How to check whether generator is passed as an argument?
reddit / emacs

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EmilySeville7cfg · 2022-12-28 10:13

I wanna obtain smth (sequence or generator) as a function argument and
if it's a sequence transform it to generator. As I am writting LINQ-
like package for Emacs I need understand how properly work with lazy
things like generators.

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deaddyfreddy · 2022-12-28 10:39

I'm not sure if Emacs lisp has lazy sequences at all

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EmilySeville7cfg · 2022-12-28 10:42

It has yield-s and generators (which I name here as "lazy sequences").
😁

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helm05 · 2022-12-29 07:21

Emacs generators are quite complicated to use.

I generally use simplest things like this:

```
(defun iter-list (seq &optional cycle)
  (let ((lis seq))
    (lambda ()
      (let ((elm (car lis)))
        (setq lis (if cycle
                      (or (cdr lis) seq)
                    (cdr lis)))
        elm))))

(setq foo (iter-list '(a b c d e f)))
(funcall foo)
```

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deaddyfreddy · 2022-12-29 13:32

are you talking about https://nicolas.petton.fr/blog/stream.html ?
It's not an Emacs built-in, but an ELPA package.

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bikenaga · 2022-12-29 15:49

OP is probably referring to the generators described in Sec. 11.6 of
the elisp manual - iter-defun, iter-lambda, and so on.

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EmilySeville7cfg · 2022-12-29 20:39

Yes, I am referring to them. :)