍中定义的吗?有人可以帮忙吗?

Aren't they defined in racket? Could anyone help?

推荐答案

需要导入mutable-pairs-6，像这样:

(require rnrs/mutable-pairs-6)

那些程序被移到不同的模块并重命名为mcons、mcar、mcdr、set-mcar！、set-mcdr!、mlist 强调它们对可变数据进行操作，而不像它们的不可变对应物.

Those procedures were moved to a different module and renamed to mcons, mcar, mcdr, set-mcar!, set-mcdr!, mlist to emphasize that they operate on mutable data, unlike their immutable counterparts.

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