COP 4020 Oz Programming Language Presentation Chris Savela Zak Roessler.
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Transcript of COP 4020 Oz Programming Language Presentation Chris Savela Zak Roessler.
COP 4020Oz Programming Language
Presentation
Chris Savela
Zak Roessler
COP 4020: Oz Programming Language page 2
Oz: Table of Contents
History of Oz Origins of Oz Foundations of Oz Versions of Oz Applications of Oz Oz Language and Basics Programming Conclusion
COP 4020: Oz Programming Language page 3
Oz: History
History of Oz Oz was conceived in 1991 by Gert Smolka at Saarland University in
Sweden
Development continued in collaboration with Seif Haridi and Peter van Roy at Swedish Institute of Computer Science
Since 1999, Oz has been continually developed by an international group, the Mozart Consortium, which originally consisted of Saarland University, the Swedish Institute of Computer Science, and the Université catholique de Louvain
COP 4020: Oz Programming Language page 4
Oz: History
History of Oz In 2005, the responsibility for managing Mozart development was
transferred to a core group, the Mozart Board, with the express purpose of opening Mozart development to a larger community.
The Mozart Programming System is the primary implementation of Oz. It is released with an open source license by the Mozart Consortium. Mozart has been ported to different flavors of Unix, FreeBSD, Linux, Microsoft Windows, and Mac OS X.
COP 4020: Oz Programming Language page 5
Oz: Origins of Oz
Oz is an experimental language and draws from experience in programming languages such as: Prolog - general purpose logic programming language associated
with artificial intelligence and computational linguistics
Erland - is a general-purpose concurrent programming language
Lisp/Scheme - is a functional programming language and one of the two main dialects of the programming language Lisp
COP 4020: Oz Programming Language page 6
Oz: Foundations
Foundations of Oz Oz combines the most important features of object-oriented
programming, by providing state, abstract data types, classes, objects, and inheritance
Oz provides the most important features of logic programming and constraint programming by providing logic variables, disjunctive constructs, and programmable search strategies.
COP 4020: Oz Programming Language page 7
Oz: Foundations
Foundations of Oz Oz provides the most important features of functional programming
by providing composition syntax, first-class procedures, and lexical scoping. Every entity in Oz is first class including procedures, threads, classes, methods, and objects.
A programming language is said to have first-class functions if it treats functions as first-class citizens. Specifically, this means that the language supports passing functions as arguments to other functions, returning them as the values from other functions, and assigning them to variables or storing them in data structures.
COP 4020: Oz Programming Language page 8
Oz: Foundations
Foundations of Oz Oz is a concurrent language where users can create dynamically
any number of sequential threads that can interact with each other. Each thread in Oz is a dataflow thread
Executing a statement in Oz proceeds only when all real dataflow dependencies on the variables involved are resolved.
COP 4020: Oz Programming Language page 9
Oz: Foundations
Foundations of Oz Using the Mozart development environment for Oz one can create
a distributed environment for Oz computations.
Multiple Oz sites can connect together and automatically behave like a single Oz computation sharing variables, objects and classes and procedures.
Sites disconnect automatically when references between entities on different sites cease to exist.
In a distributed environment Oz provides language security.
COP 4020: Oz Programming Language page 10
Oz: Versions of Oz
Oz 1 Supported a fine-grained notion of concurrency where each
statement could potentially be executed concurrently.
Fine-grained model similar to actor model
This model was theoretically appealing, but it had drawbacks: Very hard for the programmer to control resources of the application
Very hard to debug
Object model was unnecessarily awkward
COP 4020: Oz Programming Language page 11
Oz: Versions of Oz
Oz 2 Introduced a thread based concurrency model with explicit creation
of threads to remedy issues with concurrency from Oz 1.
A powerful new object system was introduced that included traditional exception handling.
