Merge pull request #6 from cassiozen/master

Bind partial arguments

README.md

@@ -616,15 +616,20 @@ end)
 
 ## bind
 
-`_.bind(function, table)`
+`_.bind(function, table, [arguments])`
 
-Bind a function to a table, meaning that whenever the function is called, the value of self will be the table. 
+Bind a function to a table, meaning that whenever the function is called, the value of self will be the table. Optionally, bind arguments to the function to pre-fill them, also known as partial application.
 
 ```lua
-local func = function(self, greeting) return greeting .. ': ' .. self.name end
-func = _.bind(func, {name = 'moe'})
+local greet = function(self, greeting) return greeting .. ': ' .. self.name end
+
+func = _.bind(greet, {name = 'moe'})
 func('hi')
 => 'hi: moe'
+
+func = _.bind(greet, {name = 'moe'}, 'hey')
+func()
+=> 'hey: moe'
 ```
 
 

lib/underscore.lua

@@ -418,9 +418,10 @@ function _.after(times, func)
   end
 end
 
-function _.bind(func, object)
+function _.bind(func, context, ...)
+  local arguments = unpack({...})
   return function(...)
-    return func(object, ...)
+    return func(context, unpack(_.concat(arguments,arg)))
   end
 end
 

spec/functions_spec.lua

@@ -58,9 +58,14 @@ end)
 
 describe("#bind", function()
   local table = {name = "moe"}
-  local greet = function(self) return "hi: " .. self.name end
+  local greet = function(self, greeting) return greeting .. ": " .. self.name end
   it("returns a closure that binds a function to a table scope ", function()
     local binded = _.bind(greet, table)
+    assert.equals(binded("hi"), "hi: moe")
+  end)
+
+  it("creates a partial application by pre-filling arguments", function()
+    local binded = _.bind(greet, table, "hi")
     assert.equals(binded(), "hi: moe")
   end)
 end)