[plt-scheme] Why "lambda"?

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Tue May 26 11:09:57 EDT 2009

The story is that in the 10s and 20s, mathematicians and logicians  
used ^ as a notation for set abstraction, as in ^i : i is prime.  
Church used ^` (i.e., a primed version of this symbol) for function  
abstraction, because functions are just sets with extra properties.  
The first type setter/secretary read it as λ and Church was fine  
with. True or not? I don't know but it's fun.

On May 26, 2009, at 10:53 AM, Todd O'Bryan wrote:

> After getting the lambda chair emails, I had to show it to my
> students. (After flipping it horizontally, of course.)
> One of the students asked, "Why is it lambda and not some other  
> Greek letter?"
> Does anyone know if Church had anything in mind for lambda to stand
> for, or was it just an arbitrary choice?
> Todd
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