Also constraint solving and search capabilities were enhanced
COP 4020: Oz Programming Language page 12
Oz: Versions of Oz
Oz 3 – Current version Conservatively extends Oz 2 two new concepts:
Functors Software components that specify a module in terms of other module needs Supports incremental construction of program components that may be
addressed over the internet by URL’s
Futures Logic variable that can be read but not written Allows safe dataflow synchronization over the internet
COP 4020: Oz Programming Language page 13
Oz: Applications
Applications of Oz Teaching language
Developed as a way to teach programming by gradually introducing new concepts and showing what they are good for.
To show how all major programming paradigms fit in a uniform framework.
Simulations The imitation of the operation of a real-world process or system over time
COP 4020: Oz Programming Language page 14
Oz: Applications
Applications of Oz Multi-Agent Systems
System composed of multiple interacting intelligent agents within an environment. Multi-agent systems can be used to solve problems that are difficult or impossible
for an individual agent or a monolithic system to solve
Natural Language Processing The process of a computer extracting meaningful information from natural
language input and/or producing natural language output.
Virtual Reality Applies to computer-simulated environments that can simulate physical presence
in places in the real world, as well as in imaginary worlds
COP 4020: Oz Programming Language page 15
Oz: Language Basics
Language Basics Oz language referred to as syntactic sugar
Syntactic Sugar refers to syntax within a programming language that is designed to make things easier to read or to express.
It makes the language "sweeter" for humans to use: things can be expressed more clearly, more concisely, or in an alternative style that some may prefer
COP 4020: Oz Programming Language page 16
Oz: Language Basics
Language Basics Oz is referred to as a small kernel language
Oz execution model Consist of dataflow threads observing a shared store.
Threads contain statement sequences and communicate through a shared references in the store.
A thread is dataflow if it only executes its next statement when all the values the statement needs are available.
If a statement needs a value that is not available yet, the thread will block until it can access that value.
COP 4020: Oz Programming Language page 17
Oz: Language Basics
Oz Data Availability Implemented using logical variables
The shared store is not physical memory
The shared store is an abstract store which only allows operations that are legal for the entities involved
There is no direct way to inspect the internal representations of entities
COP 4020: Oz Programming Language page 18
Oz: Language Basics
OZ data store can contain Bound and unbound logic variables
Cells which are mutable pointers which points to variables
Procedures
Variables can reference the names of procedures and cells
Variables can be bound to any entity, including other variables
Variable and produced stores are monotonic, i.e., information can only be added to them, not changed or removed.
COP 4020: Oz Programming Language page 19
Oz: Base Environment
A mapping of identifiers to values Organized in modules Available via field selection.
COP 4020: Oz Programming Language page 20
Oz: Base Environment
COP 4020: Oz Programming Language page 21
Oz: Base Environment
Module Value
Contains procedures that con operate on many types {Value. ‘=‘ X Y}
Unifies {Value ‘==‘ X Y ? B }
Equality {Value. ‘\\=‘ X Y ? B }
Not Equal
COP 4020: Oz Programming Language page 22
Oz: Base Environment
Module Numbers
Contains procedures operating on numbers {Number.is +X ? B }
IsNumber {Number. ‘+’ +FI1 +FI2 ? FI3 }
Sum {Number.pow +FI1 +FI2 ? FI3 }
FI1 to power of FI2
COP 4020: Oz Programming Language page 23
Oz: Base Environment
Module Floats
Contains procedures operating on floats {Float.is +X ? B }
IsFloat {Float. ‘/’ +FI +F2 ? F3 }
F1 divided by F2 {Float.sqrt + F1 ? F2 }
Square Root
COP 4020: Oz Programming Language page 24
Oz: Base Environment
Module Functor
Support for module specification Expression that specifies components of a module
COP 4020: Oz Programming Language page 25
Oz: Base Environment
Type Oz is dynamically typed
