Update ZSH prompt

Include a shortened version of the current directory.

oni/home/data/config.scm

@@ -54,7 +54,8 @@
              (environment-variables
               '(("HISTFILE" . "$HOME/.zsh/histfile")
                 ("HISTSIZE" . "1000")
-                ("SAVEHIST" . "1000")))
+                ("SAVEHIST" . "1000")
+                ("PROMPT" . "%T \\$(spwd) %B%(?.%F{2}.%F{1}[%?])>%b%f ")))
              (zshrc
               (list
                (mixed-text-file

zsh/.zsh/functions/spwd

@@ -0,0 +1,25 @@
+# From https://stackoverflow.com/a/45336078
+paths=(${(s:/:)PWD})
+
+cur_path='/'
+cur_short_path='/'
+for directory in ${paths[@]}
+do
+    cur_dir=''
+    for (( i=0; i<${#directory}; i++ )); do
+        cur_dir+="${directory:$i:1}"
+        matching=("$cur_path"/"$cur_dir"*/)
+        if [[ ${#matching[@]} -eq 1 ]]; then
+            break
+        fi
+    done
+    cur_short_path+="$cur_dir/"
+    cur_path+="$directory/"
+
+    if [[ $cur_path == $HOME/ ]];
+    then cur_short_path='~/'
+    fi
+done
+
+printf %b "${cur_short_path: : -1}"
+echo

zsh/zshrc.org

@@ -207,6 +207,6 @@ Autoload any ZSH function from =$HOME/.zsh/functions=.
   Set the actual prompts.
 
   #+begin_src sh
-    PROMPT='%T %2~ %B%(?.%F{2}.%F{1})→%b '
+    PROMPT='%T $(spwd) %B%(?.%F{2}.%F{1}[%?])>%b%f '
     RPROMPT='${vcs_info_msg_0_}'
   #+end_src