Re: Closures - do you understand them well?

[Emanuel Berg]

Michael Heerdegen wrote:

>> (let ((i 0)
>>       (m (lambda (i)
>>            (lambda () i)))
>>       funs)
>>   (while (< i 100)
>>     (push (funcall m i) funs)
>>     (cl-incf i))
>>   (mapcar #'funcall funs))
>
> Yes, I think one can do this (the argument variable
> i shadows the variable of the same in the `let', but it also
> exists to conserve the value from the outside i so one can
> argue that it's ok to use the same name - it's semantically
> not incorrect anyway). Nice solution.

Okay so now it works for me as well, maybe some encoding in
messed up evaluation ...

>> (let ((i 0)
>>       funs)
>>   (while (< i 100)
>>     (let ((j i))
>>       (push (lambda () j) funs))
>>     (cl-incf i))
>>   (mapcar #'funcall funs))
>
> This is the trick that is used in the implementation of
> `dolist': create a binding that lives only inside the
> evaluation of the body of the loop in one iteration step.

Same, works.

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