Changed lume.merge() functionality, updated README and doc

- The old functionality of lume.merge() is now spread across
  lume.merge() (for tables) and lume.concat() (for arrays). Both these
  functions create new tables rather than operating in-place
- Changed lume.fn() to use lume.concat() internally

README.md

@@ -151,12 +151,11 @@ an array and retains its original keys.
 lume.filter({1, 2, 3, 4}, function(x) return x % 2 == 0 end) -- Returns {2, 4}
 ```
 
-### lume.merge(t, t2 [, retainkeys])
-Merges all the values from the table `t2` into `t` in place. If `retainkeys` is
-true the table is not treated as an array and retains its original keys; if `t`
-and `t2` have a conflicting key, the value from `t2` is used.
+### lume.merge(...)
+Returns a new table with all the given tables merged together. If a key exists
+in multiple tables the right-most table's value is used.
 ```lua
-lume.merge({2, 3}, {4, 5}) -- Returns {2, 3, 4, 5}
+lume.merge({a=1, b=2, c=3}, {c=8, d=9}) -- Returns {a=1, b=2, c=8, d=9}
 ```
 
 ### lume.concat(...)

lume.lua

@@ -252,11 +252,16 @@ function lume.filter(t, fn, retainkeys)
 end
 
 
-function lume.merge(t, t2, retainkeys)
-  for k, v in pairs(t2) do
-    t[retainkeys and k or (#t + 1)] = v
+function lume.merge(...)
+  local rtn = {}
+  for i = 1, select("#", ...) do
+    local t = select(i, ...)
+    local iter = getiter(t)
+    for k, v in iter(t) do
+      rtn[k] = v
     end
-  return t
+  end
+  return rtn
 end
 
 
@@ -359,7 +364,7 @@ function lume.fn(fn, ...)
   assert(iscallable(fn), "expected a function as the first argument")
   local args = { ... }
   return function(...)
-    local a = lume.merge(lume.clone(args), {...})
+    local a = lume.concat(args, { ... })
     return fn(unpack(a))
   end
 end

test/test_lume.lua

@@ -216,8 +216,9 @@ end
 
 -- lume.merge
 tests["lume.merge"] = function()
-  testeq( lume.merge({1, 2, 3}, {8, 9, 0}),         {1, 2, 3, 8, 9, 0}  )
-  testeq( lume.merge({a=1, b=2}, {b=3, c=4}, true), {a=1, b=3, c=4}     )
+  testeq( lume.merge(),                       {}              )
+  testeq( lume.merge({x=1, y=2}),             {x=1, y=2}      )
+  testeq( lume.merge({a=1, b=2}, {b=3, c=4}), {a=1, b=3, c=4} )
 end
 
 -- lume.concat