Shorten dir path, if POWERLEVEL9K_SHORTEN_PWD_LENGTH is set.

powerlevel9k.zsh-theme

@@ -318,7 +318,13 @@ prompt_context() {
 
 # Dir: current working directory
 prompt_dir() {
-  $1_prompt_segment $0 blue $DEFAULT_COLOR '%~'
+  local current_path='%~'
+  if [[ -n "$POWERLEVEL9K_SHORTEN_PWD_LENGTH" ]]; then
+    # shorten path to $POWERLEVEL9K_SHORTEN_PWD_LENGTH characters
+    local current_path="%${POWERLEVEL9K_SHORTEN_PWD_LENGTH}<..<%~%<<"
+  fi
+
+  $1_prompt_segment $0 blue $DEFAULT_COLOR $current_path
 }
 
 # Command number (in local history)