According to Emacs manual, "Aspell, Ispell or Hunspell" integrate automatically with Emacs, it doesn't with Hunspell

[Kyaw]

My Emacs work fine with Aspell but not with Hunspell. I installed Hunspell
and Hunspell-en_US in Arch Linux. Hunspell works fine with LibreOffice and
Firefox. Emacs doesn't detect Hunspell.
How do I make Emacs recognize Hunspell. I'm somewhat new to Emacs. I'm
reading "Learning GNU/Emacs" for now. The book also describes Hunspell will
work fine with Emacs automatically.
I check Emacs Wiki. It say so too.

[Kyaw]

With only Hunspell, pressing M-$ says
Starting new Ispell process /usr/bin/aspell with default dictionary...
Error: No word lists can be found for the language "en_US".

[Eli Zaretskii]

> From: Kyaw <jeckf...@gmail.com>
> Date: Mon, 19 Feb 2018 18:50:11 +0630

>
> My Emacs work fine with Aspell but not with Hunspell. I installed Hunspell
> and Hunspell-en_US in Arch Linux. Hunspell works fine with LibreOffice and
> Firefox. Emacs doesn't detect Hunspell.
> How do I make Emacs recognize Hunspell.

First, make sure Hunspell works from the shell prompt. E.g., type
from the shell command line "hunspell SOME-FILE" and see that you get
Hunspell's UI with the first misspelled word highlighted.

If that works, then your problem could be that by default Emacs looks
for the spellers in this order:

. aspell
. ispell
. hunspell

So if you have both Aspell and Hunspell installed, customize the
variable ispell-program-name to have the value "hunspell". You need
to perform this customization _before_ you invoke ispell-word or
ispell-buffer the first time.

[Kyaw]

Solved. Thank you, eli! From 2000 onward, you had been an active
contributor to this list.