Polymorphic variants of Janet’s builtin get, put, each, and related utilities.
They work as expected for builtin data types, but may be customized by defining :jvs/* methods on a table’s prototype.
At minimum a custom data type should implement the :jvs/get, :jvs/put, and :jvs/next, and :jvs/length methods.
If one wishes for put-in to behave differently, it would be wise to implement the :jvs/init method as well.
For more reliable cloning, data types should implement :jvs/clone in a manner appropriate for the data type.
To allow reversing the entries in an ordered data structure, the structure should implement :jvs/reverse and :jvs/reverse!.
The jvs interface may be implemented without depending on jvs itself, in case one wishes to be compatible with jvs without forcing the dependency on everyone.
(import jvs)
# This is a simple prototype that implements the jvs interface by storing values
# in the :data field instead of within the primary table itself.
(def MyType
@{:jvs/get
(fn [self k &opt v]
(get-in self [:data k] v))
:jvs/put
(fn [self k v]
(put-in self [:data k] v))
:jvs/next
(fn [self &opt k]
(next (in self :data) k))
:jvs/length
(fn [self] (-> (in self :data []) length))
:jvs/clone
(fn [self]
(def clone (table/clone self))
(update clone :data |(-?> $ table/clone)))})
# Create an instance of a table with the above prototype.
(def custom (table/setproto @{} MyType))
# The custom tables store values within the :data field.
(jvs/put custom :foo "bar")
(jvs/put custom :bar "baz")
# Create a normal table with no special properties.
(def tbl @{})
# When presented with a normal table, jvs/put falls back to the builtin put
# function instead of using a custom implementation.
(jvs/put tbl :foo "bar")
# The iteration works as expected, using :jvs/next and :jvs/get for custom data
# types, and the builtin next and get functions for builtin data types.
(jvs/eachp kv tbl (pp kv))
(jvs/eachp kv custom (pp kv))
# Cloning the table works as expected: the data field is itself cloned when it
# would otherwise be assigned to to the new table by reference.
(assert (not= (in custom :data)
(in (jvs/clone custom) :data)))jvs is made freely available under the terms of the BSD 0-Clause License.
Third-party contributions shall be licensed under the same terms unless explicitly stated otherwise.