Future Programming Languages

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Future Programming Languages

• Ben Logsdon, Dustin Beadle,
• Jaim Ahmed, Nivedita Kaluskar, Hongchao Li

CS Department, University of Georgia April. 13th
2005
2
Outline

• Python 3000
• Ruby 2
• Groovy
• Scala

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Python 3000

• Mystery Science meets Windows

4
From the creator

• one day you may find that you are _already_
  using Python 3000 -- only it won't be called
  that, but rather something like Python 2.8.7.

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About Python Development

• Open Source www.python.org/dev
• Python Enhancement Proposals
• www.python.org/peps
• BDFL Guido van Rossum guides development
• PEPs are used in further versions of Python such
  as multi-line imports (328) and reverse
  iteration(322)

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Sample PEPs

• http//www.python.org/peps/pep-0328.html
• Fix import statements
• Current
• from Tkinter import Tk, Frame, Button\ Entry,
  Canvas, Text, LEFT, DISABLED\ NORMAL, RIDGE, END
• To from Tkinter import (Tk,Frame,Button,Entry
  , Canvas, Text, LEFT,DISABLED,NORMAL,RIDGE,END)
• Change to absolute imports indicating relative
  paths through dots
• ex) from foo import bar gt from .foo import bar

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Python 2.5

• Add support for shadow passwords
• Deprecate and/or remove old modules such as
  gopher and posixfile
• Remove support for old platforms
• AST-based compiler (Abstract Syntax Tree)
• Decimal data type with specified precision (327)

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• Ruby 2

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Intro To Ruby

• Designed to be a successor to Perl.
• Dynamically Typed, OO, Scripting Language
• Contains a garbage collector, contains threads,
  fully integrated closures and iterators, plus
  proper meta-classes.
• Open source, multi-platform can be download at...
• http//www.ruby-lang.org/en/20020102.html

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Ruby vs Python

• Both are High Level languages
• In Ruby, everything is an Object. Python allows
  programming with out objects if needed.
• Python has a much larger range of libraries for
  use. However, Ruby can make use of these through
  Ruby/Python, although performance can suffer.
• According to The Great Computer Language Shootout
  Python has better performance time.
• More info at Python Vs Ruby

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Ruby on Rails

• Flagship Ruby Program
• Framework for developing web applications at a
  quick but sustainable pace
• Automatic Object-Relational-Mapping class
• Templated and non-templated page generation
• Automatic generation of unit tests
• Powerful and intelligent multi-level caching
• Pre-database entry validation
• Go to http//www.rubyonrails.org/ to check out an
  example of what Ruby can do.

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Future of Ruby.. Ruby 2

• Ruby 2, or Ruby Rite, is still aways away from
  being released.
• It is promised to be a bytecode based,
  thread-safe virtual machine.
• Changes include,
• variable scopes
• the difference between statement and expressions
• semantics of multiple values
• private method visibility
• range in condition
• keyword arguments
• new hash literals

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Future of Ruby.. Ruby 2

• Ruby 2 is still quite a ways away, the current
  version of ruby is still 1.8
• Most syntax changes will be complete by version
  1.9 however.
• More details about Ruby Rite can be found here.

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• Groovy

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Groovy

• An object oriented programming language designed
  for the Java platform.
• Makes available the features in Ruby, Smalltalk,
  Python using a Java-like syntax.
• Can be used as a replacement for Java for small
  and medium sized applications.
• Makes writing test cases for unit tests very
  easy.

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Features

• Uses Java syntax, but with far fewer rules.
• Does not require semi colons access modifiers
  and variable types are optional.
• Makes use of standard Java libraries including
  Collection and File I/O.
• Can utilize any Java library from within Groovy,
  including JUnit.
• Includes support for Closures, SQL, Servlets,
  Beans, Unit testing etc.

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Closures in Groovy

• A closure is one or more program statements
  enclosed in curly brackets.
• closureArguments-gt statements
• The main difference between a closure and method
  is that closures do not require a class or a
  method name.
• Closures can be assigned to a variable when
  created which can be passed around the program
  like any other variable.

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Closures (Contd)

• Example Method definition
• package example.math
• public class MyMath
• public static long square(int numberToSquare)
  
• return numberToSquare numberToSquare
• Corresponding Closure definition
• def c numberToSquare -gt numberToSquare
  numberToSquare

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Closures Vs Code Blocks

• Code within a code block is executed by the
  virtual machine as soon as it is encountered.
• Statements within closures are not executed until
  the call() is made on the closure.
• Eg y c.call(x) instead of
• y example.math.MyMath.square(x) for
  the method block.

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Unit testing with Groovy

• Groovy's relaxed Java-like syntax, its reuse of
  standard Java libraries, and its rapid
  build-and-run cycle make it an ideal candidate
  for rapidly developing unit tests.
• Groovy extends JUnit and this allows running of
  tests via the groovy command.
• GroovyTestCase gives some particularly handy
  assert methods.
• Eg assertArrayEquals, asserts that two arrays
  are equal by checking their individual values and
  respective lengths.

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Contd

• To write unit tests in groovy, a class extending
• groovy.util.GroovyTestCase has to be created.
• Example
• import groovy.util.GroovyTestCase
• class MyTest extends GroovyTestCase
• void testSomething()
• assert 1 1

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• Scala

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• Scala is object-oriented
• Scala is a pure object-oriented language in the
  sense that every value is an object.
• Types and behavior of objects are described by
  classes and traits.
• Class abstractions are extended by subclassing
  and a flexible mixin-based composition mechanism
  as a clean replacement for multiple inheritance.
• example

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• Scala is functional
• Scala is also a functional language in the sense
  that every function is a value.
• Example
• class MyBool(x Boolean) def and(that
  MyBool) MyBool if (x) that else this
• def or(that MyBool) MyBool if (x) this
  else that def negate MyBool new
  MyBool(!x)

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• Scala is statically typed
• Scala is equipped with an expressive type system
  that enforces statically that abstractions are
  used in a safe and coherent manner.
• In particular, the type system supports
• generic classes,
• variance annotations,
• upper and lower type bounds,
• classes and abstract types as object members,
• compound types,
• explicitly typed self references,
• views, and
• polymorphic methods.

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• Polymorphic Method Example
• object PolyTest with Application
• def dupT(x T, n Int) ListT if
  (n 0) Nil else x dup(x, n - 1)
• Console.println(dupInt(3, 4))
  Console.println(dup("three", 3))

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• Scala is extensible
• Scala provides a unique combination of language
  mechanisms that make it easy to smoothly add new
  language constructs in form of libraries.

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• Scala interoperates with Java and .NET
• Scala is designed to interoperate well with
  popular programming environments like the Java 2
  Runtime Environment (JRE) and the .NET CLR.
• In particular, the interaction with mainstream
  object-oriented languages like Java and C is as
  smooth as possible.

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Reference

• http//www.python.org
• http//www.rubygarden.org
• http//groovy.codehaus.org
• http//scala.epfl.ch