Allen's lambda syntax proposal
Dave Herman
dherman at ccs.neu.edu
Sun Dec 21 05:09:03 PST 2008
> "^" also has a slight resemblance to the greek lambda, which is the
> reason Haskell uses "\".
As an aside, the circumflex is actually the precursor to lambda:
"We end this introduction by telling what seems to be the story how
the letter 'λ' was chosen to denote function abstraction. In Principia
Mathematica the notation for the function f with f(x) = 2x + 1 is
^
2x + 1.
Church originally intended to use the notation
^
x.2x+1.
The typesetter could not position the hat on top of the x and placed
it in front of it, resulting in
^x.2x + 1. Then another typesetter changed it into λx.2x + 1."
-- H. Barendregt, The Impact of the Lambda Calculus In Logic and
Computer Science [1]
Dave
[1] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.26.7908
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