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bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code
From: |
Drew Adams |
Subject: |
bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code |
Date: |
Thu, 26 Apr 2012 07:09:06 -0700 |
> we can't say also they are really "free" (even if they
> are sort of free) because they are (will be) all
> let-bounded in some places.
Look up the definition of free variable - see the lambda calculus.
It is always about free _occurrences_ of a variable. Freedom of a variable (not
a great word for it, admittedly) is relative to a given context.
Whether a variable is bound in some outer lambda is not the question. What
matters is whether it is free in some other (e.g. inner) lambda.
X is a free variable in the inner lambda form here, though it is bound in the
outer one, i.e., in the overall expression.
(funcall
(funcall
(lambda (x) (lambda (y) (+ x y)))
42) ; Fn that increments by 42.
3) ; Applied to 3 gives 45.
That is equivalent to this:
(let ((x 42))
(funcall (lambda (y) (+ x y)) 3)
(It's perhaps clearer if you remove all the `funcall' atoms. That will give you
Lisp 1 syntax ~= lambda calculus syntax.)
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Drew Adams, 2012/04/24
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Drew Adams, 2012/04/24
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Drew Adams, 2012/04/24
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Nix, 2012/04/25
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Drew Adams, 2012/04/25
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Thierry Volpiatto, 2012/04/25
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Drew Adams, 2012/04/25
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Thierry Volpiatto, 2012/04/26
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code,
Drew Adams <=
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Drew Adams, 2012/04/26
- bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Thierry Volpiatto, 2012/04/26
bug#11328: 24.1.50; Comment in `dired-copy-file-recursive' code, Stefan Monnier, 2012/04/24