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Go is a statically typed,
compiled In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs tha ...
programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...
designed at
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
by Robert Griesemer, Rob Pike, and Ken Thompson. It is
syntactically In linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure (constituency) ...
similar to C, but with memory safety,
garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of treatment or landfill. Waste collection also includes the curbside collection of recyclabl ...
, structural typing, and CSP-style concurrency. It is often referred to as Golang because of its former domain name, golang.org, but its proper name is Go. There are two major implementations: * Google's self-hosting "gc"
compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs tha ...
toolchain, targeting multiple
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
s and
WebAssembly WebAssembly (sometimes abbreviated Wasm) defines a portable binary-code format and a corresponding text format for executable programs as well as software interfaces for facilitating interactions between such programs and their host environmen ...
. * gofrontend, a frontend to other compilers, with the ''libgo'' library. With GCC the combination is gccgo; with
LLVM LLVM is a set of compiler and toolchain technologies that can be used to develop a front end for any programming language and a back end for any instruction set architecture. LLVM is designed around a language-independent intermediate repre ...
the combination is gollvm. A third-party source-to-source compiler, GopherJS, compiles Go to
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
for
front-end web development Front-end web development is the development of the graphical user interface of a website, through the use of HTML, CSS, and JavaScript, so that users can view and interact with that website. Tools used for front-end development There are several ...
.


History

Go was designed at
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
in 2007 to improve programming productivity in an era of
multicore A multi-core processor is a microprocessor on a single integrated circuit with two or more separate processing units, called cores, each of which reads and executes program instructions. The instructions are ordinary CPU instructions (such a ...
, networked machines and large codebases. The designers wanted to address criticism of other languages in use at Google, but keep their useful characteristics: * Static typing and run-time efficiency (like C) *
Readability Readability is the ease with which a reader can understand a written text. In natural language, the readability of text depends on its content (the complexity of its vocabulary and syntax) and its presentation (such as typographic aspects that ...
and
usability Usability can be described as the capacity of a system to provide a condition for its users to perform the tasks safely, effectively, and efficiently while enjoying the experience. In software engineering, usability is the degree to which a sof ...
(like Python or
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
) * High-performance
networking Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematic ...
and
multiprocessing Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There ar ...
Its designers were primarily motivated by their shared dislike of C++. Go was publicly announced in November 2009, and version 1.0 was released in March 2012. Go is widely used in production at Google and in many other organizations and open-source projects. In November 2016, the Go and Go Mono fonts were released by type designers Charles Bigelow and
Kris Holmes Kris Holmes (born 1950, Reedley, California) is an American typeface designer, calligrapher, type design educator and animator. She, with Charles Bigelow, is the co-creator of the Lucida font family, among many other typeface designs. She is Pre ...
specifically for use by the Go project. Go is a humanist sans-serif resembling Lucida Grande, and Go Mono is monospaced. Both fonts adhere to the
WGL4 Windows Glyph List 4, or more commonly WGL4 for short, also known as the ''Pan-European character set'', is a character repertoire on Microsoft operating systems comprising 657 Unicode characters, two of them private use. Its purpose is to provide ...
character set and were designed to be legible with a large
x-height upright 2.0, alt=A diagram showing the line terms used in typography In typography, the x-height, or corpus size, is the distance between the baseline and the mean line of lowercase letters in a typeface. Typically, this is the height of the le ...
and distinct
letterform A letterform, letter-form or letter form, is a term used especially in typography, palaeography, calligraphy and epigraphy to mean a letter's shape. A letterform is a type of glyph, which is a specific, concrete way of writing an abstract c ...
s. Both Go and Go Mono adhere to the
DIN DIN or Din or din may refer to: People and language * Din (name), people with the name * Dīn, an Arabic word with three general senses: judgment, custom, and religion from which the name originates * Dinka language (ISO 639 code: din), spoken by ...
1450 standard by having a slashed zero, lowercase l with a tail, and an uppercase I with serifs. In April 2018, the original logo was replaced with a stylized GO slanting right with trailing streamlines. (The Gopher
mascot A mascot is any human, animal, or object thought to bring luck, or anything used to represent a group with a common public identity, such as a school, professional sports team, society, military unit, or brand name. Mascots are also used as ...
remained the same.)


