Citrine (programming language): Difference between revisions

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{{short description|Programming language}}

{{Multiple issues|{{primary sources|date=August 2020}}{{COI|date=September 2020}}}}

{{Infobox programming language

| name = Citrine

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| paradigm = [[Object-oriented programming|Object-oriented]], [[Prototype-based programming|prototype-based]]

| year = 2014

| designer = Gabor de Mooij, Aavesh Jilani

| developer = Gabor de Mooij, Aavesh Jilani

| latest release version = 0.29.6

| latest release date = {{Start date and age|20142024|df=y1|5}}

| typing = [[dynamic typing|dynamic]]

| implementations = C

| influenced by = [[Smalltalk]], [[Self (programming language)|Self]]

| influenced =

| operating system = [[UnixCross-platform|Cross-platform (multi-platform)]]

| license = [[BSD licenses|BSD]]

| website = {{URL|citrine-lang.org}}

| file ext = .ctr

}}

'''Citrine''' is a general -purpose [[programming language]] for [[UnixCross-like]]platform|various operating systems]]. It focuses on readability and maintainability. Readability is achieved by syntactic and conceptual minimalism. The language is heavily inspired by [[Smalltalk]] and [[Self (programming language)|Self]] but has some very distinctive features. Like Smalltalk, Citrine treats everything as an object and focuses on sending messages to these objects. However, unlike Smalltalk, Citrine lacks the concept of a class. In this regard, Citrine is more like Self and [[JavaScript]] because it uses [[Prototype-based programming|prototypes]]. The combination of Smalltalk -like messages and prototypes is what makes Citrine unique.

Since version 0.7, Citrine has focused on using forms based on various natural languages instead of just English, improving usability for users of other languages, thereby reducing programming effort and incidence of bugs. As such, Citrine 0.7 and later include a feature to transform code between natural languages.

==Syntax==

Citrine has a very limited syntax and it's very closely related to Smalltalk. Everything in Citrine is an ''object'',. thereThere are 5 literals:

* {{code|Nil}}

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* <code>{ ...params.. ...block of code... }</code>

The code block literal uses a ''pipe'' symbol ⟨|⟩ to separate the parameters from the logic '|',; if there are no

parameters, the backslash should be used instead '\'.

Citrine only supports full -line comments, commentswhich start with a '⟨#'⟩.

A Citrine program is basically a sequence of messages sent to objects. For instance, to calculatedetermine thewhether factorial5 ofis thean even number 5, the message 'factorialeven?' is sent to the number 5.

<sourcesyntaxhighlight lang="smalltalk">

5 even?

5 factorial.

</syntaxhighlight>

</source>

This is called a ''unary'' message, because it takes no arguments. A ''binary'' message is always a single UTF-8 character; this differs from Smalltalk, where there is a fixed set of binary messages. Here is an example:

<sourcesyntaxhighlight lang="smalltalk">

6 + 7.

</syntaxhighlight>

</source>

Here a binary message '+' is sent to number 6, with the argument of thisthe binary message isbeing '7',. thisThis will resultresults in athe new number object '13'. Assigning the outcome of this operation to a variable uses the assignment operator: :=.

<sourcesyntaxhighlight lang="smalltalk">

total := money + debt.

</syntaxhighlight>

</source>

Also note thatAdditionally, each line in a Citrine program ends with a dot, just likeas in Smalltalk. BesidesAlong with unary and binary messages, Citrine offers ''keyword messages'', which take arguments interspersed with the message itself just like Smalltalk and [[Objective-C]].

<sourcesyntaxhighlight lang="smalltalk">

3☞ x := Number between: 1 and: 5.

</syntaxhighlight>

</source>

The code snippet above will return a boolean object ''True''.

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Just like Smalltalk, control flow in Citrine is implemented by strategic use of messages. For instance, writing a conditional statement requires sending a block of code to a boolean.

<sourcesyntaxhighlight lang="smalltalk">

(money > price) ifTruetrue: { Pen✎ write: 'Yes, you can afford this'. }.

</syntaxhighlight>

</source>

Likewise, a for-loop is written as:

<sourcesyntaxhighlight lang="smalltalk">

1 to: 10 step: 1 do: { :step Pen✎ write: 'this is step:' + step. } × 10.

