This small clojure library allows you to define Mutables, a kind of deftype
with all of its fields marked as :unsynchronized-mutable which allows setting
values from outside and works like a regular map (i.e. Implements ILookup like
defrecord).
As with regular deftype, type hints work, and primitive type hints internally
create a Java class with primitive types. Similarly, other kinds of type hints
are used by the compiler but will not be enforced at runtime (i.e. you can set a
field hinted as ^Integer to the value "Hello", but not if it's an ^int).
The defmutable in this repo is inspired by the great
https://github.com/arcadia-unity/Arcadia library.
Mutables follow the same structure as a deftype. Here's an example:
(require '[mutant.core :as mut])
(mut/defmutable MyType [^int a, ^String b])
(let [m (->MyType 1 "2")]
(mut/mut! m :a 25)
(mut/mut! m :b "Hello")
(println (:a m)) ; => 25
(println (:b m)) ; => "Hello"
(mut/mut! m :a "Hello") ; => ClassCastException
(mut/mut! m :b 3)); => This worksClojure doesn't have a macro like this for a good reason. Most of the time there
is no need for the kind of Mutables introduced by this project. This should
only be used in very tight loops of the codebase, and always as an
implementation detail, never as part of an API.
Please use with caution and only when really necessary. Also remember to always measure first before optimizing!