Sorry. What I meant is: when you use context.setuphead({'chapter'}, {title="Some text"}) at the Lua end, {'chapter'} and {title="Some text"} (notice "Some text" is a string, not a function) are Lua tables. TeX will print "Some text", but it won't work for context.delayed as it is another table (metatable trickery to allow nesting, I guess). Try: \starttext \startluacode context(type(context.delayed)) \stopluacode \stoptext Long story short: context.cmda(context.delayed.cmdb(something)) will (possibly) work; context.cmdc({key=context.delayed.cmdd(somethingelse)}) won't. Hans and Wolfgang can elaborate in case I've missed something. Jairo :) El lun., 2 de nov. de 2020 a la(s) 22:06, Sylvain Hubert ( champignoom@gmail.com) escribió:

...

as tables like those in setuphead({somehead}, {somesettings}) are actual Lua tables and follow Lua, not TeX, rules But there are lua apis that support delayed TeX like `context.chapter(context.delayed'text')`. Whether or not the function is stored in a table should be theoretically irrelevant. I guess there should be a switch somewhere that let the command recognized delayed function.

On Tue, 3 Nov 2020 at 03:29, Jairo A. del Rio wrote:

...

On the Lua side, you'll have to pass strings so your example works, as tables like those in setuphead({somehead}, {somesettings}) are actual Lua tables and follow Lua, not TeX, rules (see e.g. Lua reference in https://www.lua.org/manual/5.4/ or, better, CLD manual in http://www.pragma-ade.nl/general/manuals/cld-mkiv.pdf):

\starttext

\startluacode

--First example

for m = 1, 3 do

context.setuphead({'chapter'}, {before='hello'})

context.startchapter({title="I'm a chapter!"})

for i = 1, 3 do

context.input("knuth")

end

context.stopchapter()

end

--Second example

--We'll pass some strings to TeX

local nice = "ConTeXt is love, ConTeXt is life"

local somehead = 'chapter'

local sometext = 'vallejo-trilce-es'

context.setuphead({somehead}, {before=nice})

context.startchapter({title=somehead})

context.input(sometext)

context.stopchapter()

\stopluacode

\stoptext

I hope examples help.

Regards,

Jairo :)

El lun., 2 de nov. de 2020 a la(s) 21:09, Sylvain Hubert ( champignoom@gmail.com) escribió:

...

Dear List,

I'm trying to mirror the context command `\setuphead[chapter][before=hello]` into lua with delayed typesetting of 'hello', but `\ctxlua{context.setuphead({'chapter'}, {before=context.delayed'hello'})}` does not have any effect. Could anyone help me on this? Thanks!

Best, Sylvain

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% Hans, sorry for having replied on the wrong channel before. On Tue, 3 Nov 2020 at 09:03, Hans Hagen wrote:

On 11/3/2020 4:05 AM, Sylvain Hubert wrote:

...

...

as tables like those in setuphead({somehead}, {somesettings}) are actual Lua tables and follow Lua, not TeX, rules But there are lua apis that support delayed TeX like `context.chapter(context.delayed'text')`. Whether or not the function is stored in a table should be theoretically irrelevant. I guess there should be a switch somewhere that let the command recognized delayed function. all is possible but not all is reasonable to support .. adding layer upon layed doesn't make it more pretty

Indeed, but still it would be nice to have a complete and consistent interface between tex and lua unless it would harm the functionality.

anyway, chapter (section) titles go tinto a toc table and storing lua delayed function definitions there makes not much sense

It might be helpful in cases like alternative coloring. Writing

"function() local x=1; return function() x=1-x; return ({'black', 'gray'})[x] end end" can be way much easier for lua speakers than digging up a bunch of documentations to figure out whether it's implemented, or how it can be implemented in a language like TeX, or both which is worse. In such cases, it would also be much natural to write 'before=function()..' than 'before=\ctxlua{function()...}` unless, again, the former harms the functionality. Sylvain

again, sorry for replying on the wrong channel. On Wed, 4 Nov 2020 at 17:35, Hans Hagen wrote:

it would harm performance because it involves parsing all values and also ways around cases where the title is "function" (lieral text).

I'm not sure I understand what you mean by literal text "function" here, but in any case isn't it a one-off <1ms cost to parse a function?

"function() local x=1; return function() x=1-x; return ({'black',

...

'gray'})[x] end end" can be way much easier for lua speakers than digging up a bunch of documentations to figure out whether it's implemented, or how it can be implemented in a language like TeX, or both which is worse. Really? I have no clue what that function makec clearer than tex. And one still needs some documentation that explains what it does.

Often there often is a pretty clean way to do it with less code.

For an experienced tex speaker, indeed. But for an average user who just wants to typeset a bit of fancy stuff, programming in tex is probably not the most pleasant thing to do and arguably not the most reasonable either in light of any modern language like lua. Sylvain