guard explained

1 files changed, 6 insertions, 0 deletions

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