Dafny is a programming language with a program verifier. As you type in your program, the verifier constantly looks over your shoulders and flags any errors. This github site contains these materials:

• sources
• binary downloads for Windows, macOS, GNU/Linux, and FreeBSD
• the issue tracker
• the wiki, including frequently asked questions

Documentation about the dafny language and tools is located here. A reference manual is available both online and as pdf. (A LaTeX version can be produced if needed.)

You can ask questions about Dafny on Stack Overflow or participate in general discussion on Dafny's .

The easiest way to try out Dafny is to install Dafny on your own machine in Visual Studio Code and follow along with the Dafny tutorial. You can also download and install the Dafny CLI if you prefer to work from the command line.

Here are some ways to get started with Dafny:

• 4-part course on the Basics of specification and verification of code:
  • Lecture 0: Pre- and postconditions (19:08)
  • Lecture 1: Invariants (20:56)
  • Lecture 2: Binary search (21:14)
  • Lecture 3: Dutch National Flag algorithm (20:33)
• New overview article: Accessible Software Verification with Dafny, IEEE Software, Nov/Dec 2017
• Online tutorial, focusing mostly on simple imperative programs
• 3-page tutorial notes with examples (ICSE 2013)
• Dafny Quick Reference
• Language reference for the Dafny type system, which also describes available expressions for each type
• Cheatsheet: basic Dafny syntax on two pages
• Dafny Reference Manual [html] [pdf]
• Dafny libraries, a standard library of useful Dafny functions and lemmas
• Dafny Power User
• Videos at Verification Corner

The language itself draws pieces of influence from:

• Euclid (from the mindset of a designing a language whose programs are to be verified),
• Eiffel (like the built-in contract features),
• CLU (like its iterators, and inspiration for the out-parameter syntax),
• Java, C#, and Scala (like the classes and traits, and syntax for functions),
• ML (like the module system, and its functions and inductive datatypes), and
• Coq and VeriFast (like the ability to include co-inductive datatypes and being able to write inductive and co-inductive proofs).

• Haskell-to-Dafny translator, by Duncan White
• Vim-loves-Dafny mode for vim, by Michael Lowell Roberts
• Boogie-Friends Emacs mode

To enforce some basic style conventions, we've adopted pre-commit. We're using their default hooks. When you clone Dafny, install pre-commit as per the instructions. For example, on macOS you do

$ brew install pre-commit

Then run

$ pre-commit install

This will install pre-commit hooks in your .git/hooks directory.

Dafny itself is licensed under the MIT license. (See LICENSE.txt in the root directory for details.) The subdirectory third_party contains third party material; see NOTICES.txt for more details.