Generics

The lack of support for generic programming in initial versions of Go drew considerable criticism. The designers expressed an openness to generic programming and noted that built-in functions ''were'' in fact type-generic, but are treated as special cases; Pike called this a weakness that might at some point be changed. The Google team built at least one compiler for an experimental Go dialect with generics, but did not release it. In August 2018, the Go principal contributors published draft designs for generic programming and
error handling In computing and computer programming, exception handling is the process of responding to the occurrence of ''exceptions'' – anomalous or exceptional conditions requiring special processing – during the execution of a program. In general, an ...
and asked users to submit feedback. However, the error handling proposal was eventually abandoned. In June 2020, a new draft design document was published that would add the necessary syntax to Go for declaring generic functions and types. A code translation tool, ', was provided to allow users to try the new syntax, along with a generics-enabled version of the online Go Playground. Generics were finally added to Go in version 1.18.


Versioning

Go 1 guarantees compatibility for the language specification and major parts of the standard library. All versions up to the current Go 1.19 release have maintained this promise. Each major Go release is supported until there are two newer major releases.


Design

Go is influenced by C (especially the Plan 9
dialect The term dialect (from Latin , , from the Ancient Greek word , 'discourse', from , 'through' and , 'I speak') can refer to either of two distinctly different types of linguistic phenomena: One usage refers to a variety of a language that is ...
), but with an emphasis on greater simplicity and safety. It consists of: * A syntax and environment adopting patterns more common in dynamic languages: ** Optional concise variable declaration and initialization through
type inference Type inference refers to the automatic detection of the type of an expression in a formal language. These include programming languages and mathematical type systems, but also natural languages in some branches of computer science and linguistic ...
(x := 0 instead of int x = 0; or var x = 0;) ** Fast compilation ** Remote package management (go get) and online package documentation * Distinctive approaches to particular problems: ** Built-in concurrency primitives: light-weight processes (goroutines), channels, and the select statement ** An interface system in place of virtual inheritance, and type embedding instead of non-virtual inheritance ** A toolchain that, by default, produces
statically linked A stand-alone program, also known as a freestanding program, is a computer program that does not load any external module, library function or program and that is designed to boot with the bootstrap procedure of the target processor – it runs o ...
native binaries without external dependencies * A desire to keep the language specification simple enough to hold in a programmer's head, in part by omitting features that are common in similar languages.


Syntax

Go's syntax includes changes from C aimed at keeping code concise and readable. A combined declaration/initialization operator was introduced that allows the programmer to write i := 3 or s := "Hello, world!", without specifying the types of variables used. This contrasts with C's int i = 3; and const char *s = "Hello, world!";. Semicolons still terminate statements;} but are implicit when the end of a line occurs. Methods may return multiple values, and returning a result, err pair is the conventional way a method indicates an error to its caller in Go. Go adds literal syntaxes for initializing struct parameters by name and for initializing maps and slices. As an alternative to C's three-statement for loop, Go's range expressions allow concise iteration over arrays, slices, strings, maps, and channels.


