Hi, Hans. I've got a question. Negative steps are treated as positive:

\starttext
\expandedloop 10 0 -2 {\the\currentloopiterator\ }
\stoptext

gives

0 2 4 6 8 10

Is this expected behavior? If so, it would be fine to have something more alike to MetaPost's "for ... step ... until" loop. Thank you in advance.

Regards,

Jairo

El vie, 3 dic 2021 a la(s) 09:29, Hans Hagen via ntg-context (ntg-context@ntg.nl) escribió:
Hi,

a new upload

- some keywords renamed in the engine and therefore more split between
mkiv and lmtx (hopefully i included all files) .. if something doesn't
work any more it might be because i missed a rename.

- i finally decied that it does make sense to have native loops at the
primitive level (after all, metapost as macro language also has them)
and although much is possible in macros it doesn't mean we have to do it
the (often ugly and showing-off-by-abusing-side-effects way).

We have just a constructor:

   \unexpandedloop      1 100 1 {.}

and a fully expandable one for e.g. use in \edef:

   \expandedloop        1 100 1 {.}

plus an also fully expandable one for anywhere but with potential side
effects (out of order local loops):

   \localcontrolledloop 1 100 1 {.}

complemented by a few status primitives (integers, use \the or \number
to serialize them):

   \currentloopiterator
   \currentloopnesting

and a quitter that aborts at the next iteration:

   \quitloop

as usual it's experimental for a while. Among the rationales are 'less
tracing clutter', 'performance' and 'more natural primitive tex coding'
(but that one is personal).

Hans

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