Design Decisions

This gem is opinionated. Those opinions are part of its value.

Atomic integers, not decimal storage

The atomic value is always an integer count of the smallest unit. That keeps equality, hashing, and persistence crisp.

One class, registry-driven types

Type identity lives in the registry because adding a new symbol should be a configuration action, not a subclass ceremony.

Directional rates only

Rates are directional because real conversion systems are directional.

Display units are not conversions

Showing gold in grams is still showing gold. The type has not changed.

Explicit remainder

split and allocate return remainder explicitly because silent distribution bakes in a business preference.

Lockable global registry

The global registry is a practical boot-time configuration surface. lock! exists so the convenience of a shared registry does not imply ongoing runtime mutability.