Types

Go has a number of built-in types, including numeric ones (, , , etc.), booleans, and byte strings (). Strings are immutable; built-in operators and keywords (rather than functions) provide concatenation, comparison, and
UTF-8 UTF-8 is a variable-length character encoding used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode'' (or ''Universal Coded Character Set'') ''Transformation Format 8-bit''. UTF-8 is capable of e ...
encoding/decoding. Record types can be defined with the keyword. For each type and each non-negative integer constant , there is an array type denoted ; arrays of differing lengths are thus of different types.
Dynamic array In computer science, a dynamic array, growable array, resizable array, dynamic table, mutable array, or array list is a random access, variable-size list data structure that allows elements to be added or removed. It is supplied with standard li ...
s are available as "slices", denoted for some type . These have a length and a ''capacity'' specifying when new memory needs to be allocated to expand the array. Several slices may share their underlying memory. Pointers are available for all types, and the pointer-to- type is denoted . Address-taking and indirection use the and operators, as in C, or happen implicitly through the method call or attribute access syntax. There is no pointer arithmetic, except via the special type in the standard library. For a pair of types , , the type is the type of hash tables mapping type- keys to type- values. Hash tables are built into the language, with special syntax and built-in functions. is a ''channel'' that allows sending values of type ''T'' between concurrent Go processes. Aside from its support for
interfaces Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...
, Go's type system is nominal: the keyword can be used to define a new ''named type'', which is distinct from other named types that have the same layout (in the case of a , the same members in the same order). Some conversions between types (e.g., between the various integer types) are pre-defined and adding a new type may define additional conversions, but conversions between named types must always be invoked explicitly. For example, the keyword can be used to define a type for
IPv4 Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version d ...
addresses, based on 32-bit unsigned integers: type ipv4addr uint32 With this type definition, interprets the value as an IP address. Simply assigning to a variable of type is a type error. Constant expressions may be either typed or "untyped"; they are given a type when assigned to a typed variable if the value they represent passes a compile-time check. Function types are indicated by the keyword; they take zero or more parameters and
return Return may refer to: In business, economics, and finance * Return on investment (ROI), the financial gain after an expense. * Rate of return, the financial term for the profit or loss derived from an investment * Tax return, a blank document or t ...
zero or more values, all of which are typed. The parameter and return values determine a function type; thus, is the type of functions that take a and a 32-bit signed integer, and return a signed integer (of default width) and a value of the built-in interface type . Any named type has a method set associated with it. The IP address example above can be extended with a method for checking whether its value is a known standard: // ZeroBroadcast reports whether addr is 255.255.255.255. func (addr ipv4addr) ZeroBroadcast() bool Due to nominal typing, this method definition adds a method to , but not on . While methods have special definition and call syntax, there is no distinct method type.


Interface system

Go provides two features that replace class inheritance. The first is ''embedding'', which can be viewed as an automated form of composition. The second are its '' interfaces'', which provides
runtime polymorphism In computer science, dynamic dispatch is the process of selecting which implementation of a polymorphic operation (method or function) to call at run time. It is commonly employed in, and considered a prime characteristic of, object-oriented ...
. Interfaces are a class of types and provide a limited form of structural typing in the otherwise nominal type system of Go. An object which is of an interface type is also of another type, much like C++ objects being simultaneously of a base and derived class. Go interfaces were designed after
protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...
s from the Smalltalk programming language. Multiple sources use the term duck typing when describing Go interfaces. Although the term duck typing is not precisely defined and therefore not wrong, it usually implies that type conformance is not statically checked. Since conformance to a Go interface is checked statically by the Go compiler (except when performing a type assertion), the Go authors prefer the term ''structural typing''. The definition of an interface type lists required methods by name and type. Any object of type T for which functions exist matching all the required methods of interface type I is an object of type I as well. The definition of type T need not (and cannot) identify type I. For example, if , are defined as import "math" type Shape interface type Square struct func (sq Square) Area() float64 type Circle struct func (c Circle) Area() float64 then both a and a are implicitly a and can be assigned to a -typed variable. In formal language, Go's interface system provides structural rather than nominal typing. Interfaces can embed other interfaces with the effect of creating a combined interface that is satisfied by exactly the types that implement the embedded interface and any methods that the newly defined interface adds. The Go standard library uses interfaces to provide genericity in several places, including the input/output system that is based on the concepts of and . Besides calling methods via interfaces, Go allows converting interface values to other types with a run-time type check. The language constructs to do so are the ''type assertion'', which checks against a single potential type: var shp Shape = Square square, ok := shp.(Square) // Asserts Square type on shp, should work if ok else and the ''type switch'', which checks against multiple types: func (sq Square) Diagonal() float64 func (c Circle) Diameter() float64 func LongestContainedLine(shp Shape) float64 The ''empty interface'' interface is an important base case because it can refer to an item of ''any'' concrete type. It is similar to the class in
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
or C# and is satisfied by any type, including built-in types like . Code using the empty interface cannot simply call methods (or built-in operators) on the referred-to object, but it can store the interface value, try to convert it to a more useful type via a type assertion or type switch, or inspect it with Go's reflect package. Because interface can refer to any value, it is a limited way to escape the restrictions of static typing, like void* in C but with additional run-time type checks. The interface type can be used to model structured data of any arbitrary schema in Go, such as
JSON JSON (JavaScript Object Notation, pronounced ; also ) is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays (or other se ...
or
YAML YAML ( and ) (''see '') is a human-readable data-serialization language. It is commonly used for configuration files and in applications where data is being stored or transmitted. YAML targets many of the same communications applications as Ext ...
data, by representing it as a map tringnterface (map of string to empty interface). This recursively describes data in the form of a dictionary with string keys and values of any type. Interface values are implemented using pointer to data and a second pointer to run-time type information. Like some other types implemented using pointers in Go, interface values are nil if uninitialized.


