Re: Lexical let and setq

[Richard Stallman]

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    The primary reason I have seen the (let (foo) (setq foo ...)) idiom is
    in looping code.

I have written code that way simply to make it clearer to read.

      The way I would normally try to avoid this idiom in
    most FP languages

We should not try to avoid it.  We should make it work
just as efficiently as if it were written the other way.

With lexical scope, it is not hard to determine that the lexical
variable's value is never used until after the setq.  Then it
can be compiled as immutable.

We suggest Emacs Lisp as a path for non-programmers to learn to
program, so we need to encourage styles that are natural.  That means
loops, not tail recursion.  Tail recursion is harder to read.

-- 
Dr Richard Stallman
President, Free Software Foundation
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