diff --git a/sys/apis/map.lua b/sys/apis/map.lua
index 4fc3bc8..9e4ab93 100644
--- a/sys/apis/map.lua
+++ b/sys/apis/map.lua
@@ -3,6 +3,10 @@ local Util = require('util')
 
 local Map = { }
 
+-- TODO: refactor
+Map.merge = Util.merge
+Map.shallowCopy = Util.shallowCopy
+
 function Map.removeMatches(t, values)
 	local function matchAll(entry)
 		for k, v in pairs(values) do
@@ -25,7 +29,7 @@ function Map.prune(t, fn)
 	for _,k in pairs(Util.keys(t)) do
 		local v = t[k]
 		if type(v) == 'table' then
-			t[k] = Util.prune(v, fn)
+			t[k] = Map.prune(v, fn)
 		end
 		if not fn(t[k]) then
 			t[k] = nil
@@ -34,4 +38,12 @@ function Map.prune(t, fn)
 	return t
 end
 
+function Map.size(list)
+	local length = 0
+	for _ in pairs(list) do
+		length = length + 1
+	end
+	return length
+end
+
 return Map
diff --git a/sys/apis/util.lua b/sys/apis/util.lua
index 8b3d26b..16d00b4 100644
--- a/sys/apis/util.lua
+++ b/sys/apis/util.lua
@@ -277,8 +277,9 @@ function Util.filter(it, f)
 end
 
 function Util.reduce(t, fn, acc)
+	acc = acc or 0
 	for _, v in pairs(t) do
-		fn(acc, v)
+		acc = fn(acc, v)
 	end
 	return acc
 end