Dylan is a multi-paradigm functional and object-oriented programming language. It is dynamic while providing a programming model designed to support efficient machine code generation, including fine-grained control over dynamic and static behaviors.

define class <vehicle> (<object>)
  slot owner :: <string>,
    init-keyword: owner:,
    init-value: "Northern Motors";
end;

define class <car> (<vehicle>)
end;

define class <truck> (<vehicle>)
  slot capacity,
    required-init-keyword: tons:;
end;

define generic tax
    (v :: <vehicle>) => (tax-in-dollars :: <float>);

define method tax
    (v :: <vehicle>) => (tax-in-dollars :: <float>)
  100.00
end;

define method tax
    (c :: <car>) => (tax-in-dollars :: <float>)
  50.0
end;

define method tax
    (t :: <truck>) => (tax-in-dollars :: <float>)
  // standard vehicle tax plus $10/ton
  next-method() + t.capacity * 10.0
end;

define function make-fibonacci()
  let n = 0;
  let m = 1;
  method ()
    let result = n + m;
    n := m;
    m := result  // return value
  end
end;

define constant fib = make-fibonacci();

for (i from 1 to 15)
  format-out("%d ", fib())
end;

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New release: 2019.1 - 2019-03-31

Open Dylan 2019.1 released.

New release: 2014.1 - 2015-01-01

We just released Open Dylan 2014.1.

Nix Packages Available - 2014-05-28

Open Dylan is now available in the Nix package manager.

Call for Help! - 2014-01-28

We’re looking for help with various projects!

New release: 2013.2 - 2013-12-23

We just released Open Dylan 2013.2.

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Get Started

Downloading Dylan is easy. Once downloaded, we recommend reading through Introduction to Dylan and exploring some examples.

Learn Dylan

Dylan has a large amount of documentation available:

• Introduction to Dylan:

  A tutorial written for those with solid programming experience in C++ or another object-oriented, static language. It provides a gentler introduction to Dylan than does the Dylan Reference Manual (DRM).

• Dylan Programming Guide:

  A book length Dylan tutorial.

• Dylan Reference Manual:

  The official definition of the Dylan language and standard library.

• Open Dylan Documentation:

  All of the Open Dylan documentation.