Persistent data structures for Go

Check out https://godoc.org/github.com/mndrix/ps

From it's documentation:

Fully persistent data structures. A persistent data structure is a data structure that always preserves the previous version of itself when it is modified. Such data structures are effectively immutable, as their operations do not update the structure in-place, but instead always yield a new structure.

Persistent data structures typically share structure among themselves. This allows operations to avoid copying the entire data structure.

ps has small but effective API for manipulating lists and maps of data:

type List interface {
   Cons(val interface{}) List
   ForEach(f func(interface{}))
   Head() interface{}
   IsNil() bool
   Reverse() List
   Size() int
   Tail() List
}
func NewList() List
type Map interface {
   Delete(key string) Map
   ForEach(f func(key string, val interface{}))
   IsNil() bool
   Keys() []string
   Lookup(key string) (interface{}, bool)
   Set(key string, value interface{}) Map
   Size() int
   String() string
   UnsafeMutableSet(key string, value interface{}) Map
}
func NewMap() Map

For more details see https://godoc.org/github.com/mndrix/ps