Warning: this is an htmlized version!
The original is across this link,
and the conversion rules are here.
Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio
> dofile "abbrevs.lua"
> abbr = Abbrevs.new():add("->", "\\to ", "!", "_")
> = abbr
{ "!"="_",
  "-"=0,
  "->"="\\to "
}
> = abbr:unabbrev "a->b ! c->d<--e->"
a\to b _ c\to d<--e\to 
>