Changed lume.reduce() to support non-array tables, updated tests

lume.lua

@@ -259,9 +259,18 @@ end
 
 
 function lume.reduce(t, fn, first)
-  local acc = first or t[1]
-  assert(acc, "reduce of an empty array with no first value")
-  for i = first and 1 or 2, #t do acc = fn(acc, t[i]) end
+  local acc = first
+  local started = first and true or false
+  local iter = getiter(t)
+  for k, v in iter(t) do
+    if started then
+      acc = fn(acc, v)
+    else
+      acc = v
+      started = true
+    end
+  end
+  assert(started, "reduce of an empty table with no first value")
   return acc
 end
 

test/test_lume.lua

@@ -230,6 +230,9 @@ tests["lume.reduce"] = function()
   testeq( lume.reduce({1, 2, 3, 4}, add, 5),          15          )
   testeq( lume.reduce({1}, add),                      1           )
   testeq( lume.reduce({}, concat, "potato"),          "potato"    )
+  testeq( lume.reduce({a=1, b=2}, add, 5),            8           )
+  testeq( lume.reduce({a=1, b=2}, add),               3           )
+  tester.test.error(lume.reduce, {}, add)
 end
 
 -- lume.set