From e7e8e243a2e7955a95c92c18367158a69e6d7800 Mon Sep 17 00:00:00 2001
From: Jeremy Ashkenas <jashkenas@gmail.com>
Date: Fri, 25 Dec 2009 00:02:27 -0800
Subject: [PATCH] better error warnings on the command line

---
 lib/coffee_script/command_line.rb | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/coffee_script/command_line.rb b/lib/coffee_script/command_line.rb
index f7bf6c94..33439f85 100644
--- a/lib/coffee_script/command_line.rb
+++ b/lib/coffee_script/command_line.rb
@@ -105,12 +105,18 @@ Usage:
     # Use Narwhal to run an interactive CoffeeScript session.
     def launch_repl
       exec "narwhal lib/coffee_script/narwhal/js/launcher.js"
+    rescue Errno::ENOENT
+      puts "Error: Narwhal must be installed to use the interactive REPL."
+      exit(1)
     end
 
     # Use Narwhal to compile and execute CoffeeScripts.
     def run_scripts
       sources = @sources.join(' ')
       exec "narwhal lib/coffee_script/narwhal/js/launcher.js #{sources}"
+    rescue Errno::ENOENT
+      puts "Error: Narwhal must be installed in order to execute CoffeeScripts."
+      exit(1)
     end
 
     # Print the tokens that the lexer generates from a source script.