# \#unique **URL:** https://racket.discourse.group/tag/unique/121.md [Latest](https://racket.discourse.group/latest.md) · [Categories](https://racket.discourse.group/categories.md) · [Tags](https://racket.discourse.group/tags.md) --- ## [Function and macro to define unique values](https://racket.discourse.group/t/function-and-macro-to-define-unique-values/1097)
**Author:** [@sschwarzer](https://racket.discourse.group/u/sschwarzer)\ **Replies:** 9\ **Last updated:** [June 27, 2022, 5:29am UTC](https://racket.discourse.group/t/function-and-macro-to-define-unique-values/1097 "2022-06-27T05:29:33Z")
I've seen the idiom (struct unique-value ()) to create unique values, for example as default arguments in a function to check with (eq? argument unique-value) if anything was passed for the argument. Since I have only…