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. 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. Unix: make and then ./factor -i=boot.unix-x86.64.image Windows: nmake /f Nmakefile and then factor.com -i=boot.windows-x86.64.image or factor.com -i=boot.windows-arm.64.image for ARM64 You can download a Factor binary from the grid on The nightly builds are usually a better experience than the point releases. The current stable version of Factor uses GTK2 and gtkglext . On Debian 13 “Trixie” and newer Ubuntu releases (25.10 “Questing Quokka” and the 26.04 “Resolute Raccoon” development branch), the gtkglext library is no longer available in the official repositories. Factor's GUI depends on this library, so a fresh install cannot start the GUI on these systems. You can install the libgtkglext1 .deb package from a previous Ubuntu release (e.g. 25.04 “Plucky Pangolin”) and manually add symbolic links expected by Factor: The development branch of Factor has switched from GTK2 to GTK3 for the GUI backend. If you're building or running a binary from the development branch, make sure the GTK3 development library is installed. 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. 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. 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.