The Sidef Programming Language

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🌟 Why Sidef?

Sidef is a modern, expressive programming language that combines the elegance of Ruby, the versatility of Raku, and the mathematical power of a built-in computer algebra system. It features exact rational arithmetic by default, an extensive number theory library (1,000+ functions), and seamless Perl module integration — making it equally at home for scripting, mathematical research, and general-purpose programming.

# Exact rational arithmetic — no floating-point surprises
say (1/3 + 1/6) #=> 1/2
# Built-in number theory
say (2**127 - 1) #=> 170141183460469231731687303715884105727 (Mersenne prime)
say factor(2**64 - 1) #=> [3, 5, 17, 257, 641, 65537, 6700417]
# Expressive, concise syntax
say 29.primes #=> [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]

✨ Key Features

Programming Paradigms

• Object-oriented programming with multiple dispatch
• Functional programming and pattern matching
• Lexical scoping and closures
• Keyword arguments and optional lazy evaluation

Numeric Computing

• Exact rational numbers by default
• Arbitrary-precision integers, floats, and complex numbers
• 1,000+ built-in number theory functions (backed by GMP, MPFR, MPC)
• Gaussian integers, quaternions, matrices, polynomials

Language & Integration

• Regular expressions and string interpolation
• Optional dynamic type checking
• Seamless Perl module integration
• REPL with interactive help (-H flag)

🚀 Quick Start

Prerequisites

Sidef requires Perl 5.18+ and the following C libraries:

Debian/Ubuntu:

sudo apt-get install libgmp-dev libmpfr-dev libmpc-dev

Arch Linux:

sudo pacman -S gmp mpfr libmpc

Termux:

pkg install perl make clang libgmp libmpfr libmpc

Installation

Via CPAN:

cpan Sidef
# or (skip tests for faster install):
cpan -T Sidef
# or with cpanminus:
cpanm Sidef

Build from source:

git clone https://github.com/trizen/sidef.git
cd sidef
perl Makefile.PL
make
make test
make install

Via AUR:

trizen -S sidef

Platform packages:

• Arch Linux: AUR package
• Slackware: SlackBuilds
• Other systems: See pkgs.org

Hello World

say "Hello, World!"

sidef hello.sf
sidef -E 'say "Hello, World!"'
sidef -i # start the REPL

Try It Online

Experiment with Sidef instantly at Try It Online without any installation.

🔤 Language at a Glance

Variables and Types

var name = "Sidef" # String
var num = 42 # Number (exact integer)
var ratio = 3/7 # Number (exact rational)
var arr = [1, 2, 3] # Array
var hash = Hash(a => 1, b => 2) # Hash
var block = {|n| n.is_prime } # Block

Functions and Pattern Matching

func greet(name) { "Hello, #{name}!" }
say greet("world") #=> Hello, world!
# Multi-dispatch / pattern matching
func fib({|n| n == 0 }) { 0 }
func fib({|n| n == 1 }) { 1 }
func fib(n) { fib(n-1) + fib(n-2) }
say fib(10) #=> 55

Object-Oriented Programming

class Animal(name, sound) {
 method speak { say "#{name} says #{sound}!" }
}
class Dog(name, sound="woof") < Animal {
 method fetch { say "#{name} fetches the ball!" }
}
var d = Dog("Rex")
d.speak #=> Rex says woof!
d.fetch #=> Rex fetches the ball!

Functional Programming

var nums = 1..10 # RangeNumber object
# Map, filter, reduce
var evens = nums.grep { .is_even } #=> [2, 4, 6, 8, 10]
var squares = nums.map { |n| n**2 } #=> [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
var total = nums.reduce { |a, b| a + b } #=> 55
say evens
say squares
say total

Number Theory

say primes(50, 100) # array of primes in range [50, 100]
say prime_count(10**9) # number of primes up to 10^9
say prime(100) # 100th prime => 541
say 12.divisors # [1, 2, 3, 4, 6, 12]
say euler_phi(100) # Euler's totient => 40
say gcd(48, 18) # => 6
say is_prime(2**521 - 1) # Mersenne prime check => true

Lazy Evaluation

# Infinite lazy list of primes
var lazy_primes = (2..Inf -> lazy.grep { .is_prime })
say lazy_primes.first(10) #=> [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]

