What Does Qi Mean?

Qi is a functional programming language that is well suited for mathematical evaluations and the programming of mathematical equations and functions. Qi offers the advantages of pattern matching, lambda calculus consistency, static type checking and optional lazy evaluation.


Qi is written in Common Lisp generating efficient type secure programs that may run on any machine. It was developed by Dr. Mark Tarver and first released under GPL in 2005 but this was deemed unsuitable for commercial applications. Qi II is made available under two proprietary licenses: one for developing closed source, proprietary software and the other is for educational and personal use.

Techopedia Explains Qi

Qi was first released in April, 2005. Qi defines types using logical notation of sequent calculus and under Qi’s interpretation, this type notation can be considered as a Turing complete language. Through this notation, Qi can assign extensible type systems into Common Lisp Libraries, which is quite a powerful feature of the language.

The L21 project was meant to modernize Lisp so that it can keep up with the ever changing needs of computing in the 21st century; hence the name. The project was launched because Lisp had some challenges which barred its way for wider adoption. Dr. Tarver identified these challenges specifically as Common Lisps lack of pattern-matching, procedural contamination, inconsistency with respect to lambda calculus and lack of static typing.


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Margaret Rouse

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.