Lambda Logo Tour

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A Lambda Logo Tour

(and why LISP languages using λ as logo should not be looked upon kindly)

Xah Lee, 2002-02, ..., 2010-09-25

Dear lispers,

The lambda character λ, always struck a awe in me, as with other mathematical symbols. In my mind, i imagine that those obscure math symbolism are etched in stone by god. A salient example is the book cover Concrete Mathematics by Ronald Graham et al. amazon

book cover of Concrete Mathematics

Book cover of Concrete Mathematics.

Here we see the summation sign ∑ etched in stone. The summation sign happens to be my favorite math symbol. (chosen as my website signet: signet)

These symbols are not to be trifled with. If anyone puffs in as much half a snicker, i wish god strikes a thunder upon their impudence.

Promote your logo with these custom promotional items for your brand.

The Greek lambda symbol is used in a branch of logic called lambda calculus. The theories of lambda calculus is what functional languages are based on, thus many functional language's logo feature the lambda. Here is a collection of functional language's logos involving the lambda.

✻ ✻ ✻

Mit Scheme lisp logo 2010

MIT Scheme's logo.

MIT Scheme is a grand daddy of Scheme lisp. Its logo features a recursive shield with lambda.'s logo's logo.

This logo has a modern look. It is a simple lambda inside a O figuration. Though, i was told this “O” is supposed to be a pair of parenthesis.

PLT Scheme logo

PLT Scheme's logo.

PLT Scheme's logo, notable is the red/white/blue coloring scheme. PLT Scheme changed its name to Racket in 2010-06. Home page:


MzScheme's logo.

MzScheme is part of PLT Scheme. The logo features a lambda besides a Chinese character 文 (wen2). The character means written language.

Common Lisp HTTP server logo

Common Lisp HTTP server web badge. Quite lame and unprofessional.

Scheme Shell logo

Scheme shell scsh logo is a lambda inside a bivalve, perhaps most florid of the bunch:

Haskell language logo

Haskell language logo in 2002.

Haskell logo

Haskell's new logo, inaugurated in 2003-05. It is designed by Fritz Ruehr. Superb.

It is made of 5 math symbols revolving around a big lambda. The symbols are: right arrow →, inverted A ∀, double right-pointing angle bracket ≫, double colon ::, double right arrow ⇒, and lambda λ. The right arrow → signifies transformation. The inverted A ∀ signifies “for all”. The double angle ≫ signifies free from disorder. The double colon :: signifies exactitude. The double right arrow ⇒ signifies generality. Finally, the lambda λ signifies functionality.

Haskell web badge Haskell web badge

Two web badges for Haskell. (For detail, see Haskell Logo.)

Haskell logo7000

Haskell's new logo of 2009.

This logo's concept is based on ASCII art by Darrin Thompson, and interpreted by Jeff Wheeler. It is a result of public logo contest. For detail, and many quality logo entries, see Source.

Hugs98 logo

The Haskell interpreter Hugs98 features a 3D lambda with projected shadow

Yale Haskell logo Yale Haskell bullfrog

Yale Haskell project used a logo that features symbols in lambda calculus including the lambda, and also a bullfrog head. Quite funny and beautiful. (the bullfrog logo origin is explained at the bottom. i.e. that of parody to Yale's bulldog logo)

cover of Structure and Interpretation of Computer Programs

The book cover of Structure and Interpretation of Computer Programs, by Harold Abelson, Gerald Jay Sussman, features a wizard and witch gesticulating with prominent lambda, and a monster foot of the table showing.

I love these lambda-featuring logos. However, i have a complaint. As most of you know, lisp languages are not purely functional languages. Subroutines in lisps easily have side-effects, and sometimes non-functional programing methodologies such as OOP are actually encouraged in lisp. As most of you know, the lambda symbol chosen by functional languages is to signify no side-effects. In this respect, i find the lisp languages not totally deserving the use of lambda in their logo. As i have expressed before, mathematical symbols are not to be trifled with, and the Schemers have tainted my mathematics, strictly speaking.

Although i have this minor objection with lispers using the lambda symbol, but overall i think the lispers and i share a more important common goal. That is, to kill all imperative programing ignoramuses of the world. Once the unix and C and Perl and otherwise idiots are all dead, then i'll formally raise my objection about Lisper's unfit borrowing of the lambda symbol.

✻ ✻ ✻

Addendum, 2003-05, ..., 2010-09-25


PFP logo, by Martin Erwig.

The PFP library for Haskell features a lambda disguised as a histogram. One of the most well-designed among lambda logos. (“A Probabilistic Functional Programming Library for Haskell” by Martin Erwig and Steve Kollmansberger, 2005.

FC++ logo

Logo for FC++ by Brian Dickens.

Someone has written a C++ library for functional programing, called FC++. (by Brian McNamara and Yannis Smaragdakis, 2003) Website:

Scheme Chicken logo

Chicken Scheme logo.

Chicken Scheme features a logo that is a lambda inside a hen silhouette. (by Felix L Winkelmann, at

This is getting silly and disrespectful.

chicken scheme logo chicken4-low

Chicken's new logos, by Moe Aboulkheir et al. Left as of 2007-03, right as of 2009-06.

I prefer the original yellow hen logo. This new modern looking logo lost it's chicken attraction. You can't easily tell what bird it is, and the funky lambda takes some tech geeking to recognize. The original logo of the fat hen signifies birth, with lambda right in its tummy.

For some history of CHICKEN scheme's logo, see Source.

Qi logo

A Qi (programming language) logo designed by yours truely. For detail, see: Qi Language Logo.


Logo of Clojure, a new Lisp lang in Java Virtual Machine. The logo is designed by Tom Hickey with input from Rich Hickey. A SVG version is here: File:Clojure-glyph.svg

Non-Lambda Logos

Here's some collection of lisp logos that does not involve lambda.

LISP logo

Classic twisty lisp. For different sizes and SVG format, see LISP Logo.

CLforJava logo

CLforJava logo.

CLforJava is a Common Lisp implementation on Java Virtual Machine. Home page:

Clozure Common Lisp logo

Clozure Common Lisp logo.

Clozure Common Lisp is formally OpenMCL, which is derived from Macintosh Common Lisp (MCL). Home page is at:

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