⌨️ Command-Line Reference

sidef [options] [script.sf] [script-arguments]

Examples:

sidef -E 'say 10.of { |i| i**2 }' # one-liner
sidef -i # start REPL
sidef -i script.sf # run script in REPL
sidef -C script.sf # syntax check
sidef -c -o output.pl script.sf # compile to Perl
sidef -P 400 -E 'say sqrt(2)' # 400-bit precision
sidef -O1 script.sf # with optimization
sidef -r script.sf # deparse to Sidef
sidef -t tests/*.sf # run test files

🖥️ Interactive Mode (REPL)

Start the REPL with sidef -i:

$ sidef -i
sidef> say "Hello!"
Hello!
sidef> x = 2**64
18446744073709551616
sidef> x.is_prime
false
sidef> is_prime(2**127 - 1)
true
sidef> 1..10 -> map { .square }.sum
385
sidef> quit

Use -H to open interactive documentation help:

sidef -H

🎯 Code Examples

Classes and Inheritance

class Shape {
 method area { die "Not implemented" }
 method describe { say "I am a #{self.class} with area #{self.area}" }
}
class Circle(r) < Shape {
 method area { Num.pi * r**2 }
}
class Rectangle(w, h) < Shape {
 method area { w * h }
}
Circle(5).describe #=> I am a Circle with area 78.539...
Rectangle(4, 6).describe #=> I am a Rectangle with area 24

Functional Array Processing

# FizzBuzz in one line
say (1..20 -> map { |n|
 n%%15 ? "FizzBuzz" : (n%%3 ? "Fizz" : (n%%5 ? "Buzz" : n))
})
# Pipeline style
(1..50).grep { .is_prime } \
 .map { .square } \
 .first(5) \
 .say #=> [4, 9, 25, 49, 121]

Number Theory One-Liners

say 100.by { .is_prime } # first 100 primes
say sum(1..100) #=> 5050
say prod(1..10) #=> 3628800 (10!)
say { .euler_phi }.map(1..10) #=> [1, 1, 2, 2, 4, 2, 6, 4, 6, 4]

The Y Combinator

Demonstrating functional programming with the Y combinator:

var y = ->(f) {->(g) {g(g)}(->(g) { f(->(*args) {g(g)(args...)})})}
var fac = ->(f) { ->(n) { n < 2 ? 1 : (n * f(n-1)) } }
say 10.of { |i| y(fac)(i) } #=> [1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880]
var fib = ->(f) { ->(n) { n < 2 ? n : (f(n-2) + f(n-1)) } }
say 10.of { |i| y(fib)(i) } #=> [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

Sierpinski Triangle

ASCII generation of the Sierpinski triangle:

func sierpinski_triangle(n) {
 var triangle = ['*']
 { |i|
 var sp = (' ' * 2**i)
 triangle = (triangle.map {|x| sp + x + sp} +
 triangle.map {|x| x + ' ' + x})
 } * n
 triangle.join("\n")
}
say sierpinski_triangle(4)

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Mandelbrot Set

ASCII visualization of the Mandelbrot set:

func mandelbrot(z, r=20) {
 var c = z
 r.times {
 z = (z*z + c)
 return true if (z.abs > 2)
 }
 return false
}
for y in (1 `downto` -1 `by` 0.05) {
 for x in (-2 `upto` 0.5 `by` 0.0315) {
 print(mandelbrot(Complex(x, y)) ? ' ' : '#')
 }
 print "\n"
}

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📚 Documentation & Learning Resources

Example Code

💬 Community & Support

Have questions or need help? Join the conversation:

• Discussion Forum - Q&A and community discussions
• GitHub Issues - Bug reports and feature requests

📦 Distribution Availability

🤝 Contributing

Contributions of all kinds are welcome — bug reports, feature suggestions, documentation improvements, and pull requests. Please read CONTRIBUTING.md for guidelines on:

• Reporting bugs and suggesting features
• Setting up a development environment
• Code style and commit message conventions
• The pull request review process

📄 License and Copyright

Copyright © 2013-2026 Daniel Șuteu, Ioana Fălcușan

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License (2.0).

Full license: perlfoundation.org/artistic-license-20.html