# Luavlna, version 0.1l, 2023-06-21

# Introduction

`Luavlna` is a small package for plain LuaTeX and LuaLaTeX. In some languages,
like Czech or Polish, there should be no single letter words at the
line end, according to the typographical norms. There exists some
external commands (like `vlna`) or packages (`encxvlna` for encTeX,
`xevlna` for XeTeX, `impnattypo` for LuaLaTeX).

Other feature of this package is including of non-breakable space after initials,
like in personal names, after or before academic degrees
and between numbers and units (SI and others).

The code is modified version of Patrick Gundlach’s answer on
TeX.sx[^1]. The difference is that it is possible to specify which
single letters should be taken into account for different
languages.
The support for degrees and units was added as well.

# Usage

The usage is simple:

    \input ucode
    \uselanguage{czech}
    %% in the case of luacsplain, use instead:
    %% \chyph
    %% but language code for Czech is different than in LaTeX or normal 
    %% LuaTeX, so you will need to set single letters with somethinh like:
    %% \singlechars{5}{AIiVvOoUuSsZzKk}
    \input luavlna
    \preventsingledebugon
    \input luaotfload.sty
    \font\hello={name:Linux Libertine O:+rlig;+clig;+liga;+tlig} at 12pt 
    \hsize=3in
    \hello
    Příliš žluťoučký kůň úpěl ďábelské ódy. 
    Text s krátkými souhláskami a samohláskami i dalšími jevy 
    z nabídky možností (v textu možnými). 
    
    I začátek odstavce je třeba řešit, i když výskyt zalomení není pravděpodobný.
    
    Co třeba í znaky š diakritikou?
    
    Různé možnosti [v závorkách <i jiných znacích

    Podpora iniciál a titulů: M. J. Hegel, Ing. Běháková, Ph.D., Ž. Zíbrt.

    Podpora jednotek: 100,5 MN\cdot{}s, 100.5 kJ, 200 µA, $-1$ dag, 12 MiB, 1 m$^3$/s.

    \preventsingledebugoff
    \bye


It is also possible to use the package with lua, just use

        \usepackage{luavlna}

in the preamble.

# Commands

    \singlechars{language name}{letters} 

Enable this feature for certain letters in given language. 

Default values:

    %% only Czech and Slovak are supported out of the box
    \singlechars{czech}{AIiVvOoUuSsZzKk}
    \singlechars{slovak}{AIiVvOoUuSsZzKk}

    \compoundinitials{language name}{compounds}

Declare compound letters for given language. Second argument should be comma 
separated list of compound letters, in exact form in which they can appear.

Default values:

    \compoundinitials{czech}{Ch}

##Turning off language switching

By default, language of the nodes is taken into account. If you want to use
settings for one language for a whole document, you can use following command:

    	\preventsinglelang{language name}

##Turning off processing

If you want to stop processing of the spaces in the document you can use
command

    \preventsingleoff

To resume processing, use

    \preventsingleon

## Debugging commands 

    \preventsingledebugon
    \preventsingledebugoff

Insert debugging marks on/off. Default off.

# Authors

Michal Hoftich
Miro Hrončok

# License

Permission is granted to copy, distribute and/or modify this software
under the terms of the LaTeX Project Public License, version 1.3.

[^1]:
    <http://tex.stackexchange.com/a/28128/2891>