2016 Update

Task/Catamorphism/Lua/catamorphism.lua

@@ -0,0 +1,29 @@
+table.unpack = table.unpack or unpack -- 5.1 compatibility
+local nums = {1,2,3,4,5,6,7,8,9}
+
+function add(a,b)
+   return a+b
+end
+
+function mult(a,b)
+   return a*b
+end
+
+function cat(a,b)
+   return tostring(a)..tostring(b)
+end
+
+local function reduce(fun,a,b,...)
+   if ... then
+      return reduce(fun,fun(a,b),...)
+   else
+      return fun(a,b)
+   end
+end
+
+local arithmetic_sum = function (...) return reduce(add,...) end
+local factorial5 = reduce(mult,5,4,3,2,1)
+
+print("Σ(1..9)   : ",arithmetic_sum(table.unpack(nums)))
+print("5!        : ",factorial5)
+print("cat {1..9}: ",reduce(cat,table.unpack(nums)))