support please: sile w/ fennel (for lua)

[reuleaux]

I have successfully installed sile - and can use it to typeset this little document for example:
the lua script therein being one of the first examples from the sile manual:

\begin{document}
Hello SILE!
\begin{script}
  for i=1,10 do
    SILE.typesetter:typeset(i .. " x " .. i .. " = " .. i*i .. ". ")
    SILE.typesetter:leaveHmode()
    SILE.call("smallskip")
  end
\end{script}
\end{document}

Now I would prefer to use fennel instead of lua - cf.
https://fennel-lang.org/
And according to
https://fennel-lang.org/setup#embedding-fennel
it should be possible to use fennel from sile somehow (!?) like this:

\begin{document}
Hello SILE!
\begin{script}
  require("fennel").install().dofile("main.fnl")
  ...fennel code...
\end{script}
\end{document}

assuming fennel is properly installed - but this is my question, really:
following the https://fennel-lang.org/setup#embedding-fennel instructions I can e.g. clone fennel

cd ~/tmp && git clone --depth 1 -b 1.3.1 https://git.sr.ht/~technomancy/fennel

and then make it

cd ~/tmp/fennel && LUA=lua5.4 make

this creates a ~/tmp/fennel/fennel.lua for me.
but how do I tell sile to use this ~/tmp/fennel now ?

Or could I use luarocks for fennel? - If I do

luarocks install --lua-version=5.4  fennel

I get a fennel executable, not a fennel.lua file, however.

I am fairly experienced in computing in general, but with regards to lua / luarocks only a beginner,
thus bear with me.

Any help in this regard welcome. - Thanks - A'

[reuleaux]

To answer my own question: I got it working (at least with a separat main.fnl file, cf. below) - like so:

(I am installing everything as a normal user rx (/home/rx), except sile's luarocks deps - those as root)

clone & make fennel

cd ~/tmp && git clone --depth 1 -b 1.3.1 https://git.sr.ht/~technomancy/fennel
cd ~/tmp/fennel && LUA=lua5.4 make

(there should be a fennel.lua file then in ~/tmp/fennel)

then configure/make/install sile - with fennel in mind:

configure 1st time - just so that sile-dev-1.rockspec is created:

cd ~/tmp/sile && LUA=/usr/bin/lua5.4 ./configure --prefix=/home/rx/opt/sile

install lua deps (this step as root):

# cd /home/rx/tmp/sile && luarocks install --lua-version=5.4 --only-deps  sile-dev-1.rockspec

now do the real configure - and as for fennel: use LDFLAGS

cd ~/tmp/sile && LUA=/usr/bin/lua5.4 ./configure LDFLAGS="-L/home/rx/tmp/fennel" --prefix=/home/rx/opt/sile --with-system-luarocks

make & inscall

cd ~/tmp/sile && make
cd /tmp/sile && make install

then have a sample file foobar.sil

\begin{document}
Hello SILE!

\begin{script}
  require("fennel").install().dofile("main.fnl")
\end{script}

\end{document}

and next to it a file main.fnl:

(each [i value (ipairs ["b" "b" "c"])]
      ;; (print index value)
      (SILE.typesetter:typeset (.. i " x " i " = " (* i i)))
      (SILE.typesetter:leaveHmode)
      (SILE.call "smallskip")
      )

This (sile foobar.sil) creates a foobar.pdf as attached.
foobar.pdf

I yet have to find out how to just use fennel - without a separate main.fnl - somehow like this ??:

\begin{document}
Hello SILE!
\begin{script}
  require("fennel").install().(each [i value (ipairs ["b" "b" "c"])]
                                                   (SILE.typesetter:typeset (.. i " x " i " = " (* i i)))
                                                   (SILE.typesetter:leaveHmode)
                                                   (SILE.call "smallskip")
                                               )
\end{script}

\end{document}

Maybe fennel could become a first class sile citizen ?

What always works, of course: use fennel as a converter:

fennel file.fnl

to create a file.lua - and this could be sile-lua file

but I was interested here really, how to integrate fennel in a (normal) .sil file.

Thanks, A'

[alerque]

I'm not at home and have spotty access and time for a few weeks, but off the top of my head it should be possible to simplify this quite a bit. I would probably write a LuaRocks package as a 3rd party module for SILE that copies most of the current lua inputter code but adds the Fennel preprocessor step. Then post it to LuaRocks with a dependency on fennel. That done a simple "luarocks install fennel.sile" should get things going, and in a document you could then \use[module=fennel] to load the inputer, after which you could have a \fennel{...} command available to use in place of \lua{} (of which \script{} is just an alias).

[reuleaux]

Great! - And thanks for getting back to me about this. - I will have a look (and a stab) at writing
a loarocks sile package for fennel then sometime - not immediately though: I am busy myself, and have only just started reading the sile manual, and I prefer to continue reading / progressing step by step: but I see that in the later chapters
of the manual writing a sile package is explained.

[Omikhleia]

I agree with @alerque that this is best addressed as a 3rd-party package. The fennel.lua file is above 5KLoc and 230kB of machine-generated code, which is quite a lot for such a niche use case, without clear rationale (except a vague user preference for Lisp-like syntax?) Besides, it's certainly not the task of the SILE core distribution to maintain such an embedding and keep track of versions and updates for such a niche language - not even mentioning investigating potential bugs.

On the technical aspect, however, I don't think an inputter is even needed, neither the need for reserving a \fennel command as SIL pass-through exception... Raw command handlers should be largely sufficient and have the necessary API, and provided one does read the manual up to the relevant chapter before asking how to implement things, one should find there the needed information. I would suggest starting with this solution...

As for being busy, aren't we all?

But bear with me, the above suggestion is then at most 15-20mn of coding for an experienced senior developer :)
Really? Aye, just did it. This said, I will close this issue and move it to the discussions (Q&A). I'll post my PoC code there.

[Omikhleia]

Here you go for a working Proof of Concepts, with bells and whistles (complete folder tree with package, example and even README)

fennel.sile.zip

Uncompress it somewhere, move to that folder, and enjoy.
N.B. requires SILE 0.14.10 -- see in-code comment if you need to try with an earlier 0.14.x...
(EDIT: Just checked that comment is all what is needed for at least 0.14.9)

[reuleaux]

Many thanks for this fennel/sile solution of yours - looks great to me!
(And yes: I do prefer Lisp over original Lua - and I am busy developing some
fashion concepts btw.)

[Omikhleia]

Thanks for the feedback @reuleaux
I'm glad my PoC answers your question and looked as great as you expected!
If you are indeed satisfied with it, can please click "Mark as answer" on the discussion where I provided my solution?
Not only will I be credited for the answer, but other readers with a similar interest will know where too look.
Thanks in advance.