diff --git a/tst/ranges.rb b/tst/ranges.rb
new file mode 100644
index 0000000..82894c3
--- /dev/null
+++ b/tst/ranges.rb
@@ -0,0 +1,52 @@
+
+#
+# exploring ranges...
+
+# 0-59
+# 10~30
+
+class R
+  include Comparable
+
+  MAX = 59
+  attr_reader :current, :type, :slash
+
+  def initialize(current, type, slash)
+    @current = current
+    @type = type
+    @slash = slash
+  end
+
+  def to_i
+    @current
+  end
+
+  def <=>(b)
+    current <=> b.to_i
+  end
+  def succ
+    c = current
+    loop do
+      c = c.succ
+      return R.new(c, type, slash) if (c % slash) == 0
+      fail 'overflow' if c > MAX
+    end
+  end
+end
+
+p (R.new(0, :hyphen, 1)..R.new(59, :hyphen, 1)).to_a.size
+
+range = R.new(0, :hyphen, 2)..R.new(59, :hyphen, 2)
+p range.to_a.size
+
+p range.include?(0)
+p range.include?(1)
+p range.include?(2)
+p range.include?(100)
+
+p range.cover?(R.new(10, :hyphen, 2)..R.new(20, :hyphen, 2))
+p range.cover?(R.new(10, :hyphen, 2)..R.new(70, :hyphen, 2))
+p range.cover?(R.new(10, :hyphen, 1)..R.new(20, :hyphen, 1))
+
+p range.to_a.collect(&:to_i)
+