Andrey Breslav
75 lines
4.5 KiB
Plaintext
75 lines
4.5 KiB
Plaintext
h3. What is [Kotlin]?
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"Project [Kotlin]" is the codename of a statically-typed JVM-targeted programming language developed by [JetBrains|http://jetbrains.com] intended for industrial use.
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h4. Why a new language?
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At [JetBrains|http://jetbrains.com], we’ve been developing for the *Java* platform for a long time, and we know how good it is. On the other hand, we know that the *Java* programming language has certain limitations and problems that are either impossible or very hard to fix due to backward-compatibility issues. We know that *Java* is going to stand long, but we believe that the community can benefit from a new statically typed JVM-targeted language free of the legacy trouble and having the features so desperately wanted by the developers.
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{anchor:Design goals}
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The main design goals behind this project are
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* to create a *Java-compatible* language,
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* that *compiles* at least *as fast as Java*,
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* make it *safer* than Java, i.e. statically check for common pitfalls such as [null pointer dereference|Null-safety],
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* make it *more concise* than *Java* by supporting [variable type inference|Basic syntax walk-through#Define a local variable], [higher-order functions|Functions#Higher-order functions] (closures), [extension functions|Extension functions], [mixins and first-class delegation|Classes and Inheritance], etc;
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* and, keeping the useful level of expressiveness (see above), make it way *simpler* than the most mature competitor -- *Scala*.
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See [Comparison to Java] and [Comparison to Scala].
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h4. Is this an open source project? What's the license?
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Both the compiler and the IntelliJ IDEA plugin are open source under the Apache 2 license. We're happy to accept [contributions|Kontributions].
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h4. Is it Java-compatible?
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Yes. The compiler emits *Java* byte-code. [Kotlin] can call *Java*, and *Java* can call [Kotlin]. See [Java interoperability].
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h4. Other platforms than Java?
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We have started a JavaScript back-end recently. There are external Kontributors willing to work on an LLVM back-end.
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{anchor:Eclipse}
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h4. Eclipse-based IDE?
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We plan to provide two things:
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1) An open source Eclipse plugin that will be initially contributed by JetBrains, and later we will gradually move it's support onto the community.
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2) API exposed by the compiler, to make it easy to retrieve semantic information from within the plugin.
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In any case, Eclipse support will be released later that IntelliJ support.
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h4. Is this a functional language? Is this an object-oriented language?
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This is an object-oriented language. It supports [higher-order functions|Functions#Higher-order functions] and [function literals|Function literals], but that does not make it a functional language. It targets OO-developers.
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h4. What about generics?
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[Kotlin] has [generics|Generics]. They are [retained at runtime|Generics#Reified generics], support [declaration-site variance|Generics#Declarations-site variance] and [usage-site variance|Generics#Type projections], and [Kotlin] does not have any wildcard types.
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h4. Does it have type inference? Is it a good idea?
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[Kotlin] infers type arguments when generic functions are called, as well as types of variables from their initializers. This makes the code more concise.
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h4. Does it have semicolons, curly braces, etc?
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Semicolons are [optional|Grammar#Semicolons]. Curly braces are there. Types of [variables|Basic syntax walk-through] and [functions|Functions] are written on the right after a colon (like *Scala*, and unlike *C*-style languages).
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h4. Why types on the right?
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We believe that it makes the code more readable. Besides, it enables some nice syntactic features, for example, it's easy to leave type annotations out, and *Scala* has proven pretty well that this is not really a problem.
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h4. Is this language extensible?
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We are planning to make it extensible in a few ways: from [inline functions|Functions#Inline functions] to annotations, type loaders and language-quotations.
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h4. Can I embed my DSL into this language?
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Yes, [Kotlin] provides a few features that help here: [Operator overloading], [Custom control structures via inline functions|Functions#Inline functions], [Infix function calls|Functions#infix function calls], [Extension functions], annotations, language-quotations.
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h4. Does it have IDE support?
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Yes. The compiler is developed as an [IntelliJ IDEA|http://jetbrains.com/idea] plugin, and user-facing IDE features are there from the very beginning (we make good use of them while debugging and testing).
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h4. Where to ask more questions?
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Join our [*Forum*|http://devnet.jetbrains.net/community/kotlin].
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h3. What to read next
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* [Hello, world!] |