V (programming language): Difference between revisions

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==History==

The new language was created as a result of frustration with existing languages being used for personal projects.{{sfn|Chakraborty|Haldar|2023}} It was originally intended for personal use, but after being mentioned publicly and increasing interest, it was decided to make it public. V was initially created to develop a desktop messaging client named Volt.<ref name="hackaday"/> On public release, the compiler was written in V, and could [[Self-hosting (compilers)|compile itself]].{{Sfn|Rao|2021}}{{sfn|Chakraborty|Haldar|2023}} Key design goals in creating V were being easy to learn and use, higher readability, fast compiling, increased safety, efficient development, [[Cross-platform software|cross-platform]] usability, improved [[C (programming language)|C]] [[interoperability]], better [[Error detection and correction|error handling]], modern features, and more maintainable software.<ref name="MUO"/><ref name="analyticsindiamag"/><ref name="nasufi"/><ref>{{cite web |title=V language: simple like Go, small binary like Rust|url=https://techracho.bpsinc.jp/hachi8833/2021_03_09/89457/ |website=TechRacho |access-date=3 March 2021}}</ref>

V is released and developed through [[GitHub]],<ref>{{cite web |url=https://ossinsight.io/analyze/vlang/v#overview |title=GitHub Programming Languages (repository details) |via=[[Open-source software|OSS]] Insight using [[TiDB]] }}{{Dead link|date=July 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="hackaday"/> and maintained by developers and contributors internationally.{{Sfn|Rao|2021}} It is among the languages that have been listed on the [[TIOBE index]].<ref>{{cite web |title=TIOBE Index |url=https://www.tiobe.com/tiobe-index |publisher=[[TIOBE index|TIOBE]]|website=tiobe |archive-url=https://web.archive.org/web/20250411043213/https://www.tiobe.com/tiobe-index/|archive-date=11 April 2025|access-date=11 April 2025}}</ref>

[[File:Veasel.svg|thumb|Veasel is the official mascot of the V programming language<ref>{{cite web |url=https://github.com/vlang/v-mascot/ |title=V's official mascot |website=GitHub |access-date=8 November 2023}}</ref>]]

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===Safety===

V has policies to facilitate memory-safety, speed, and secure code,<ref name="MUO">{{cite web |last1=Galuh |first1=Rosa |title=A Brief Introduction to the V Language |url=https://www.makeuseof.com/v-language-brief-introduction |publisher=[[Valnet]]|website=MakeUseOf (MUO) |date=8 August 2022 |access-date=8 August 2022}}</ref><ref name="HA">{{cite web |last1=Abbas |first1=Hazem |title=Introduction to V Language and Desktop App Development |url=https://medevel.com/v-desktop-app-tutorial/ |website=medevel |date=5 August 2024 |access-date=3 January 2025}}</ref><ref name="hackaday"/> including various default features for greater program safety.<ref name="section"/><ref name="MUO"/>{{sfn|Chakraborty|Haldar|2023}} It employs [[bounds checking]], to guard against out of bounds use of [[Variable (computer science)|variables]]. Option/result [[Type system|types]] are used, where the option [[data type]] ({{code|?}}) can be represented by {{code|none}} (among possible choices) and the result type ({{code|!}}) can handle any returned errors. To ensure greater safety, error checking is mandatory. By default, the following are [[immutable]]: variables, structs, and [[Function (computer programming)|function]] [[Parameter (computer programming)|arguments]]. This includes string values are immutable, so elements cannot be mutated. Other protections, which are the default for the language, are: no use of [[undefined value]]s, [[variable shadowing]], [[null pointer]]s (unless marked as unsafe), or [[global variable]]s (unless enabled via flag).

