scheme.fail

Welcome to the home of Loko Scheme, an optimizing Scheme compiler!

• Batteries on the side (Akku.scm).
• Cross-compiles to Linux/amd64, NetBSD/amd64 and bare metal amd64.
• Speaks R6RS Scheme natively and R7RS Scheme as a second language.
• Concurrency based on Concurrent ML.
• Compiled code with reasonable performance.

Screenshots

Download

Loko is available from git:

git clone https://gitlab.com/weinholt/loko.git/

If GitLab is down then there is a mirror at https://scheme.fail/git/loko.git/.

loko-0.13.0.tar.gz (sig) - 2026-06-27

All releases

Loko Scheme is also available from these package repositories:

• Arch Linux AUR
• GNU Guix

  guix install loko-scheme

• Docker

  docker pull weinholt/loko

  docker run --rm -it weinholt/loko

A bootable hard drive image is available. Give it a supported machine with ≥1GB RAM and you get a REPL.

🄯 License

Loko Scheme is licensed under the EUPL-1.2-or-later. This is a copyleft license with a SaaS clause, but which works well for a compiler.

Documentation

The Loko Scheme Developer's Manual [PDF].

Hype-free zone

Loko Scheme is a niche compiler. It is not trying to replace any other compiler. Some ideas for what you can do with it:

• Build statically linked concurrent applications.
• Work on a systems-level language just for fun.
• Systems research.
  • Unikernel experiments.
  • Lock-free kernel experiments.
  • Bare metal Scheme experiments.
  • New userspace-to-kernel interfaces.
• Port to other operating system kernels (FreeBSD, etc).
• Fight the status quo.

Loko Scheme on bare metal comes with the following hardware support:

• Networking (e1000e, rtl8169, rtl8139, eepro100, virtio-net, tuntap) with TCP/IP support.
• Disk (ATA, ATAPI, SCSI, IDE, AHCI) drivers with FAT file system support.
• Video (VESA VBE, Bochs graphics).
• Serial (8250 UART).
• PS/2 keyboard and mouse support.
• USB stack with UHCI, EHCI, HID & mass storage support.

Loko Scheme works on real hardware but it has not been widely tested.

The drivers are used in the bootable disk image.

Bugs and discussion

Please bring bug reports to the mailing list or Loko Scheme on GitLab (preferred). The mailing list is also a great place to discuss Loko Scheme as a user or developer.