Enhances data manipulation by offering core data structures like lists, vectors, maps, and sequences. Supports persistent collections for efficient updates and keyword identifiers for fast equality tests.
y is a Kotlin multiplatform library that aims to port and provide effective
concepts inspired by other languages or libraries.
This module provides core data structures and utility functions.
List:
val list1 = l<Int>(1,2,3) // (1 2 3)
val empty = l<Int>() // ()
// From Kotlin's List<E> to PersistentList<E>
val list2 = listOf<Int>(1, 2, 3).toPlist() // (1 2 3)
To add an item to a list, use conj(e), it puts the item at the front
of the list and returns a new list.
l<Int>(1,2,3).conj(4) // (4 1 2 3)
To get the size of a list:
l<Int>(1,2,3).count // 3
Vector:
val vec1 = v<Int>(1, 2, 3) // [1 2 3]
val empty = v<Int>() // []
// From Kotlin's List<E> to PersistentVector<E>
val vec2 = listOf<Int>(1, 2, 3).toPvector() // [1 2 3]
To add an item to a vector, use conj(e), it puts the item at the end
of the vector and returns a new vector.
v<Int>(1, 2, 3).conj(4) // [1 2 3 4]
To get the size of a vector:
v<Int>(1, 2, 3).count // 3
To get an item by index, you can use get(index) operator
or nth(index)/nth(index, def)
v<Int>(1, 2, 3)[1] // 2
v<Int>(1, 2, 3).nth(2) // 3
v<Int>(1, 2, 3).nth(5, -1) // -1
To get the items in reverse order as a sequence, use reverse()
v<Int>(1, 2, 3).reverse() // (3 2 1)
PersistentArrayMap:
This map should be only used when you have very small maps and want to
maintain key order, since it is just an array of [key,val..key,val].
Subsequent assoc-ing will eventually return a PersistentHashMap.
val map1 = m<String, Int>("1" to 1, "2" to 2) // {"1" 1, "2" 2}
//From Kotlin's Map<K,V> to PersistentArrayMap<K,V>
val map2 = mapOf<String, Int>("1" to 1, "2" to 2).toPArrayMap() // {"1" 1, "2" 2}
PersistentHashMap:
This map requires keys that correctly support hashCode and equals.
val map1 = hashMap<String, Int>("1" to 1, "2" to 2) // {"1" 1, "2" 2}
//From Kotlin's Map<K,V> to PersistentHashMap<K,V>
val map2 = mapOf<String, Int>("1" to 1, "2" to 2).toPhashMap() // {"1" 1, "2" 2}
PersistentHashSet:
val set1 = hs<Int>(1, 2, 2, 3, 3) // #{1 2 3}
//From Kotlin's Set<E> to PersistentHashSet<E>
val set2 = setOf<Int>(1, 2, 2, 3 ,3).toPhashSet() // #{1 2 3}
Sequence:
All collections support a member function seq() that return a
sequence of type ISeq<E> that can walk the entire collection. A
sequance provides three key member functions:
first() : return the first element in the sequence.rest() : returns all of the rest elements of the sequence that
came after first element, as a sequence.cons(element) : always adds to the front of the sequence and
returns a sequence.Keywords are identifiers that provide very fast equality tests, and they have a string name. If you call toString() on a keyword it returns the name prefixed by a ':' which is not part of the name.
// To create a Keyword, use the utility function `k(name)`:
val keyword = k("a") // :a
// invoke(map, default = null) operator
val map = hashMap("a" to 1)
val key = k("a")
val default = k("none")
key(map, default) // :none
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