Lisp Programming Language Cheatsheet

Basic cheatsheet for the Lisp programming language, covering some fundamental topics:

1. Variables and Data Types

;; Variables
(setq my-variable 10)

;; Data Types
(setq integer-var 42)
(setq float-var 3.14)
(setq string-var "Hello, Lisp!")
(setq list-var '(1 2 3))
(setq symbol-var 'symbol)

2. Basic Operations

;; Arithmetic Operations
(setq sum (+ 2 3))
(setq difference (- 5 2))
(setq product (* 4 6))
(setq quotient (/ 8 2))

;; Comparison
(setq is-equal (= 10 10))
(setq not-equal (/= 5 10))

3. Conditional Statements

;; If Statement
(if (< x 0)
    (setq result "Negative")
    (setq result "Non-negative"))

;; Cond Statement
(cond
  ((= x 0) (setq result "Zero"))
  ((< x 0) (setq result "Negative"))
  ((> x 0) (setq result "Positive"))
  (t (setq result "Unknown")))

4. Loops

;; While Loop
(setq counter 0)
(while (< counter 5)
  (print counter)
  (setq counter (+ counter 1)))

;; For Loop
(dotimes (i 5)
  (print i))

5. Functions

;; Define a Function
(defun greet (name)
  (format t "Hello, ~a!" name))

;; Call a Function
(greet "Lisp")

6. Lists and Sequences

;; Lists
(setq my-list '(1 2 3 4))

;; Accessing Elements
(setq first-element (first my-list))
(setq rest-of-list (rest my-list))

;; Adding Elements
(setq new-list (cons 0 my-list))

;; Mapping a Function to a List
(setq squared-list (mapcar #'(lambda (x) (* x x)) my-list))

7. Symbols

;; Define a Symbol
(setq my-symbol 'example)

;; Check if a Variable is a Symbol
(symbolp my-symbol)

8. Advanced Topics

;; Closures
(defun make-adder (x)
  #'(lambda (y) (+ x y)))

(setq add5 (make-adder 5))
(funcall add5 3) ; Returns 8

;; Recursion
(defun factorial (n)
  (if (= n 0)
      1
      (* n (factorial (- n 1)))))

This cheatsheet covers some basic concepts in Lisp. Remember, Lisp is known for its powerful features, so this is just a starting point!

Official Reference.