Re: general lazy list facility for Emacs Lisp?

[Thierry Volpiatto]

Hi Ted,

Ted Zlatanov <address@hidden> writes:

> On Wed, 23 Mar 2011 17:45:35 +0100 Tassilo Horn <address@hidden> wrote: 
>
> TH> Ted Zlatanov <address@hidden> writes:
>>> Is there a package for general lazy list management in Emacs Lisp?
>
> TH> What's a lazy list?  Something like a LazySeq in Clojure, that is, a
> TH> possibly infinite sequence of things that are only calculated when
> TH> actually consumed ("realized")?
>
> TH> If that's what you mean, I think the answer is no.
>
> Yes, that's what I mean.  In Haskell such lists are simply part of the
> core language; Perl 5 can hack them together with list accessors; Perl 6
> has them in the core too...  I think "lazy list" is a popular term for
> the general facility?  I'm surprised no one has needed them, whatever
> the name :)
Not sure to understand what you want, but maybe have a look at some
ioccur.el functions:

--8<---------------cut here---------------start------------->8---
ELISP> (setq A '(a b c d))
(a b c d)

ELISP> (setq it (ioccur-iter-circular A))

[...]

ELISP> (ioccur-iter-next it)
a
ELISP> (ioccur-iter-next it)
b
ELISP> (ioccur-iter-next it)
c
ELISP> (ioccur-iter-next it)
d
ELISP> (ioccur-iter-next it)
a
ELISP> (ioccur-iter-next it)
b
ELISP> (ioccur-iter-next it)
c
ELISP> (ioccur-iter-next it)
d
ELISP> (ioccur-iter-next it)
a
--8<---------------cut here---------------end--------------->8---
etc...etc...


> Slightly related: is there a general memoization package or standard
> approach to memoizing functions?
>
> Ted
>
>
>

-- 
A+ Thierry
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