</syntaxhighlight>

</source>

To break out of a loop in Citrine, one has tomust send the message 'break' to a boolean,. thisThis allows a conditional break from a loop without having to factor out the break conditions:

Besides for-loops, Citrine features each-loops, while-loops and a simple times loop, the latter uses the binary message '*'.

<source lang="smalltalk">

7 times: { :step Pen write: 'this is step:' + step. }.

</source>

To break out of a loop in Citrine one has to send the message 'break' to a boolean, this allows a conditional break from a loop without having to factor out the break conditions:

<sourcesyntaxhighlight lang="smalltalk">

{ :i

#0-4

(i = 43) break.

0 to: 10 step: 1 do: { :i

Pen ✎ write: 'iteration #' + i, brk.

} * 5.

(i = 4) break.

</syntaxhighlight>

}.

</source>

==Pipelines==

Unlike Smalltalk, Citrine has no semi-colon to send a message to the original receiver. Instead, Citrine has a comma token ',' used to chain keyword messages, thiswhich allows writing Unix-like ''[[Pipeline (Unix)|pipelines]]''. The following code uses a pipeline-like syntax to replace all the 'o' characters with zeroes, the resulting string would be something like: '1010101...'.

<sourcesyntaxhighlight lang="smalltalk">

onesAndZeroes := '1o1o1o1o1o1' split: 'o', map: mapUp, join: '0'.

</syntaxhighlight>

</source>

==Prototypes==

The biggest difference from Smalltalk is the use of prototypes. Citrine does not have a concept of a class, itbut only knows about objects. An object is created using the new message:

<sourcesyntaxhighlight lang="smalltalk">

cat := Object new.

</syntaxhighlight>

</source>

This object can be made to respond to messages by ordering the object to listen to events., Thissimilar isto kindadding ofmethods similarin tolanguages like [[Java (programming language)|Java]]:

adding methods in languages like [[Java (programming language)|Java]]:

<sourcesyntaxhighlight lang="smalltalk">

cat on: 'meow' do: {

Pen write: 'meow!'.

}.

</syntaxhighlight>

</source>

As stated above, inheritance is based on prototypes. To derive an object from another object, the new message must be sent to the object to be extended:

<sourcesyntaxhighlight lang="smalltalk">

☞ Animal := Object new.

Animal on: 'makeSound' do: {

Pen✎ write: '?'.

}.

☞ Cat := Animal new.

Cat on: 'makeSound' do: {

Pen✎ write: 'meow!'.

}.

☞ Tom := Cat new.

Tom makeSound.

</syntaxhighlight>

</source>

==Unicode==

Citrine uses UTF-8 unicode extensively, both objects and messages can consist of unicode symbols. All string length are calculated using UTF-8. Citrine distinguishes string length and size in bytes:

<sourcesyntaxhighlight lang="smalltalk">

'text' length.

</syntaxhighlight>

</source>

returns the length of the string in UTF-8 code pointespoints, while:

<sourcesyntaxhighlight lang="smalltalk">

'text' bytes.

</syntaxhighlight>

</source>

returns the number of bytes.

Line 145 ⟶ 141:

Citrine uses [[dynamic scoping]] instead of [[lexical scoping]]. Thus, there is no need for [[dependency injection]] or global variables, but it might be harder to reason about than lexical scope. This is similar in programming languages like [[Emacs Lisp]] and [[BASIC]]. In code blocks the ''var'' keyword needs to be used to declare a local variable.

The following demonstration makes the Mailer object available in the module:

Demonstration:

<sourcesyntaxhighlight lang="smalltalk">

Application := {

var☞ mailer := Mailer new. #make mailer available to all modules

module run. #mailer is now available in module

}.

</syntaxhighlight>

</source>

==See also==

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* [http://fll.presidentbeef.com/lang/citrine/ demo in new programming languages community]

* [https://jaxenter.com/citrine-a-new-all-purpose-programming-language-for-unixoid-systems-123558.html Citrine Review Jaxenter]

* [https://www.reddit.com/r/programming/comments/42gqu4/new_programming_language_citrine/ Announcement on ReddisReddit]

* [http://www.infoworld.com/article/3028559/application-development/citrine-borrows-from-ruby-javascript-c-for-object-oriented-programming.html InfoWorld interview]

* [https://web.archive.org/web/20221108082728/https://www.tiobe.com/tiobe-index/ Tiobe Index]

==External links==

* {{Official website|citrine-lang.org}}

* [https://github.com/gabordemooij/citrine source code], Source code on githubGitHub

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