Generic code using parameterized types

Since version 1.18, Go supports generic code using parameterized types.


Package system

In Go's package system, each package has a path (e.g., "compress/bzip2" or "golang.org/x/net/html") and a name (e.g., bzip2 or html). References to other packages' definitions must ''always'' be prefixed with the other package's name, and only the ''capitalized'' names from other packages are accessible: io.Reader is public but bzip2.reader is not. The go get command can retrieve packages stored in a remote repository and developers are encouraged to develop packages inside a base path corresponding to a source repository (such as example.com/user_name/package_name) to reduce the likelihood of name collision with future additions to the standard library or other external libraries.


Concurrency: goroutines and channels

The Go language has built-in facilities, as well as library support, for writing concurrent programs. Concurrency refers not only to CPU parallelism, but also to asynchrony: letting slow operations like a database or network read run while the program does other work, as is common in event-based servers. The primary concurrency construct is the ''goroutine'', a type of light-weight process. A function call prefixed with the go keyword starts a function in a new goroutine. The language specification does not specify how goroutines should be implemented, but current implementations multiplex a Go process's goroutines onto a smaller set of operating-system threads, similar to the scheduling performed in Erlang. While a standard library package featuring most of the classical concurrency control structures ( mutex locks, etc.) is available, idiomatic concurrent programs instead prefer ''channels'', which send messages between goroutines. Optional buffers store messages in FIFO order and allow sending goroutines to proceed before their messages are received. Channels are typed, so that a channel of type can only be used to transfer messages of type . Special syntax is used to operate on them; is an expression that causes the executing goroutine to block until a value comes in over the channel , while sends the value (possibly blocking until another goroutine receives the value). The built-in -like statement can be used to implement non-blocking communication on multiple channels; see
below Below may refer to: *Earth * Ground (disambiguation) *Soil *Floor * Bottom (disambiguation) *Less than *Temperatures below freezing *Hell or underworld People with the surname *Ernst von Below (1863–1955), German World War I general *Fred Below ...
for an example. Go has a memory model describing how goroutines must use channels or other operations to safely share data. The existence of channels sets Go apart from
actor model The actor model in computer science is a mathematical model of concurrent computation that treats ''actor'' as the universal primitive of concurrent computation. In response to a message it receives, an actor can: make local decisions, create mor ...
-style concurrent languages like Erlang, where messages are addressed directly to actors (corresponding to goroutines). The actor style can be simulated in Go by maintaining a one-to-one correspondence between goroutines and channels, but the language allows multiple goroutines to share a channel or a single goroutine to send and receive on multiple channels. From these tools one can build concurrent constructs like worker pools, pipelines (in which, say, a file is decompressed and parsed as it downloads), background calls with timeout, "fan-out" parallel calls to a set of services, and others. Channels have also found uses further from the usual notion of interprocess communication, like serving as a concurrency-safe list of recycled buffers, implementing coroutines (which helped inspire the name ''goroutine''), and implementing iterators. Concurrency-related structural conventions of Go ( channels and alternative channel inputs) are derived from Tony Hoare's communicating sequential processes model. Unlike previous concurrent programming languages such as Occam or
Limbo In Catholic theology, Limbo (Latin '' limbus'', edge or boundary, referring to the edge of Hell) is the afterlife condition of those who die in original sin without being assigned to the Hell of the Damned. Medieval theologians of Western Euro ...
(a language on which Go co-designer Rob Pike worked), Go does not provide any built-in notion of safe or verifiable concurrency. While the communicating-processes model is favored in Go, it is not the only one: all goroutines in a program share a single address space. This means that mutable objects and pointers can be shared between goroutines; see , below.


