Lisp provides a variety of built-in data structures that are commonly used in Lisp programming. These data structures are designed to handle different types of data and support various operations efficiently. Here are some commonly used data structures in Lisp:
1. Lists : * Lists are one of the fundamental data structures in Lisp.
* A list is a sequence of elements enclosed in parentheses.
* Lists can hold elements of any type, including other lists, and they can be nested to create complex data structures.
* Lists are extensively used for representing and manipulating data in Lisp, and they support operations like cons, car, cdr, and recursion.
2. Arrays : * Arrays provide a way to store and access elements using numeric indices.
* Lisp supports both one-dimensional and multi-dimensional arrays.
* Arrays are useful for efficient random access and are commonly used for storing large amounts of data or when element access by index is required.
3. Strings : * Strings are used to represent and manipulate textual data.
* Lisp strings are enclosed in double quotes.
* Strings support operations for string concatenation, substring extraction, searching, and modification.
4. Hash Tables : * Hash tables, also known as associative arrays or dictionaries, provide a mapping between keys and values.
* They are useful for efficient lookup and retrieval of data based on a unique key.
* Hash tables allow constant-time access to values based on the key and are commonly used for implementing symbol tables, caches, and data caches.
5. Sets : * Sets are unordered collections of unique elements.
* Lisp provides a set data structure that allows efficient membership testing, union, intersection, and difference operations.
* Sets are commonly used for handling collections of unique elements and performing set-based operations.
6. Trees : * Trees are hierarchical data structures consisting of nodes connected by edges.
* Lisp supports tree-like structures using lists or arrays, where elements can be nested to represent parent-child relationships.
* Trees are used for representing hierarchical data, such as directories, XML/HTML structures, and abstract syntax trees.
7. Queues and Stacks : * Queues and stacks are abstract data types used for managing collections of elements.
* Queues follow the First-In-First-Out (FIFO) principle, while stacks follow the Last-In-First-Out (LIFO) principle.
* Lisp provides built-in support for implementing queues and stacks using lists or arrays.
These are some of the commonly used data structures in Lisp. Lisp's flexible and extensible nature allows developers to create and work with custom data structures as well, based on the specific requirements of their programs.
