[docs] Add "currency type" to the lexicon

[philipturner]

I don't understand why it says "currency", which means money. There might be some Swift data type for money, but I haven't heard of it yet. Also, the explanation misses that the entire document just covers built-in Swift types. Did you mean "concurrency"?

[CodaFi]

There is a difference here!

The compiler understands Builtin types like Builtin.NativeObject, and it understands much higher-level common user types like String. The types in the standard library are not considered builtins - they're built atop builtins more often than not. The document linked here describes optimization opportunities exposed by annotations and structures attached these higher-level types and associated operations.

"Currency" (often also "vocabulary") types are types that one reaches for in most common usages of the language. Do you want to manipulate a string - pick String, not UnsafeMutableBufferPointer<CChar>. Do you want a pack of unique elements - pick Set<T>!

[philipturner]

Then could the documentation clarify what "currency" means or provide a hyperlink? I didn't see it in Lexicon.md, and from the point of view of someone who doesn't know what it means, it looks like a misspelling of "Concurrency".

[WowbaggersLiquidLunch]

also relevant answer on the forums: https://forums.swift.org/t/what-does-currency-type-mean/41065/2

[philipturner]

Then let’s add it to the lexicon and link it!

…

Sent from my iPhone

On Jan 17, 2022, at 3:35 AM, 冀卓疌 ***@***.***> wrote:  also relevant answer on the forums: https://forums.swift.org/t/what-does-currency-type-mean/41065/2 — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.

[philipturner]

The definition for currency still needs to be refined, could anyone help me here?

[CodaFi]

Thanks

⛵

[CodaFi]

Note to self: manually squash this

@swift-ci smoke test

[philipturner]

@CodaFi you may need to retest this because of a one-character change.

[xwu]

@swift-ci smoke test