Hello Robert,
Thank you for your response.
Yes, I took a look those sites. In the VIM case, the instructions are understandable.
Install VIM
Download ampl-mode for VIM.
Copy and paste the ampl.vim in the syntax file inside VIM was installed
Finally copy
| augroup filetypedetect |
| au BufNewFile,BufRead *.mod setf ampl |
| au BufNewFile,BufRead *.dat setf ampl |
| au BufNewFile,BufRead *.ampl setf ampl |
| augroup END |
In the filetype.vim. I paste it to the end of the existing code in the file.
I don't know if the .mod .dat or .run files must be open with VIM editor. However I opened with VIM but it does not work.
In the ATOM case, I updated and installed the ampl language syntax, but it does not work.
I think that stable editors for AMPL in dark mode are not developed yet.
Regards