Introduction to Gura Programming Language

Introduction to Gura Programming Language

www.gura-lang.org

Copyright © 2014 [email protected]

LL Diver on Aug 23, 2014

Copyright (C) 2014 ypsitau 2/49

Author

Name Yutaka Saito

Experience Embedded Firmware to GUI

Job History Electric-app maker, chip maker, venture

Current Job Free, unemployed rather

Favorite Lang C++, Gura

devoted to Gura


Extension Module

Iterator Operation

Basic Specification

What's Gura?

Agenda

What's Gura?


What's Gura?

Repeat processes appear in programs so often.

for (i = 0; i < 10; i++) {}

people.each do |person|end

for x in range(10):hoge

Can I deal them without verbose control sequence?


Case Study (1)

Here's a number sequence: -3, -2, -1, 0, 1, 2, 3.Make a list of squared values of them.

Think it with yourfavorite language ...

x

y


Gura's Program (1)

x = [-3, -2, -1, 0, 1, 2, 3]y = x * x


Gura's Program (1)

x = [-3, -2, -1, 0, 1, 2, 3]y = x * x

Multiplying iterator is generated.

Its evaluation creates list.

Iterator Lists generate iterators.1

2

3Evaluation

List List

Iterator

Iterator

List


Case Study (2)

Create a program that reads a text file and printsits content along with line numbers.

Think it with yourfavorite language …

1: #include <std2: int main()3: {4: printf(“H5: }


Gura's Program (2)

printf('%d: %s',1.., readlines('hello.c'))


Gura's Program (2)

printf('%d: %s',1.., readlines('hello.c'))

Iterator that executes printffor each item is generated.

It's destroyed after evaluated.

1

2

Iterator Iterator

Iterator

Evaluation


After All, Gura is ..

A language that can generate iteratorsfrom iterators and evaluate them.

Gura calls this operation “Mapping”.

Iterator

IteratorIterator

Iterator

Iterator Iterator

Iterator Evaluation


Expected Benefits

Simplifies codes of repeat process.

Facilitates parallel computing, maybe.

1

2


Idea for Parallel Computing

Elements in iterator generated last

Iterator generationrequires less load.

Evaluation stageneeds much load.

Distributes elements to processorsfor evaluation. Eval

Iterator

IteratorIterator

Iterator

Iterator Iterator

Iterator Evaluation

Eval Eval


Extension Module

Iterator Operation

Basic Specification

What's Gura?

Agenda

Basic Specification


Basic Specification

Function

Control Sequence

OOP

Collection

Scope Management


Basic Spec (1) Function

x = f(a => 3, b => 4)

f(a:number, b:number) = {a * a + b * b

}

x = f(3, 4)

Definition (1)

Call

Type can be specified

Named arguments


Basic Spec(1) Function

f(3) // a=3, b=[]f(3, 1) // a=3, b=[1]f(3, 1, 4, 1) // a=3, b=[1,4,1]

f(a, b*) = {// any job

}

Call

Definition (2) Variable-length argument that takes more than 0 value.

b+ takes more than 1 value.


Basic Spec(1) Function

my_loop(n) {block} = {while (n > 0) {

block()n -= 1

}}

my_loop(3) {println('hello')

}

Definition (3)

Call

Takes block expression as function object.{block?} means an optional block.


Basic Spec(2) Control Sequence

if (…) {

} elsif (…) {

} elsif (…) {

} else {

}

try {

} catch (…) {

} catch (…) {

}

for (…) {

}

repeat (…) {

}

while (…) {

}

Repeat Branch Exception

cross (…) {

}


Basic Spec(3) OOP

Fruit = class {__init__(name:string, price:number) = {

this.name = namethis.price = price

}Print() = {

printf('%s %d\n', this.name, this.price)}

}

fruit = Fruit('Orange', 90)fruit.Print()

Class Definition

Instantiation and Method Call

Constructor


Basic Spec(3) OOP

A = class {__init__(x, y) = {

// any jobs}

}

B = class(A) {__init__(x, y, z) = {|x, y|

// any jobs}

}

Inheritance

Arguments forbase class constructor


Basic Spec(4) Collection

a = [3, 1, 4, 1, 5, 9]b = ['zero', 'one', 2, 3, 'four', 5]

c = %{ `a => 3, `b => 1, `c => 4 }d = %{

'いぬ' => 'dog', 'ねこ' => 'cat'}

List

Dictionary


Basic Spec(5) Scope Management

create_counter(n:number) = {function {

n -= 1}

}

c = create_counter(4)c() // returns 3c() // returns 2c() // returns 1

Closure

Each function has lexical scope.


Extension Module

Iterator Operation

Basic Specification

What's Gura?