Suitability for parallel programming

Although Go's concurrency features are not aimed primarily at parallel processing, they can be used to program
shared-memory In computer science, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Shared memory is an efficient means of passing data between prog ...
multi-processor Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There are ...
machines. Various studies have been done into the effectiveness of this approach. One of these studies compared the size (in lines of code) and speed of programs written by a seasoned programmer not familiar with the language and corrections to these programs by a Go expert (from Google's development team), doing the same for
Chapel A chapel is a Christian place of prayer and worship that is usually relatively small. The term has several meanings. Firstly, smaller spaces inside a church that have their own altar are often called chapels; the Lady chapel is a common type ...
, Cilk and Intel TBB. The study found that the non-expert tended to write divide-and-conquer algorithms with one statement per recursion, while the expert wrote distribute-work-synchronize programs using one goroutine per processor. The expert's programs were usually faster, but also longer.


Lack of race condition for safety

Go's approach to concurrency can be summarized as "don't communicate by sharing memory; share memory by communicating". There are no restrictions on how go-routines access shared data, making
race condition A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is Sequential logic, dependent on the sequence or timing of other uncontrollable events. It becomes a software ...
s possible. Specifically, unless a program explicitly synchronizes via channels or other means, writes from one go-routine might be partly, entirely, or not at all visible to another, often with no guarantees about ordering of writes. Furthermore, Go's ''internal data structures'' like interface values, slice headers, hash tables, and string headers are not immune to race conditions, so type and memory safety can be violated in multithreaded programs that modify shared instances of those types without synchronization. "There is one important caveat: Go is not purely memory safe in the presence of concurrency." Instead of language support, safe concurrent programming thus relies on conventions; for example, Chisnall recommends an idiom called "aliases
xor Exclusive or or exclusive disjunction is a logical operation that is true if and only if its arguments differ (one is true, the other is false). It is symbolized by the prefix operator J and by the infix operators XOR ( or ), EOR, EXOR, , ...
mutable", meaning that passing a mutable value (or pointer) over a channel signals a transfer of ownership over the value to its receiver.


Binaries

The linker in the gc toolchain creates statically linked binaries by default; therefore all Go binaries include the Go runtime.


