Adding --help mode and update in README to same change

For the program to more easily take arguments as well as make using the program much more simple, the way to use the program is changed. You now feed the program the directory containing the files to rename instead of every single file that you would like renamed.

Author: truesilver92

README.md

@@ -5,4 +5,8 @@ What it does:
      Provides a simple way to rename similarly named files at the same time
 
 How to use:
-    ./batch_rename.scm [function taking arguments 'totalnumberoffiles' 'filename to change'] [files separated by spaces]
+
+batch_rename [options]
+  -h, --help Display this help
+  -f, --function [lambda expression] A Lambda expression accepting totalfilecount and current file as arguments and returning the altered filename
+  -d, --directory [Directory] The directory containing the files that function will act on

batch_rename.scm

@@ -1,7 +1,31 @@
 #!/usr/local/bin/guile \
 -e main -s
 !#
+(use-modules (ice-9 getopt-long))
+
+(define help_display "\
+
+batch_rename [options]
+  -h, --help Display this help
+  -f, --function [lambda expression] A Lambda expression accepting totalfilecount and current file as arguments and returning the altered filename
+  -d, --directory [Directory] The directory containing the files that function will act on
+
+")
+
 (define (main args)
-  (write args)
+  (define option-spec
+    '((function (single-char #\f) (value optional))
+      (directory (single-char #\d) (value optional))
+      (help (single-char #\h) (value #f))))
+  (define options (getopt-long args option-spec))
+  (define function-code (option-ref options 'function #f))
+  (define directory-name (option-ref options 'directory #f))
+  (define help-wanted (option-ref options 'help #f))
+  (if help-wanted
+      (display help_display))
+  (write "function-code: ")
+  (write function-code)
+  (newline)
+  (write "directory-name: ")
+  (write directory-name)
   (newline))
-