Download uLisp

Download the latest version of uLisp here:

Version 1.5 - 24th January 2017

or get it from GitHub at

Changes in Version 1.5

uLisp Version 1.5 adds support for strings, allowing you to write programs that prompt the user for input, or manipulate strings. It includes the string functions subseq for extracting a substring from a string, string= for comparing strings, length for finding the length of a string, and stringp for testing for strings.

It also includes several minor bug fixes.

Installing uLisp

This download is a text file. To compile it in the Arduino IDE either save it as a text file and rename it to a .cpp file, or cut and paste the text into a new empty project file.

Older versions

Version 1.4

uLisp Version 1.4 adds a built-in program editor edit that lets you step through a function definition, editing it a bit at a time, using a set of simple single-key editing commands you type at the keyboard; see Using the program editor.

It also includes room, which returns the number of free Lisp cells remaining.

uLisp Version 1.4 - 18th October 2016

Version 1.3

  • Adds setf which allows you to modify lists in place, allowing you to use lists as index-addressible arrays, and use association lists for efficient data storage.
  • The other in-place operations pushpopincf, and decf have been extended in the same way.
  • Fixes two bugs that affected append with null arguments, and with-spi.

uLisp Version 1.3 - 24th July 2016

Version 1.2

  • A simple, unified I2C and SPI interface using read-byte and write-byte to transmit data via the appropriate interface, and streams to identify which interface is being used. For more details see I2C and SPI serial interfaces.
  • The bitwise logical operators logandlogiorlogxorlognotlogbitp, and the bitwise shift operator ash.
  • 1.2a included a minor change that fixed a subtle problem affecting dolist.

uLisp Version 1.2a - 18th June 2016

Version 1.1

  • save-image and load-image allow you to save the uLisp image to EEPROM and reload it.
  • #x#o, and #b allow you to enter numbers in hexadecimal, octal, or binary respectively.
  • note now supports the ATmega1284P.

uLisp Version 1.1 - 6th June 2016

Version 1.0

Version 1.0 was the first version of uLisp.

uLisp Version 1.0 - 25th May 2016

Test suite

The following file contains a test suite I use for testing each release of uLisp. You may find this useful if you are porting uLisp to another platform:

Test suite