# Mutable hash sets in typed Racket

**URL:** <https://racket.discourse.group/t/mutable-hash-sets-in-typed-racket/1452>\
**Category:** Questions & Answers\
**Tags:** typed-racket\
**Created:** [November 11, 2022, 3:22pm UTC](https://racket.discourse.group/t/mutable-hash-sets-in-typed-racket/1452 "2022-11-11T15:22:55Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![hendrikboom3](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/hendrikboom3/32/2748_2.png) [@hendrikboom3](https://racket.discourse.group/u/hendrikboom3)\
**Post date:** [November 11, 2022, 3:22pm UTC](https://racket.discourse.group/t/mutable-hash-sets-in-typed-racket/1452/1 "2022-11-11T15:22:55Z")

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Mutable sets seem to be in Racket.  
However, in typed Racket, the Setof type constructor's description explicitly rejects mutable sets.  
And the regular Racket operation mutable-seteq seems to be unavailable.  
Is this truly the case? Is there some compelling reason to ban mutablility? Or is it just an oversight?  
How should I work around it?  
-- hendrik