=== Performance ===

V uses [[value type]]s and string buffers to reduce memory allocations.{{sfn|Rao|2021|p=7}}<ref>{{cite web |title=The V programming language is now open source |url=https://hub.packtpub.com/the-v-programming-language-is-now-open-sourced-is-it-too-good-to-be-true// |publisher=[[Packt Publishing]] |website=Packt Hub |date=24 June 2019 |access-date=24 June 2019}}</ref><ref name="MUO"/> The language can be compiled to human-readable C,<ref name="section"/>{{Sfn|Rao|2021}} and in terms of execution and compilation, it's considered to be as performant.<ref name="MUO"/><ref name="analyticsindiamag">{{cite web |first1=Ambika |last1=Choudhury |title=Meet V, The New Statically Typed Programming Language Inspired By Go & Rust|url=https://analyticsindiamag.com/meet-v-the-new-statistically-typed-programming-language-inspired-by-go-rust|website=Analytics India Magazine (AIM)|date=9 February 2022|access-date=7 July 2024}}</ref>{{sfn|Chakraborty|Haldar|2023}}

=== Memory management ===

V supports 4 memory management options:{{Sfn|Tsoukalos|2022}}<ref name="hackaday"/>{{sfn|Chakraborty|Haldar|2023}}

# Use of an optional [[Garbage collection (computer science)|garbage collection]] (GC), that can be disabled, for handling allocations, and is the default.

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===Source code translators===

V supports a [[source-to-source compiler]] (transpiler) and can translate C code into V.<ref name="analyticsindiamag"/><ref>{{cite web |first1=Sarah |last1=Schlothauer |website=JAXenter |date=|title=The trendy five: Blazing hot GitHub repos in June 2019| url=https://jaxenter.com/github-trending-june-2019-159622.html|archive-url=https://web.archive.org/web/20200217130047/https://jaxenter.com/github-trending-june-2019-159622.html |archive-date=17 February 2020 |access-date=1 July 2019}}</ref><ref name="nasufi"/>

Working translators are also being developed for Go, [[JavaScript]], and [[WebAssembly]].<ref>{{cite web |title=Convert Go to V with go2v|url=https://zenn.dev/tkm/articles/go2v-with-go-lsd|website=Zenn |date=26 January 2023 |access-date=26 January 2023}}</ref><ref>{{cite web |title=The V WebAssembly Compiler Backend|url=https://l-m.dev/cs/the_v_webassembly_compiler_backend/|archive-url=https://web.archive.org/web/20240708075458/https://l-m.dev/cs/the_v_webassembly_compiler_backend/ |website=l-m |date=26 February 2023 |archive-date=8 July 2024}}</ref>{{Sfn|Rao|2021}}

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== Syntax ==

=== Hello world ===

The [["Hello, World!" program]] in V:<ref name="MUO"/><ref name=":0">{{Cite web |title=V Documentation |url=https://docs.vlang.io/ |access-date=2025-08-25 |website=docs.vlang.io}} {{Free-content attribution|title = V Documentation| license statement URL =https://github.com/vlang/v?tab=MIT-1-ov-file| license=The MIT License|this = yes}}</ref>

The [["Hello, World!" program]] in V:<ref name="MUO"/>

<syntaxhighlight lang="v">

fn main() {

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=== Variables ===

Variables are immutable by default and are defined using {{code|1=:=}} and a value. Use the {{code|mut}} [[reserved word]] (keyword) to make them mutable. Mutable variables can be assigned to using {{code|1==}}:{{sfn|Rao|2021|pp=28-40}}<ref name=":0" />

<syntaxhighlight lang="V">

ax := 1

mut by := 2

by = 3

</syntaxhighlight>

Redeclaring a variable, whether in an inner scope or in the same scope, is not allowed:{{sfn|Rao|2021|pp=28-40}}<ref name=":0" />

<syntaxhighlight lang="V">

ax := 1

{

ax := 3 // error: redefinition of ax

}

ax := 2 // error: redefinition of ax

</syntaxhighlight>

=== Structs ===

Struct example:<ref name="Knott"/><ref name="section"/><ref name=":0" />

<syntaxhighlight lang="Vv">

struct PointFoo {

x number int

name string

y int

score f32

}

// Struct fields can be initialized by name

mut p := Point {

var1 := Foo {

x: 10

number: 21

y: 20

name: "baz"

score: 2.5

}

println(p.x) // Struct fields are accessed using a dot

// or by position

// Alternative literal syntax for structs with 3 fields or fewer

pvar2 := PointFoo{1050, 20"taz", 3.14}

assert p.x == 10

</syntaxhighlight>

=== Heap structs ===

Structs are allocated on the stack by default. To allocate a struct on the heap and get a reference to it, the {{code|&}} prefix can be used:{{sfn|Rao|2021}}