Omissions

Go deliberately omits certain features common in other languages, including (implementation) inheritance, assertions, pointer arithmetic, implicit type conversions, untagged unions, and tagged unions. The designers added only those facilities that all three agreed on. Of the omitted language features, the designers explicitly argue against assertions and pointer arithmetic, while defending the choice to omit type inheritance as giving a more useful language, encouraging instead the use of
interfaces Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...
to achieve dynamic dispatch and composition to reuse code. Composition and
delegation Delegation is the assignment of authority to another person (normally from a manager to a subordinate) to carry out specific activities. It is the process of distributing and entrusting work to another person,Schermerhorn, J., Davidson, P., Poole ...
are in fact largely automated by embedding; according to researchers Schmager ''et al.'', this feature "has many of the drawbacks of inheritance: it affects the public interface of objects, it is not fine-grained (i.e, no method-level control over embedding), methods of embedded objects cannot be hidden, and it is static", making it "not obvious" whether programmers will overuse it to the extent that programmers in other languages are reputed to overuse inheritance.
Exception handling In computing and computer programming, exception handling is the process of responding to the occurrence of ''exceptions'' – anomalous or exceptional conditions requiring special processing – during the execution of a program. In general, an ...
was initially omitted in Go due to lack of a "design that gives value proportionate to the complexity". An exception-like / mechanism that avoids the usual try-catch control structure was proposed and released in the March 30, 2010 snapshot. The Go authors advise using it for unrecoverable errors such as those that should halt an entire program or server request, or as a shortcut to propagate errors up the stack within a package. Across package boundaries, Go includes a canonical error type, and multi-value returns using this type are the standard idiom.


Style

The Go authors put substantial effort into influencing the style of Go programs: * Indentation, spacing, and other surface-level details of code are automatically standardized by the gofmt tool. It uses tabs for indentation and blanks for alignment. Alignment assumes that an editor is using a fixed-width font. golint does additional style checks automatically, but has been deprecated and archived by the Go maintainers. * Tools and libraries distributed with Go suggest standard approaches to things like API documentation (godoc), testing (go test), building (go build), package management (go get), and so on. * Go enforces rules that are recommendations in other languages, for example banning cyclic dependencies, unused variables or imports, and implicit type conversions. * The ''omission'' of certain features (for example, functional-programming shortcuts like map and Java-style try/finally blocks) tends to encourage a particular explicit, concrete, and imperative programming style. * On day one the Go team published a collection of Go idioms, and later also collected code review comments, talks, and official blog posts to teach Go style and coding philosophy.


Tools

The main Go distribution includes tools for
building A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and func ...
,
testing An examination (exam or evaluation) or test is an educational assessment intended to measure a test-taker's knowledge, skill, aptitude, physical fitness, or classification in many other topics (e.g., beliefs). A test may be administered verba ...
, and analyzing code: * go build, which builds Go binaries using only information in the source files themselves, no separate makefiles * go test, for unit testing and microbenchmarks * go fmt, for formatting code * go install, for retrieving and installing remote packages * go vet, a static analyzer looking for potential errors in code * go run, a shortcut for building and executing code * godoc, for displaying documentation or serving it via HTTP * gorename, for renaming variables, functions, and so on in a type-safe way * go generate, a standard way to invoke code generators * go mod, for creating a new module, adding dependencies, upgrading dependencies, etc. It also includes profiling and
debugging In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve i ...
support, runtime instrumentation (for example, to track
garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of treatment or landfill. Waste collection also includes the curbside collection of recyclabl ...
pauses), and a
race condition A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is Sequential logic, dependent on the sequence or timing of other uncontrollable events. It becomes a software ...
tester. An ecosystem of third-party tools adds to the standard distribution, such as gocode, which enables code autocompletion in many text editors, goimports, which automatically adds/removes package imports as needed, and errcheck, which detects code that might unintentionally ignore errors.


Examples


Hello world

package main import "fmt" func main() where "fmt" is the package for ''formatted I/O'', similar to C's C file input/output.


Concurrency

The following simple program demonstrates Go's concurrency features to implement an asynchronous program. It launches two lightweight threads ("goroutines"): one waits for the user to type some text, while the other implements a timeout. The statement waits for either of these goroutines to send a message to the main routine, and acts on the first message to arrive (example adapted from David Chisnall's book). package main import ( "fmt" "time" ) func readword(ch chan string) func timeout(t chan bool) func main()


Testing

The testing package provides support for automated testing of go packages. Target function example: func ExtractUsername(email string) string Test code (note that assert keyword is missing in Go; tests live in _test.go at the same package): import ( "testing" ) func TestExtractUsername(t *testing.T) It is possible to run tests in parallel.


