Factor

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.

Getting Started

Building Factor from source

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.

To run a Factor binary:

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

Learning Factor

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.

Documentation

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.

Command Line Usage

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: entry point of <vocab>
        -run=listener    run terminal listener
        -run=ui.tools    run Factor development UI
    -e=<code>        evaluate <code>
    -no-user-init    suppress loading of .factor-rc
    -roots=<paths>   a list of path-delimited extra vocab roots
Enter
    "command-line" help
from within Factor for more information.

You can also write scripts that can be run from the terminal, by putting
#!/path/to/factor at the top of your scripts and making them executable.

Source Organization

The Factor source tree is organized as follows:

vm/ - Factor VM source code (not present in binary packages)
core/ - Factor core library
basis/ - Factor basis library, compiler, tools
extra/ - more libraries and applications
misc/ - editor modes, icons, etc
unmaintained/ - now at factor-unmaintained

Source History

During Factor’s lifetime, source code has lived in many repositories. Unfortunately, the first import in Git did not keep history. History has been partially recreated from what could be salvaged. Due to the nature of Git, it’s only possible to add history without disturbing upstream work, by using replace objects. These need to be manually fetched, or need to be explicitly added to your git remote configuration.

Use:
git fetch origin 'refs/replace/*:refs/replace/*'

or add the following line to your configuration file

[remote "origin"]
    url = ...
    fetch = +refs/heads/*:refs/remotes/origin/*
    ...
    fetch = +refs/replace/*:refs/replace/*

Then subsequent fetches will automatically update any replace objects.

Community

Factor developers are quite active in the Factor Discord server.
Drop by if you want to discuss anything related to Factor or language design in general.

Have fun!