By default, structs are allocated on the stack. When structs are referenced by using the prefix {{code|1=&}} or have the heap attribute, they are allocated on the heap instead:{{sfn|Rao|2021}}<ref name=":0" />

<syntaxhighlight lang="Vv">

struct PointFoo {

x int

y number int

}

@[heap]

p := &Point{10, 10}

struct UserBaz {

// References have the same syntax for accessing fields

number f32

println(p.x)

}

// Structs that are referenced are heap allocated

var1 := &Foo{2}

// Baz is always heap allocated because of its [heap] attribute

var2 := Baz{4.5}

</syntaxhighlight>

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[[Method (computer programming)|Methods]] in V are functions defined with a receiver [[Parameter (computer programming)|argument]]. The receiver appears in its own argument list between the fn keyword and the method name. Methods must be in the same [[Modular programming|module]] as the receiver type.

The is_registeredenrolled_status method (below) has a receiver of type User{{code|1=Client}} named u{{code|1=x}}. The convention is not to use receiver names like self or this, but preferably a short name. For example:<ref name="Knott"/><ref name="nasufi"/><ref name=":0" /><syntaxhighlight lang="v">

struct Client {

enrolled bool

<syntaxhighlight lang="V">

struct User {

age int

}

fn (ux UserClient) is_registeredenrolled_status() bool {

return x.enrolled

return u.age > 16

}

println(Client{enrolled: true}.enrolled_status()) // true

user := User{

println(Client{enrolled: false}.enrolled_status()) // false

age: 10

}

println(user.is_registered()) // "false"

user2 := User{

age: 20

}

println(user2.is_registered()) // "true"

</syntaxhighlight>

=== Error handling ===

OptionalResult types aremay forrepresent typesan whicherror mayreturned representfrom nonea function. Result types mayare representdeclared anby errorprepending returned{{code|!}}: from a function.{{code|!Type}}

OptionOptional types aremay declaredrepresent by{{code|none}}. Option types prependingprepend {{code|?}} to the type name: ?Type. Result types use {{code|!?Type}}: !Type.<ref name="Knott"/><ref name="section"/>{{Sfn|Tsoukalos|2022}}<ref name=":0" />

<syntaxhighlight lang="V">

fn do_somethingsomething(st string) !string {

if st == "foo" { return "foo" }

return error("fooinvalid")

}

return error("invalid string")

}

ax := do_somethingsomething("foo") or { "default" } // ax will be "foo"

by := do_somethingsomething("barbaz") or { "default" } // by will be "default"

cz := do_somethingsomething("barbaz") or { panic("{err}") } // exitsz withwill errorexit "invalidwith string"an and a tracebackerror

println(ax)

println(by)

</syntaxhighlight>

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* {{Cite book |last1=Lyons |first1=Dakota "Kai" |date=April 13, 2022 |title=Beginning with V Programming |publisher=Independently Published |isbn=979-8801499963 |language=en |ref=none}}

* {{cite journal |last1=Tsoukalos |first1=Mihalis |date=May 2022 |title=Discover the V language |publisher=[[Linux Format]]| journal=Linux Format Magazine |issue=288 |issn=1470-4234}}

* {{Cite book |last1=Chakraborty |first1=Soubhik |last2=Haldar |first2=Subhomoy |date=December 6, 2023 |title=Randomness Revisited using the V Programming Language |publisher=[[Nova Science Publishers]] |isbn=979-8891133280 |language=en |ref=none |doi=10.52305/CVCN5241 |s2cid=265170755}}

* {{Cite book |last1=Trex |first1=Nova |date=24 December 2024 |title=V Programming: Building Robust and Efficient Software Systems |publisher=Wang Press |isbn=979-8304813778}}