How to colorize words in a buffer, using type data and position data?

Question

I am writing a plugin for Neovim using Lua.

If I have a text and some predefined arbitrary types, for example:

chita 
wolf
grizzly

types: dog(green), cat(blue), bear(yellow)

And I know positions/indices of words that belong to the types.

What is a better approach to highlight words in the buffer according to the types using Lua?

Update

Looks like I can set custom highlight groups for this purpose:

hi MyDog guifg=red ctermfg=red
match MyDog /wolf/

But I still do not understand how to apply a highlight group not by pattern matching, but by positions in text.

Answer 1

I found matchaddpos function that did allow to solve highlighting programmatically.

Given a text:

wolf, cat black bear,
lion, dog, grizzly,
puma, bear, fox, chita,

I can highlight entries by categories with this function:

local M = {}

M.highlight = function()
  vim.cmd "hi Dogs guifg=green ctermfg=green"
  vim.cmd "hi Cats guifg=yellow ctermfg=yellow"
  vim.cmd "hi Bears guifg=cyan ctermfg=cyan"
  local data = {
    {group = "Dogs", line = 1, pos = 1, len = 4},
    {group = "Cats", line = 1, pos = 7, len = 3},
    {group = "Bears", line = 1, pos = 11, len = 10},
    {group = "Cats", line = 2, pos = 1, len = 4},
    {group = "Dogs", line = 2, pos = 7, len = 3},
    {group = "Bears", line = 2, pos = 12, len = 7},
    {group = "Cats", line = 3, pos = 1, len = 4},
    {group = "Bears", line = 3, pos = 7, len = 4},
    {group = "Dogs", line = 3, pos = 13, len = 3},
    {group = "Cats", line = 3, pos = 18, len = 5}
  }

  for _, datum in pairs(data) do
    local hi_cmd =
      vim.fn.printf('call matchaddpos("%s", [[%d, %d, %d]])', datum.group, datum.line, datum.pos, datum.len)
    vim.cmd(hi_cmd)
  end
end