
- LISP Tutorial
- LISP - Home
- LISP - Overview
- LISP - Environment
- LISP - REPL
- LISP - Program Structure
- LISP - Basic Syntax
- LISP - Data Types
- Lisp Macros
- LISP - Macros
- LISP - Backquote and Comma
- LISP - Code Generation Using Macro
- LISP - Variable Capture and Hygienic macro
- LISP - Scope and Binding
- LISP - Macro Writing Style
- LISP - Macro Characters
- LISP - Read-Time Macros
- LISP - Compiler Macros
- LISP - Uses of Macros
- Lisp Functions
- LISP - Functions
- LISP - Functions vs Macros
- LISP - Calling Function using funcall
- LISP - Calling Function using apply
- LISP - Closures
- LISP - Functions as Arguments
- LISP - Functions as Return Values
- LISP - Recursion
- LISP - Built-in Functions
- Lisp Predicates
- LISP - Predicates
- LISP - Generic Data Type Predicates
- LISP - Specific Data Type Predicates
- LISP - Equality Predicates
- LISP - Numeric Predicates
- LISP - Comparison Predicates
- LISP - Logical Predicates
- LISP - List Predicates
- LISP - Custom Predicates
- LISP - Chaining Predicates
- Lisp Arrays
- LISP - Arrays
- LISP - Adjustable Arrays
- LISP - Fill Pointers in Arrays
- LISP - Specialized Arrays
- LISP - Arrays Properties
- LISP - Iterating over Arrays
- LISP - Multidimensional Arrays
- LISP - Row-Major Order
- Lisp Strings
- LISP - Strings
- LISP - String Concatenation
- LISP - String Comparison
- LISP - String Case Conversion
- LISP - String Trimmimg
- LISP - String Searching
- LISP - Getting Substring
- LISP - String Replacement
- LISP - Sorting Strings
- LISP - Merging Strings
- LISP - Accessing Characters of String
- LISP - String length
- LISP - Escape Sequences
- Lisp Sequences
- LISP - Sequences
- LISP - Accessing Element of Sequence
- LISP - Sequence length
- LISP - Getting Subsequence
- LISP - Search Element in Sequence
- LISP - Sequence Concatenation
- LISP - Reversing a Sequence
- LISP - Mapping Sequence Element
- LISP - position of Element
- LISP - Remove an Element
- LISP - Sort Sequence
- LISP - Merge Sequences
- LISP - every function
- LISP - some function
- LISP - notany function
- LISP - notevery function
- Lisp Lists
- LISP - Lists
- LISP - Accessing Elements of Lists
- LISP - Modifications to Lists
- LISP - Using mapcar on List
- LISP - Using mapc on List
- LISP - Using reduce on List
- LISP - Removing elements from List
- LISP - Reversing a List
- LISP - Sorting a List
- LISP - Searching a List
- LISP - List vs Vectors
- LISP - Matrix Multiplication
- Lisp Vectors
- LISP - Vectors
- LISP - Creating Vectors
- LISP - Accessing Elements of Vectors
- LISP - Modifications to Vectors
- LISP - Adjustable Vectors
- LISP - Specialized Vectors
- LISP - Vector Functions
- Lisp Set
- LISP - Set
- LISP - Adding elements to the Set
- LISP - Getting SubSet from a Set
- LISP - Set Difference
- LISP - Set Exclusive OR
- LISP - Set Intersection
- LISP - Set Union
- LISP - Representing Set with HashTable
- LISP - List as Set vs HashTable as Set
- Lisp Tree
- LISP - Tree
- LISP - Recursive Traversal
- LISP - Inorder Traversal
- LISP - Preorder Traversal
- LISP - Postorder Traversal
- LISP - Depth First Traversal
- LISP - Modifying Tree
- LISP - Search Tree
- LISP - Binary Tree
- Lisp Hash Table
- LISP - Hash Table
- Adding Values to Hash Table
- Removing Values from Hash Table
- Updating Values of Hash Table
- Iterating Hash Table Entries
- Searching key in HashTable
- Checking Size of HashTable
- Using Custom Equality Check
- Lisp - Input − Output
- LISP - Input − Output
- LISP - Streams
- LISP - Reading Data from Streams
- LISP - Writing Data to Streams
- LISP - File I/O
- LISP - String I/O
- LISP - Formatting with Format
- LISP - Interactive I/O
- LISP - Error Handling
- LISP - Binary I/O
- Lisp - Structures
- LISP - Structures
- LISP - Accessors and Mutators
- LISP - Structure Options
- LISP - Structure Types
- LISP - Applications and Best Practices
- Lisp - CLOS
- LISP - CLOS
- Lisp - Objects
- LISP - Class
- LISP - Slots and Accessors
- LISP - Generic Functions
- LISP - Class Precedence
- LISP - Metaobject Protocol
- LISP - Multimethods
- LISP - Multiple Inheritance
- LISP - Method Combinations
- LISP - Method Combinations
- LISP - :before Method Combination
- LISP - :primary Method Combination
- LISP - :after Method Combination
- LISP - :around Method Combination
- LISP - + Method Combination
- LISP - and Method Combination
- LISP - append Method Combination
- LISP Useful Resources
- Lisp - Quick Guide
- Lisp - Useful Resources
- Lisp - Discussion
Lisp - Operators
An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations. LISP allows numerous operations on data, supported by various functions, macros and other constructs.
