Data Structures

Currency

Currency is a record describing currency and having the following fields:

• id – a keyword identifying a currency unit (e.g. :EUR or :crypto/ETH);
• numeric – a long value being a numeric identifier of ISO-standardized currencies (e.g. 978 or -1 for none);
• scale – an integer of supported scale (decimal places, e.g. 2 or -1 for auto);
• kind – a case-sensitive keyword with currency kind (may be namespaced, e.g. :iso/fiat or :virtual/native);
• domain – a keyword with currency domain (e.g. :ISO-4217, :ISO-4217-LEGACY or :CRYPTO).

Additionally, currency may carry a non-inherent attribute weight (an integer value used when there are conflicting currency codes or numeric IDs during lookup; defaults to 0).

The source of truth for weights is the registry base map cur-id->weight (and the top-level :weights branch in EDN configs/exports). Currency instances stored in registries also carry the weight in metadata as an optimization (hot-path: weighted buckets), but weight does not participate in = / hash semantics. Use currency/weight to read it.

Internally numeric can be -1, meaning there is no numeric ID and scale can be -1 too, meaning the amount of currency can have any number of decimal places.

The currency domain is derived from an identifier if the identifier is namespaced (namespace is upper-cased). The derived code (name part) is upper-cased. Namespace ISO-4217 is treated specially: it is stripped (case-insensitive) and implies :domain :ISO-4217. If there is no namespace the domain can be set to any keyword, with :ISO-4217 having special meaning in some operations as it marks official currencies.

See also doc/30_currency-kinds.md (kind hierarchy) and doc/32_currency_traits.md (traits hierarchy).

Registry

Registry is a record describing a database of currencies with associated metadata and having the following fields:

• cur-id->cur – a map of currency ID to currency record;
• cur-nr->cur – a map of currency numeric ID to currency record;
• ctr-id->cur – a map of country ID to currency record;
• cur-id->ctr-ids – a map of currency ID to set of country IDs;
• cur-id->localized – a map of currency ID to localized properties map;
• cur-id->traits – a map of currency ID to traits (advisory tags);
• cur-id->weight – a map of currency ID to weight (integer; conflict resolution);
• cur-code->curs – a map of currency code keywords to weighted buckets (sorted sets) of currencies;
• cur-nr->curs – a map of currency numeric IDs to weighted buckets (sorted sets) of currencies;
• hierarchies – a record holding hierarchies for currency classification axes (e.g. :domain, :kind, :traits);
• version – a string with registry version;
• ext – a map with extra registry data.

Money

Money is a record describing a monetary value and having the following fields:

• currency – a Currency object;
• amount – an amount of currency stored as a BigDecimal number.