A Clojure record is an immutable, map-like value with named fields. Use one when several values share a small, meaningful shape and need a generated type, rather than just a collection of keys. `defrecord` creates the type; its instances support keyword lookup and map operations such as `assoc` and `dissoc`. section 15.7 section 11.0
Create and read a record
(defrecord Point [x y]) (def p (map->Point {:x 1 :y 2})) (:x p) ;; 1 (.x p) ;; 1 `map->Point` accepts a map; keyword lookup and field access both read the declared value. section 15.7
A record behaves like a map, but its type matters:
- Records support `=`, can serve as hash-map keys, and can carry metadata. Equality is based on attributes. section 15.7 section 6.0
- A record can implement interfaces and work with protocols, making it useful when data also needs behavior. section 15.7 section 15.0
- `coll?` returns true for a record, but `(empty record)` throws `UnsupportedOperationException`: removing its integral fields would not produce an empty instance of the same type. section 8.1.4
Prefer `defrecord` to the older `defstruct` for a custom map-like type. A struct guarantees a defined minimum set of keys, but records also provide the generated type used with interfaces and protocols. Neither is a reason to replace every ordinary map: records are intended for a modest number of named fields. section 11.1.4 section 11.0
