# Hash-table name?

**URL:** <https://racket.discourse.group/t/hash-table-name/1699>\
**Category:** General\
**Created:** [February 11, 2023, 10:30am UTC](https://racket.discourse.group/t/hash-table-name/1699 "2023-02-11T10:30:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![spdegabrielle](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/spdegabrielle/32/95_2.png) [@spdegabrielle](https://racket.discourse.group/u/spdegabrielle)\
**Post date:** [February 11, 2023, 10:30am UTC](https://racket.discourse.group/t/hash-table-name/1699/1 "2023-02-11T10:30:42Z")

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I’ve been following the topic [RFC: hash table pattern matching](https://racket.discourse.group/t/rfc-hash-table-pattern-matching/1686).

The Racket Reference ([4.15&nbsp;Hash Tables](https://docs.racket-lang.org/reference/hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash%29%29)) mentions performance differences between mutable and immutable versions.

In other languages Hash tables go by other names in other names; _dictionary_ (Python?), _associative array_(Awk?) , _map_ (Haskell?), and I’m sure others.

Why not name them for the algorithm or performance characteristics?

I’m sure this is a gap in my CS education, so please forgive my ignorance.

Best regards  
Stephen  
:beetle:

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**Author:** ![gus-massa](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/gus-massa/32/507_2.png) [@gus-massa](https://racket.discourse.group/u/gus-massa)\
**Post date:** [February 11, 2023, 5:15pm UTC](https://racket.discourse.group/t/hash-table-name/1699/2 "2023-02-11T17:15:23Z")

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IIRC, in Racket BC `mutable hash` are actually hash tables, but `immutable hash` use a different algorithm under the hood but have the same user interface.

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**Author:** ![samth](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/samth/32/3_2.png) [@samth](https://racket.discourse.group/u/samth)\
**Post date:** [February 13, 2023, 9:20pm UTC](https://racket.discourse.group/t/hash-table-name/1699/3 "2023-02-13T21:20:56Z")

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Also, in all cases Racket hash tables are implemented based on a hash of the key.