From 9c9fe95a3580307215d76f130102729c5bb521c9 Mon Sep 17 00:00:00 2001
From: Javran Cheng <Javran.c@gmail.com>
Date: Fri, 25 Sep 2015 07:28:53 -0400
Subject: guard explained

---
 src/Hakyll/Init.hs | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'src')

diff --git a/src/Hakyll/Init.hs b/src/Hakyll/Init.hs
index 816ef43..71055f0 100644
--- a/src/Hakyll/Init.hs
+++ b/src/Hakyll/Init.hs
@@ -31,6 +31,12 @@ main = do
     files    <- getRecursiveContents (const $ return False) srcDir
 
     case args of
+        -- When the argument begins with hyphens, it's more likely that the user
+        -- intends to attempt some arguments like ("--help", "-h", "--version", etc.)
+        -- rather than create directory with that name.
+        -- If dstDir begins with hyphens, the guard will prevent it from creating
+        -- directory with that name so we can fall to the second alternative
+        -- which prints a usage info for user.
         [dstDir] | not ("-" `isPrefixOf` dstDir) -> do
             forM_ files $ \file -> do
                 let dst = dstDir </> file
-- 
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