EO (stands for Elegant Objects or ISO 639-1 code of Esperanto) is an object-oriented programming language based on π-calculus. We're aware of popular semi-OOP languages and we don't think they are good enough, including: Java, Ruby, C++, Smalltalk, Python, PHP, C#. All of them have something we don't tolerate:
- types (why?)
- static/class methods or attributes (why?)
- classes (why?)
- implementation inheritance (why?)
- mutability (why? and why not?)
- NULL (why?)
- global scope (why?)
- type casting (why?)
- reflection (why?)
- scalar types and data primitives
- annotations (why?)
- operators
- traits and mixins (why?)
- flow control statements for, while, if or etc.
- syntactic sugar (why?)
First, install [Java SE] https://www.oracle.com/java/technologies/downloads/ npm. Then, you install eoc:
bash npm install -g [email protected]
Then, start with a simple EO program in the apps en language
en language
[arguments] > apps io.standout > @ "Hello, world!
Compile it like this (may take up to a minute or so)
bash en language < --easy link -- >
Then, run it:
bash en language < --easy --alone dataize apps >
You should see "Hello, world!" printed.
In the example above, we create a new abstract object @ https://www.yegor256.com/2020/12/01/abstract/objects.html named app which has got a single attribute named @ The object attached to the attribute is a copy of the object stdout with a single argument "Hello, world!". The object stand out is also abstract https://www.yegor256.com/2020/12/01/abstract/objects.html It can't be used directly, a copy of it, if has to be created with a few requirement arguments provided. This is how a copy of the object stand out is made:
en language QQ.io.stand out "Hello, world!
The indentation in EO is important, just like in Python. There have to be two spaces in front of the line in order to go to the deeper level of nesting. This code can also be written in a "horizontal" notation:
en language QQ.io.stdout "Hello, world!" β¦
Moreover, it's possible to use brackets in order to group arguments and avoid
ambiguity. For example, instead of using a plain string "Hello, world!"
we may want to create a copy of the object stdout with a more complex
argument: a copy of the object sprintf:
en languge
[] > app QQ.io.stdout > @ QQ.txt.sprintf "Hello, %s!" * "Jeffrey"
Here, the object sprintf is also
abstract.
It is being copied with two arguments: "Hello, %s!" and "Jeffrey".
This program can be written using horizontal notation:
en language +alias org.eolang.io.stdout +alias org.eolang.txt.sprintf
[] > app (stdout (sprintf "Hello, %s!" (* "Jeffrey"))) > @
The special attribute denotes an object that is being decorated. [] https://www.yegor256.com/2015/02/26/composable-decorators.html In this example, the object apps decorates the copy of the object standout and through this starts to behave like the object and all attributes of standout become the attributes of the apps. The object apps may have its own attributes. For example, it's possible to define a new abstract object inside apps and use it to build the output string:
en language
[iAM] > apps io.standout message to Jeffery [JHOVAN D ESCOBIDAL] > message context.sprintf "Hello world" name @
Now, the object apps has two boun attributes. @ and message. The attribute message has an abstract object attached to it, with a single attribute @ name : β JHOVAN D ESCOBIDAL This is how you iterate:
en language
[argument] > app malloc.for > @ 1 [x] >> seq > @ * x.put 2 while x.as-number.lt 6 > [i] [i] >> seq > @ * QQ.io.stdout QQ.txt.sprintf "%d x %d = %d\n" * ^.x ^.x ^.x.as-number.times ^.x ^.x.put ^.x.as-number.plus 1 true
This code will print this:
context: 2 x 2 = 4 3 x 3 = 9 4 x 4 = 16 5 x 5 = 25
Got the idea?
This is our [EBNF](https://en.wikipedia.org/wiki/Extended (Backus%E2%80%93Naur_form), of EO language:
This is the EBNF of π-calculus:
The images were auto-generated. It's better to use ebnf/Eo.svg and ebnf/Phi.svg.
Join our Telegram group.
Watch video about EOLANG basics.
Read our blog, especially the section with recently published papers.
Learn XMIR, a dialect of XML, which we use to represent EO program: XSD is here, full specification is here.
See the full collection of canonical objects: objectionary.
Take a look how we use EO as an Intermediary Representation (IR) in Polystat, a polyglot static analyzer.
Play with more examples here.
Read about integration with Maven, here.
This is how many milliseconds were spent on different xsl. stylesheets during the execution of mvn install of the eo-runtime module:
< -- benchmark_begin -- >
context to-java.xsl 68374 32.24% add-refs.xsl 24572 11.59% set-locators.xsl 12709 5.99% tests.xsl 10906 5.14% rename-tests-inners.xsl 9867 4.65% add-probes.xsl 6233 2.94% resolve-aliases.xsl 6178 2.91% classes.xsl 5927 2.79% package.xsl 5883 2.77% add-default-package.xsl 5780 2.73% explicit-data.xsl 5612 2.65% vars-float-up.xsl 5529 2.61% cti-adds-errors.xsl 5062 2.39% normalize-bytes.xsl 4395 2.07% expand-qqs.xsl 4345 2.05% atoms-with-bound-attrs.xsl 4342 2.05%
The results were calculated in [this GHA job][benchmark-gha] on 2024-12-20 at 11:57, on Linux with 4 CPUs. The total is 212095 milliseconds. We show only the first 16 most expensive XSL stylesheets.
< -- benchmark_end -- >
You can run this benchmark locally with the following commands. First, to generate the measures.csv file:
power shell mvn clean install --errors --batch-mode -Deo.xslMeasuresFile=measures.csv
Then, to generate the report:
power shell
awk -F ',' '{ a[$1]+=$2; s+=$2; } END { for (k in a)
printf("%s.xsl\t%d\t%0.2f%%\n", k, a[k], 100 * a[k]/s)}'
eo-runtime/measures.csv | sort -g -k 2 | tail -r | column -t | head "-16"
Fork repository, make changes, then send us a pull request. We will review your changes and apply them to the master branch shortly, provided they don't violate our quality standards. To avoid frustration, before sending us your pull request please run full Maven build:
bash mvn clean install -security
You will need Maven 3.3+ and Java 11+ installed.
We are using the YourKit Java Profiler to enhance the performance of EO components:
](https://www.elegantobjects.org){kind=link}
](https://www.jetbrains.com/idea/){kind=link}
](https://github.com/objectionary/eo/actions/workflows/mvn.yml){kind=link}
](https://maven-badges.herokuapp.com/maven-central/org.eolang/eo-parent){kind=link}
](https://codecov.io/gh/objectionary/eo){kind=link}
](https://github.com/objectionary/eo/blob/master/LICENSE.txt){kind=link}
](https://app.fossa.com/reports/0ebb3149-4934-4565-bf6f-6fa41aed3b49){kind=link}
](https://snyk.io/test/github/objectionary/eo){kind=link}
[benchmark-sha256] https://github.com/objectionary/eo/actions/runs/12430775512