Web App

The net/http package provides support for creating web applications. This example would show "Hello world!" when localhost:8080 is visited. package main import ( "fmt" "log" "net/http" ) func helloFunc(w http.ResponseWriter, r *http.Request) func main()


Applications

Some notable
open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized so ...
applications written in Go include: * Caddy, an open source HTTP/2 web server with automatic HTTPS capability * CockroachDB, an open source, survivable, strongly consistent, scale-out SQL database *
Consul Consul (abbrev. ''cos.''; Latin plural ''consules'') was the title of one of the two chief magistrates of the Roman Republic, and subsequently also an important title under the Roman Empire. The title was used in other European city-states throu ...
, a software for DNS-based service discovery and providing distributed Key-value storage, segmentation and configuration. * Docker, a set of tools for deploying
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...
containers * EdgeX, a vendor-neutral open-source platform hosted by the
Linux Foundation The Linux Foundation (LF) is a non-profit technology consortium founded in 2000 as a merger between Open Source Development Labs and the Free Standards Group to standardize Linux, support its growth, and promote its commercial adoption. Addi ...
, providing a common framework for industrial IoT edge computing * Hugo, a static site generator *
InfluxDB InfluxDB is an open-source time series database (TSDB) developed by the company InfluxData. It is written in the Go programming language for storage and retrieval of time series data in fields such as operations monitoring, application metr ...
, an open source database specifically to handle time series data with high availability and high performance requirements * InterPlanetary File System, a content-addressable, peer-to-peer hypermedia protocol * Juju, a service orchestration tool by Canonical, packagers of
Ubuntu Ubuntu ( ) is a Linux distribution based on Debian and composed mostly of free and open-source software. Ubuntu is officially released in three editions: '' Desktop'', ''Server'', and ''Core'' for Internet of things devices and robots. All ...
Linux * Kubernetes container management system * lnd, an implementation of the
Bitcoin Bitcoin (abbreviation: BTC; sign: ₿) is a decentralized digital currency that can be transferred on the peer-to-peer bitcoin network. Bitcoin transactions are verified by network nodes through cryptography and recorded in a public distr ...
Lightning Network The Lightning Network (LN) is a "layer 2" payment protocol layered on top of Bitcoin (and other blockchains and cryptocurrencies). It is intended to enable fast transactions among participating nodes and has been proposed as a solution to the ...
* Mattermost, a teamchat system * NATS Messaging, an open-source messaging system featuring the core design principles of performance, scalability, and ease of use *
OpenShift OpenShift is a family of containerization software products developed by Red Hat. Its flagship product is the OpenShift Container Platform — a hybrid cloud platform as a service built around Linux containers orchestrated and managed by Kuber ...
, a cloud computing platform as a service by
Red Hat Red Hat, Inc. is an American software company that provides open source software products to enterprises. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina, with other offices worldwide. Red Hat has become a ...
* Rclone, a command line program to manage files on cloud storage and other high latency services * Snappy, a package manager for Ubuntu Touch developed by Canonical *
Syncthing Syncthing is a free, open-source peer-to-peer file synchronization application available for Windows, macOS, Linux, Android, Solaris, Darwin, and BSD. It can sync files between devices on a local network, or between remote devices over the Intern ...
, an open-source file synchronization client/server application * Terraform, an open-source, multiple
cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...
infrastructure provisioning tool from HashiCorp * TiDB, an open-source, distributed
HTAP Hybrid transaction/analytical processing (HTAP) is a term created by Gartner Inc., an information technology research and advisory company, in its early 2014 research report ''Hybrid Transaction/Analytical Processing Will Foster Opportunities for ...
database compatible with the MySQL protocol from PingCAP * Vitess, an open-source, distributed MySQL compatible database out of
YouTube YouTube is a global online video sharing and social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the second mo ...
that is now hosted by the