A variables type and value are unknown until it is bound to an Oz value. Shares a common structure
Float < Number < Value
Array < Chunk < Value
COP 4020: Oz Programming Language page 26
Oz: Programming
Basics Computations performed by a sequential process, executing one
statement after another. Process is a thread
COP 4020: Oz Programming Language page 27
Oz: Programming
Basics Simple programs
local X Y Z in s end Execute s in the scope of X Y Z
Another
local I F in
I = 5
F = 5.5
{Browse [ I F C] }
end
COP 4020: Oz Programming Language page 28
Oz: Programming
Basics - control If Statement
if B then S1 else S2 Procedure
Can be defined, passed as argument or stored in a record Unique
proc {P X1 … Xn} S end
COP 4020: Oz Programming Language page 29
Oz: Programming
Creating a program that copies files First things first
Download and intall Oz environment Compile with ozc.exe Run with ozengine.exe
COP 4020: Oz Programming Language page 30
Oz: Programming functor
<Module import><Functor Body>
end
COP 4020: Oz Programming Language page 31
Oz: Programming functor
import Application Open<Functor Body>
end
COP 4020: Oz Programming Language page 32
Oz: Programming functor
import Application Opendefine
<Argument process>Status = try
<Opening input and output files>in <Copying input to output file>catch _ then 1end
<Terminating the application>end
COP 4020: Oz Programming Language page 33
Oz: Programming functor
import Application Opendefine
Args = {Application.getargs record(‘in’ (single type:string)‘out’ (single type:string))}
Status = try <Opening input and output files>in <Copying input to output file>catch _ then 1end
<Terminating the application>end
COP 4020: Oz Programming Language page 34
Oz: Programming functor
import Application Opendefine
Args = {Application.getargs record(‘in’ (single type:string)‘out’ (single type:string))}
Status = try I = {new Open.file init(source: Args.’in’)} O= {new Open file init(name Args. ‘out’
flags:[write create truncate])}in <Copying input to output file>catch _ then 1end
<Terminating the application>end
COP 4020: Oz Programming Language page 35
Oz: Programming functor
import Application Opendefine
Args = {Application.getargs record(‘in’ (single type:string)‘out’ (single type:string))}
Status = try I = {new Open.file init(source: Args.’in’)} O= {new Open file init(name Args. ‘out’
flags:[write create truncate])}in local proc {copy} S={I read(list::$} in if S\=“” then
{O write(vs:S)} {copy} end
end in {copy} endcatch _ then 1end
<Terminating the application>end
COP 4020: Oz Programming Language page 36
Oz: Programming functor
import Application Opendefine
Args = {Application.getargs record(‘in’ (single type:string)‘out’ (single type:string))}
Status = try I = {new Open.file init(source: Args.’in’)} O= {new Open file init(name Args. ‘out’
flags:[write create truncate])}in local proc {copy} S={I read(list::$} in if S\=“” then
{O write(vs:S)} {copy} end
end in {copy} endcatch _ then 1end
{Application.exit Status}end
COP 4020: Oz Programming Language page 37
Oz: Programming
File A File B
COP 4020: Oz Programming Language page 38
Oz: Conclusions
How do programming languages get their power? Traditional languages use libraries to proivde extra functionality.
The library approach soon hits a brick wall by the limits of its underlying language.
Oz has been designed such that has a small number of concepts can be combined in many ways. The designers of Oz believe the concept approach can go much further and have used this in their design.
Oz provides a large set of basic concepts and allows the developers to choose the paradigm needed to solve the problem.
COP 4020: Oz Programming Language page 39
Oz: Conclusions
Flexibility comes with a price. The execution of OZ is very slow compared to other languages. On a set of benchmarks it about 50 times slower then that of gcc compiler for C.
COP 4020: Oz Programming Language page 40
Resources
http://en.wikipedia.org/wiki/Oz_(programming_language) http://en.wikipedia.org/wiki/Prolog http://en.wikipedia.org/wiki/Erlang_(programming_language) http://en.wikipedia.org/wiki/Scheme_programming_language http://www.mozart-oz.org/documentation/tutorial/ http://www.mozart-oz.org/documentation/tutorial/node1.html#label2 http://www.mozart-oz.org/papers/abstracts/volume1000.html
COP 4020Oz Programming Language
Presentation
Chris Savela
Zak Roessler