[boronine]

I think most of this is covered by a good Decimal API, currency stuff probably shouldn't be embedded into a language because it changes: currencies come and go, get redenominated etc. Although one simple thing that would be useful is keeping track of abstract units, e.g. throwing an error when attempting to do 10 USD + 10 EUR.

[oblio]

Don't we embed timezones, though?

[explorigin]

Timezone conversions don't change by the minute. Currency conversions do.

[oblio]

Do most applications use the minute-to-minute conversions or some daily rate?

I'm fairly sure that for example for RON, the Romanian Central Bank only publishes daily rates, for example.