The operations allowed on data could be categorized as −
- Arithmetic Operations
- Comparison Operations
- Logical Operations
- Bitwise Operations
Arithmetic Operations
The following table shows all the arithmetic operators supported by LISP. Assume variable A holds 10 and variable B holds 20 then −
Operator | Description | Example |
---|---|---|
+ | Adds two operands | (+A B) will give 30 |
- | Subtracts second operand from the first | (- A B) will give -10 |
* | Multiplies both operands | (* A B) will give 200 |
/ | Divides numerator by de-numerator | (/ B A) will give 2 |
mod,rem | Modulus Operator and remainder of after an integer division | (mod B A )will give 0 |
incf | Increments operator increases integer value by the second argument specified | (incf A 3) will give 13 |
decf | Decrements operator decreases integer value by the second argument specified | (decf A 4) will give 9 |
Comparison Operations
Following table shows all the relational operators supported by LISP that compares between numbers. However unlike relational operators in other languages, LISP comparison operators may take more than two operands and they work on numbers only.
Assume variable A holds 10 and variable B holds 20, then −
Operator | Description | Example |
---|---|---|
= | Checks if the values of the operands are all equal or not, if yes then condition becomes true. | (= A B) is not true. |
/= | Checks if the values of the operands are all different or not, if values are not equal then condition becomes true. | (/= A B) is true. |
> | Checks if the values of the operands are monotonically decreasing. | (> A B) is not true. |
< | Checks if the values of the operands are monotonically increasing. | (< A B) is true. |
>= | Checks if the value of any left operand is greater than or equal to the value of next right operand, if yes then condition becomes true. | (>= A B) is not true. |
<= | Checks if the value of any left operand is less than or equal to the value of its right operand, if yes then condition becomes true. | (<= A B) is true. |
max | It compares two or more arguments and returns the maximum value. | (max A B) returns 20 |
min | It compares two or more arguments and returns the minimum value. | (min A B) returns 10 |
Logical Operations on Boolean Values
Common LISP provides three logical operators: and, or, and not that operates on Boolean values. Assume A has value nil and B has value 5, then −
Operator | Description | Example |
---|---|---|
and | It takes any number of arguments. The arguments are evaluated left to right. If all arguments evaluate to non-nil, then the value of the last argument is returned. Otherwise nil is returned. | (and A B) will return NIL. |
or | It takes any number of arguments. The arguments are evaluated left to right until one evaluates to non-nil, in such case the argument value is returned, otherwise it returns nil. | (or A B) will return 5. |
not | It takes one argument and returns t if the argument evaluates to nil. | (not A) will return T. |
Bitwise Operations on Numbers
Bitwise operators work on bits and perform bit-by-bit operation. The truth tables for bitwise and, or, and xor operations are as follows −
p | q | p and q | p or q | p xor q |
---|---|---|---|---|
0 | 0 | 0 | 0 | 0 |
0 | 1 | 0 | 1 | 1 |
1 | 1 | 1 | 1 | 0 |
1 | 0 | 0 | 1 | 1 |
Assume if A = 60; and B = 13; now in binary format they will be as follows: A = 0011 1100 B = 0000 1101 ----------------- A and B = 0000 1100 A or B = 0011 1101 A xor B = 0011 0001 not A = 1100 0011
The Bitwise operators supported by LISP are listed in the following table. Assume variable A holds 60 and variable B holds 13, then −
Operator | Description | Example |
---|---|---|
logand | This returns the bit-wise logical AND of its arguments. If no argument is given, then the result is -1, which is an identity for this operation. | (logand a b)) will give 12 |
logior | This returns the bit-wise logical INCLUSIVE OR of its arguments. If no argument is given, then the result is zero, which is an identity for this operation. | (logior a b) will give 61 |
logxor | This returns the bit-wise logical EXCLUSIVE OR of its arguments. If no argument is given, then the result is zero, which is an identity for this operation. | (logxor a b) will give 49 |
lognor | This returns the bit-wise NOT of its arguments. If no argument is given, then the result is -1, which is an identity for this operation. | (lognor a b) will give -62, |
logeqv | This returns the bit-wise logical EQUIVALENCE (also known as exclusive nor) of its arguments. If no argument is given, then the result is -1, which is an identity for this operation. | (logeqv a b) will give -50 |