Get started with Mojo🔥 | Modular Docs (2024)

Requirements​

1. Install Mojo​

If you already installed MAX, you can skip to the nextsection because MAX includes Mojo.

The Mojo SDK is available as either a stable build or a nightly build.We strive to release stable builds once a month and release nightly builds asoften as possible (not necessarily every day).

Now you're ready to go.

2. Run code in the REPL​

Now that you've installed Mojo, let's write some code!

First, let's use the MojoREPL,which allows you to write and run Mojo code in a command prompt:

1. To start a REPL session, type mojo in your terminal and press Enter.

2. Then type print("Hello, world!") and press Enter twice(a blank line is required to indicate the end of an expression).

That's it! For example:

$ mojo
Welcome to Mojo! 🔥

Expressions are delimited by a blank line.
Type `:quit` to exit the REPL and `:mojo help repl` for further assistance.

1> print("Hello, world!")
2.
Hello, world!

You can write as much code as you want in the REPL. You can press Enter to start a new line and continue writing code, and when youwant Mojo to evaluate the code, press Enter twice. If there'ssomething to print, Mojo prints it and then returns the prompt to you.

The REPL is primarily useful for short experiments because the code isn'tsaved. So when you want to write a real program, you need to write the code ina .mojo source file.

3. Run a Mojo file​

Now let's write the code in a Mojo source file and run it with themojo command:

1. Create a file named hello.mojo (or hello.🔥) and add the following code:

   fn main():
    print("Hello, world!")
   

   That's all you need. Save the file and return to your terminal.

2. Now run it with the mojo command:

   mojo hello.mojo
   

   It should immediately print the message:

   Hello, world!
   

If this didn't work for you, double-check that your code looks exactly like thecode in step 1, and make sure you correctly installed either MAX(which includes Mojo) or Mojo.

4. Build an executable binary​

Finally, let's build and run that same code as an executable:

1. Create an executable file with the build command:

   mojo build hello.mojo
   

   The executable file uses the same name as the .mojo file, butyou can change that with the -o option.

2. Then run the executable:

   ./hello
   

This creates a statically compiled binary file, so it contains all the code andlibraries it needs to run.

5. Install our VS Code extension (optional)​

To provide a first-class developer experience with features like codecompletion, quick fixes, and hover help, we've created a Mojo extension forVisual StudioCode.

Next steps​

• If you're new to Mojo, we suggest you learn the language basics in theintroduction to Mojo.

• If you want to experiment with some code, clone the Mojorepo to try our code examples:

  git clone https://github.com/modularml/mojo.git
  

  If you installed the nightly build, also checkout the nightly branch:

  git checkout nightly
  

  In addition to several .mojo examples, the repo includes Jupyternotebooksthat teach advanced Mojo features.

• To see all the available Mojo APIs, check out the Mojo standard libraryreference.

If you have issues during install, check our knownissues.

Update Mojo​

To check your current Mojo version, use the --version option:

mojo --version

And compare your version to the latest stable version in the Mojochangelog. Or if you installed a nightly build, look forrelease announcements in this Discordchannel.

If it's time to update, here's what to do:

1. Make sure you have the latest modular CLI:

   • Mac
   • Linux

   brew update \
    && brew upgrade modular
   

2. Update the mojo package:

   • Stable
   • Nightly

   modular update mojo