add exercises

1 files changed, 21 insertions, 0 deletions

diff --git a/exercism/emacs-lisp/binary/binary.el b/exercism/emacs-lisp/binary/binary.el
new file mode 100644
index 0000000..2a2fba3
--- /dev/null
+++ b/exercism/emacs-lisp/binary/binary.el
@@ -0,0 +1,21 @@
+;;; binary.el --- Binary exercise (exercism)
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'cl)
+
+(defun to-decimal-helper (str)
+  (cl-loop with result = 0
+           for c across str
+           do (setq result (+ (- c ?0) (* 2 result)))
+           finally return result))
+
+(defun to-decimal (str)
+  (if (string-match "[01]+" str)
+      (to-decimal-helper str)
+    0))
+
+(provide 'binary)
+;;; binary.el ends here