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Comment by mattmcknight | Hacker News Reader

Yes, but don't overlook the "Let x =" syntax of mathematics. Programming has just dropped the "let". So, really there is a choice to be made about how to resolve that ambiguity in a language parser. Visual Basic has the nice case of A = B = C setting A equal to the boolean expression B = C.

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Let in mathematics doesn't really work that way. It's more general.

"Let <boolean expression>" means that the world gets set up so that the boolean expression is true.

Examples:

Let x=4

Let epsilon>0

Let a in A

There's very interesting work on providing an iteration construct like this in a programming language.

http://www.cs.cornell.edu/Projects/jmatch/

Old versions of BASIC used LET for assignment, but Microsoft BASIC and other BASICs of that era dropped it as being unnecessary.

Not completely, Lisp uses let for variable bindings...

  (let ((x 5)
        (y 10))
    (+ x y))

  => 15

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