nvim: Dynamically source colorscheme from file

Neovim will source the `colorscheme.lua` file in its state directory on
startup, as well as whenever the file contents are changed.
This allows any colorscheme definition to be put into the file and vim
will apply it as soon as the file contents change.

nvim/.config/nvim/lua/look.lua

@@ -7,10 +7,28 @@ vim.api.nvim_set_var('gruvbox_italic', 1)
 vim.api.nvim_set_var('one_allow_italics', 1)
 vim.api.nvim_set_var('pencil_terminal_italics', 1)
 
-function B16theme(theme)
-    local base16scheme = b.themes[theme]
-    b(base16scheme, true)
+local colorsfile = vim.fn.stdpath('state') .. '/colorscheme.lua'
+local function source_colors()
+    if vim.fn.filereadable(colorsfile) == 1 then
+        vim.cmd("source " .. colorsfile)
+    end
 end
 
--- set the default colorscheme
-B16theme('eighties')
+-- source colors automatically from colorscheme file on change
+local w = vim.loop.new_fs_event()
+local function on_change(err, fname, status)
+    source_colors()
+    w:stop()
+    Watch_file(fname)
+end
+function Watch_file(fname)
+    local fullpath = vim.api.nvim_call_function('fnamemodify', { fname, ':p' })
+    w:start(fullpath, {}, vim.schedule_wrap(function(...)
+        on_change(...)
+    end))
+end
+
+-- set on startup
+source_colors()
+-- and watch continuously
+Watch_file(colorsfile)