Factor is a concatenative, stack-based programming language with high-level features including dynamic types, extensible syntax, macros, and garbage collection. On a practical side, Factor has a full-featured library, supports many different platforms, and has been extensively documented.

The implementation is fully compiled for performance, while still supporting interactive development. Factor applications are portable between all common platforms. Factor can deploy stand-alone applications on all platforms. Full source code for the Factor project is available under a BSD license.

If you have a build environment set up, then you can build Factor from git. These scripts will attempt to compile the Factor binary and bootstrap from a boot image stored on factorcode.org.

To check out Factor:

• git clone https://github.com/factor/factor.git
• cd factor

To build the latest complete Factor system from git, either use the build script:

• Unix: ./build.sh update
• Windows: build.cmd
• M1 macOS: arch -x86_64 ./build.sh update

or download the correct boot image for your system from https://downloads.factorcode.org/images/master/, put it in the factor directory and run:

• Unix: make and then ./factor -i=boot.unix-x86.64.image
• Windows: nmake /f Nmakefile x86-64 and then factor.com -i=boot.windows-x86.64.image

Now you should have a complete Factor system ready to run.

Factor does not yet work on arm64 cpus. There is an arm64 assembler in cpu.arm.64.assembler and we are working on a port and also looking for contributors.

More information on building factor and system requirements.

You can download a Factor binary from the grid on https://factorcode.org. The nightly builds are usually a better experience than the point releases.

• Windows: Double-click factor.exe, or run .\factor.com in a command prompt
• macOS: Double-click Factor.app or run open Factor.app in a Terminal
• Unix: Run ./factor in a shell

A tutorial is available that can be accessed from the Factor environment:

"first-program" help

Take a look at a guided tour of Factor:

"tour" help

Some demos that are included in the distribution to show off various features:

"demos" run

Some other simple things you can try in the listener:

"Hello, world" print

{ 4 8 15 16 23 42 } [ 2 * ] map .

1000 [1..b] sum .

4 <iota> [
    "Happy Birthday " write
    2 = "dear NAME" "to You" ? print
] each

For more tips, see Learning Factor.

The Factor environment includes extensive reference documentation and a short "cookbook" to help you get started. The best way to read the documentation is in the UI; press F1 in the UI listener to open the help browser tool. You can also browse the documentation online.

Factor supports a number of command line switches:

Usage: factor [Factor arguments] [script] [script arguments]

Common arguments:
    -help            print this message and exit
    -i=<image>       load Factor image file <image> (default factor.image)
    -run=<vocab>     run the MAIN: en