Add sample prompt for vi mode

share/functions/fish_vi_prompt.fish

@@ -0,0 +1,48 @@
+function fish_vi_prompt_cm --description "Displays the current mode"
+  echo -n " "
+  switch (bind_mode)
+    case default
+      set_color --bold --background green white
+      echo "[C]"
+    case insert
+      set_color --bold --background red white
+      echo "[I]"
+  end
+  set_color normal
+end
+
+function fish_vi_prompt --description "Simple vi prompt"
+
+	# Just calculate these once, to save a few cycles when displaying the prompt
+	if not set -q __fish_prompt_hostname
+		set -g __fish_prompt_hostname (hostname|cut -d . -f 1)
+	end
+
+	if not set -q __fish_prompt_normal
+		set -g __fish_prompt_normal (set_color normal)
+	end
+
+	switch $USER
+
+		case root
+
+		if not set -q __fish_prompt_cwd
+			if set -q fish_color_cwd_root
+				set -g __fish_prompt_cwd (set_color $fish_color_cwd_root)
+			else
+				set -g __fish_prompt_cwd (set_color $fish_color_cwd)
+			end
+		end
+
+		echo -n -s "$USER" @ "$__fish_prompt_hostname" ' ' "$__fish_prompt_cwd" (prompt_pwd) "$__fish_prompt_normal" (fish_vi_prompt_cm) '# '
+
+		case '*'
+
+		if not set -q __fish_prompt_cwd
+			set -g __fish_prompt_cwd (set_color $fish_color_cwd)
+		end
+
+		echo -n -s "$USER" @ "$__fish_prompt_hostname" ' ' "$__fish_prompt_cwd" (prompt_pwd) "$__fish_prompt_normal" (fish_vi_prompt_cm) '> '
+
+	end
+end