Try this to help troubleshoot the issue:
Check the location where you have downloaded the color proton.vim file.
On Linux, the system default will be something like
On MSWindows, the system default will be something like
C:\Program Files (x86)\Vim\vim74\colors\
You could also try setting up a home directory for colors:
$HOME/.vim/colors on Linux, or
$HOME/vimfiles/colors on MSWindows.
See if the color scheme shows up outside of your
Restart vim, then per this StackOverflow post, type
:colorscheme then Space followed by CTRLd
This should list your colorscheme along with all other color schemes.
Note: CTRLd returns one list which shows all color schemes.
If you use
:colorscheme then Space followed by TAB you will iterate over the list of color schemes, one at a time, each time you press TAB
You can also see this behaviour if you use
:colorscheme then Space followed by CTRLi ; you will iterate over the list of color schemes, one at a time, each time you press CTRLi
When I troubleshoot an issue like this, I prefer CTRLd so I may see the entire list at once.
to return the name of the current colorscheme in use by vim
If you've added it to
to confirm which .vimrc file is being loaded by vim, type
This will show you the path to the
the path to the current colorscheme loaded,
and all scripts sourced so far.
This file will be
~\_vimrc on MSWindows.