Just another update

Task/Standard-deviation/Lua/standard-deviation.lua

@@ -0,0 +1,12 @@
+function stdev()
+  local sum, sumsq, k = 0,0,0
+  return function(n)
+    sum, sumsq, k = sum + n, sumsq + n^2, k+1
+    return math.sqrt((sumsq / k) - (sum/k)^2)
+  end
+end
+
+ldev = stdev()
+for i, v in ipairs{2,4,4,4,5,5,7,9} do
+  print(ldev(v))
+end