Download and install uLisp
Release 4.8
This release of uLisp features an improved implementation of streams which is more efficient, and provides the additional benefit that you can extend uLisp by defining custom streams in an Extensions File. For details see Streams.
Downloading uLisp
There are now five actively maintained versions of uLisp. Download the correct one for your platform:
AVR version
Download the AVR version of uLisp for AVR platforms with at least 64 Kbytes of program memory, including the Arduino Mega 2560, ATmega1284, and AVR DA/DB-series platforms:
AVR Release 4.8a - 7th July 2025
or get it from GitHub at https://github.com/technoblogy/ulisp.
AVR-Nano version
Download the AVR-Nano version for AVR platforms with 32 or 48 Kbytes of program memory, such as the Arduino Uno, Arduino Nano, and Arduino Nano Every:
AVR-Nano Release 4.7 - 9th November 2024
or get it from GitHub at https://github.com/technoblogy/ulisp.
ARM version
The ARM version of uLisp supports the Arduino Zero, Arduino MKRZero, Adafruit M0 boards, Adafruit M4 boards, Adafruit PyBadge/PyGamer, Adafruit nRF52840 boards, Adafruit Clue, BBC Micro Bit, Calliope mini, MAX32620FTHR, Teensy 4.0/4.1, RP2040/RP2350-based boards, and Arduino Uno R4 boards:
ARM Release 4.8c - 31st May 2025
or get it from GitHub at https://github.com/technoblogy/ulisp-arm.
ESP version
Download the latest ESP version of uLisp for the ESP32 platforms here:
ESP Release 4.8d - 30th June 2025
or get it from GitHub at https://github.com/technoblogy/ulisp-esp.
RISC-V version
Download the latest RISC-V version of uLisp for the Sipeed Maixduino, MAiX One Dock, and MAiX BiT boards here:
RISC-V Release 4.7 - 5th November 2024
or get it from GitHub at https://github.com/technoblogy/ulisp-riscv.
Commented versions
Commented versions are available from the above GitHub links which are identical to the above source files, but include comments to explain the C functions.
Installing uLisp
The download is a single text file. To compile it in the Arduino IDE either save it as a text file and rename it to a .ino file, or copy and paste the text into a new empty project file. You can download the latest Arduino IDE from arduino.cc.
Select the correct Board option for your platform on the Tools menu, select the USB port from the Port menu, and upload uLisp. You should then be able to select Serial Monitor from the Tools menu, and interact with uLisp as described in Using uLisp.
Many of the board descriptions give specific installation instructions for that platform.
If you're using uLisp with the Arduino IDE on Debian or OpenBSD see these threads on GitHub: https://github.com/technoblogy/ulisp/pull/2 and https://github.com/technoblogy/ulisp/pull/22.
Note that saved images are not generally compatible between different releases of uLisp.
Compile options
The uLisp sources provide the following compile options:
| Option | Default | Description |
| checkoverflow * | enabled | Generates an error if underflow/overflow occurs in arithmetic operations. |
| resetautorun | disabled | Loads, and optionally runs, an image using load-image on reset. |
| printfreespace | enabled | Prints the number of free objects before the uLisp prompt. |
| printgcs | disabled | Prints the amount of space reclaimed after each garbage collection. |
| sdcardsupport | disabled | Provides SD card support using with-sd-card. |
| gfxsupport † | disabled | Provides graphics extensions for use with a suitable display. |
| lisplibrary | disabled | Evaluates the Lisp definitions provided in the Lisp Library on reset. |
| assemblerlist ¶ | enabled | Generates an assembler listing from defcode. |
| lineeditor | disabled | Provides a line editor for use when using uLisp from a terminal. |
| vt100 | disabled | Provides parenthesis matching on VT100-compatible terminals. |
| extensions ‡ | disabled | Includes Lisp functions defined in a separate extensions file. |
| streamextensions ‡ | disabled | Includes streams defined in a separate extensions file. |
* Only applicable to the integer-only versions: currently AVR and AVR-Nano.
† Only applicable to the versions with graphics extensions; currently ARM, ESP, and RISC-V.
¶ Only applicable to versions with defcode; currently ARM, RISC-V, and AVR.
‡ Not applicable to the AVR-Nano version.
Other platforms
These versions are also available, but are not currently up to date with the newer features:
MSP430 version
Download the version of uLisp for the Energia MSP430 platforms here:
MSP430 Release 2.7c - 20th June 2019
or get it from GitHub at https://github.com/technoblogy/ulisp-msp430.
STM32 version
Download the STM32 version of uLisp for the Maple Mini and Blue Pill platforms here:
STM32 Release 3.0b - 11th January 2020
or get it from GitHub at https://github.com/technoblogy/ulisp-stm32.
Older releases
See Older releases.
Test suites
The following files contains test suites I use for testing each release of uLisp. You may find these useful if you are porting uLisp to another platform:
Test suite - 8/16-bit version (AVR uLisp)
Test suite - 32-bit version (ARM, ESP, and RISC-V uLisp)
Test suite - Floating point (ARM, ESP, and RISC-V uLisp)