Agenda

Iterator Operation


Iterator Operation

Implicit Mapping

Member Mapping

Function

Repeat Control

Mapping

Generation

Iterator Operation: Mapping and Generation

Iterator

Iterator

Iterator

Iterator

Iterator


Gura's List and Iterator

List

Iterator

['apple', 'orange', 'grape']

('apple', 'orange', 'grape')

All the elements are stored in memory.

Each element would be generated.

Capable of random access

Only evaluation could make next element available


Gura's List and Iterator

Iterator

List Evaluation

Generation


Iterator Operation(1) Implicit Mapping

Generates iterator embedding function or operator

Functionor

Operator

argument values returned value

Implicit Mapping

Iterator

Iterator

Iterator

Iterator



f(a:number, b:number) = {a * b

}

Usual Function

f(a:number, b:number):map = {a * b

}

Mappable Function Specifies attribute :map



f(3, 4)Number

f([2, 3, 4], [3, 4, 5])List

f((2, 3, 4), (3, 4, 5))Iterator

f(5, (3, 4, 5))Number andIterator

Answer: 12

Answer: [6, 12, 20]

Answer: (6, 12, 20)

Answer: (15, 20, 25)



List

Scalar

Iterator

List

Others

Mapping process depends arguments' data type

IteratorCategorizedata types

Three rules to apply mapping



Generates an iteratorif at least one iterator exists in arguments.

Rule 1

Iterator

Iterator

Iterator

List

Iterator

Scalar

Iterator

Iterator

Iterator



Generates a list if there's no iterator andat least one list exists in arguments.

Rule 2

List

List

List

Scalar

List

List



Generates a scalarif only scalars exist in arguments.

Rule 3

Scalar

ScalarScalar


Iterator Operation(2) Member Mapping

Member Mapping

fruits[0] fruits[1] fruits[2]

name name name

Print() Print() Print()

price price price

List of instances

Generates an iterator to access instance members.



Member Mapping

fruits[0] fruits[1] fruits[2]

name name name

Print() Print() Print()

price price price

Iterator

Generates an iterator to access instance members.

fruits:*name

fruits:*price

fruits:*Print()

List of instances



sum = 0for (fruit in fruits) {

sum += fruit.price}println(sum)

println(fruits:*price.sum())

Prints summation of Fruit instance's member price.Task

Solution1 Using repeat control

Using Member MappingSolution2


Iterator Operation(3) Function

Function A function should return data sequenceby an iterator, not a list.

rtn = readlines('hello.c')

rtn = range(10)

Iterator to generate strings of each line

Iterator to generate numbers from 0 to 9

Design PolicyIterator


Iterator Operation(3) Function

rtn = readlines('hello.c'):list

rtn = range(10):list

List containing strings of each line

List containing numbers from 0 to 9

ListCall with attribute :listin order to get a listFunction Iterator


Iterator Operation(4) Repeat Control

Generate an iteratorfrom repeat control

Repeat Control

values

repeating job

x = for (…):iter {

}

Evaluation result ofrepeating job comes to be

the iterator's element

Specify attribute :iter

for

repeat

while

cross

Iterator



n = 0x = for (i in 0..5):iter {

n += i}

Nothing happens at this time

println(x)

Prints result: 0 1 3 6 10 15

Example of repeat control iterator



prime() = {p = []for (n in 2..):xiter {

if (!(n % p.each() == 0).or()) {p.add(n)n

}}

}

primes = prime()

Iterator to generate numbers (2, 3, 5, 7..)

Iterator to generate prime numbers


Extension Module

Iterator Operation

Basic Specification

What's Gura?

Agenda

Extension Module


Extension Module

Design Policy

Gura Interpreter itself should have as little dependencyon OS-specific functions and libraries as possible.It should extend capabilities by importing modules.

Gura Interpreter

ModuleModuleModule

ModuleModuleModule


Bundled Modules

GUIwxWidgets Tk SDL

Graphic Drawing

Cairo OpenGL FreeType

Image Data

JPEG PNG GIF BMP

ICO XPM PPM TIFF

Network

cURL Server

Text Processing

Regular Exp

yamlXMLCSV

markdown

Archive and Compression

TAR ZIP GZIP BZIP


Cooperation between Modules

Gura Interpreter

JPEG PNG GIF BMP ICO XPM PPM TIFF

Cairo OpenGL FreeType wxWidgets Tk SDL

image

Graphic DrawingDisplay Output

Read/Write of Image Data


Application Example

[ ID Photo Made at Home - Gura Shot ]

Creates ID photos by extracted faceimage from a file of digital camera.Outputs results in PDF and JPEG.

JPEG image Cairo image JPEG

wxWidgets

Reading File Composing Image Writing File

Output to Display


Thank you

www.gura-lang.org

Software

Introduction to Gura Programming Language