Function object
In Ruby, several objects can be considered function objects, in particular Method and Proc objects. Ruby also has two kinds of objects that can be thought of as semi-function objects: UnboundMethod and block. UnboundMethods must first be bound to an object (thus becoming a Method) before they can be used as a function object. Blocks can be called like function objects, but to be used in any other capacity as an object (e.g. passed as an argument) they must first be converted to a Proc. More recently, symbols (accessed via the literal unary indicator codice_35) can also be converted to codice_36s. Using Ruby's unary codice_37 operator—equivalent to calling codice_38 on an object, and assuming that method exists—the Ruby Extensions Project created a simple hack.
RubyCocoa
RubyCocoa is a Mac OS X framework that provides a bridge between the Ruby and the Objective-C programming languages, allowing the user to manipulate Objective-C objects from Ruby, and vice versa. It makes it possible to write a Cocoa application completely in Ruby as well as to write an application that mixes Ruby and Objective-C code. An Apple project called MacRuby was under development to replace RubyCocoa in 2008. A proprietary spin-off called RubyMotion was subsequently released in 2012, available for iOS, OS X and Android.