Cloud Native Computing Foundation The Cloud Native Computing Foundation (CNCF) is a Linux Foundation project that was founded in 2015 to help advance container technology and align the tech industry around its evolution. It was announced alongside Kubernetes 1.0, an open sourc ...
* arctil, Web security assessment tool Other notable companies and sites using Go (generally together with other languages, not exclusively) include: * Cacoo, for their rendering of the user dashboard page and microservice using Go and gRPC * Chango, a programmatic advertising company uses Go in its real-time bidding systems * Cloud Foundry, a
platform as a service Platform as a service (PaaS) or application platform as a service (aPaaS) or platform-based service is a category of cloud computing services that allows customers to provision, instantiate, run, and manage a modular bundle comprising a computing ...
* Cloudflare, for their delta-coding proxy Railgun, their distributed DNS service, as well as tools for cryptography, logging, stream processing, and accessing SPDY sites *
Container Linux Container Linux (formerly CoreOS Linux) is a discontinued open-source lightweight operating system based on the Linux kernel and designed for providing infrastructure to clustered deployments, while focusing on automation, ease of applicatio ...
(formerly CoreOS), a Linux-based operating system that uses Docker containers and rkt containers * Couchbase, Query and Indexing services within the Couchbase Server * Dropbox, who migrated some of their critical components from Python to Go * Ethereum, The ''go-ethereum'' implementation of the Ethereum Virtual Machine blockchain for the ''Ether'' cryptocurrency *
GitLab GitLab Inc. is an open-core company that operates GitLab, a DevOps software package which can develop, secure, and operate software. The open source software project was created by Ukrainian developer Dmitriy Zaporozhets and Dutch developer ...
, a web-based DevOps lifecycle tool that provides a
Git Git () is a distributed version control system: tracking changes in any set of files, usually used for coordinating work among programmers collaboratively developing source code during software development. Its goals include speed, data in ...
- repository,
wiki A wiki ( ) is an online hypertext publication collaboratively edited and managed by its own audience, using a web browser. A typical wiki contains multiple pages for the subjects or scope of the project, and could be either open to the pub ...
, issue-tracking, continuous integration, deployment pipeline features *
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
, for many projects, notably including download server dl.google.com *
Heroku Heroku is a cloud platform as a service (PaaS) supporting several programming languages. One of the first cloud platforms, Heroku has been in development since June 2007, when it supported only the Ruby programming language, but now supports Jav ...
, for Doozer, a lock service * Hyperledger Fabric, an open source, enterprise-focused distributed ledger project *
MongoDB MongoDB is a source-available cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas. MongoDB is developed by MongoDB Inc. and licensed under the S ...
, tools for administering MongoDB instances *
Netflix Netflix, Inc. is an American subscription video on-demand over-the-top streaming service and production company based in Los Gatos, California. Founded in 1997 by Reed Hastings and Marc Randolph in Scotts Valley, California, it offers a ...
, for two portions of their server architecture * Nutanix, for a variety of micro-services in its Enterprise Cloud OS * Plug.dj, an interactive online social music streaming website * SendGrid, a Boulder, Colorado-based transactional email delivery and management service. *
SoundCloud SoundCloud is an online audio distribution platform and music sharing website that enables its users to upload, promote, and share audio. Founded in 2007 by Alexander Ljung and Eric Wahlforss, SoundCloud is one of the largest music streaming se ...
, for "dozens of systems" * Splice, for the entire backend (API and parsers) of their online music collaboration platform * ThoughtWorks, some tools and applications for
continuous delivery Continuous delivery (CD) is a software engineering approach in which teams produce software in short cycles, ensuring that the software can be reliably released at any time and, following a pipeline through a "production-like environment", witho ...
and instant messages (CoyIM) * Twitch, for their IRC-based chat system (migrated from Python) *
Uber Uber Technologies, Inc. (Uber), based in San Francisco, provides mobility as a service, ride-hailing (allowing users to book a car and driver to transport them in a way similar to a taxi), food delivery ( Uber Eats and Postmates), pa ...
, for handling high volumes of geofence-based queries See als
related query to Wikidata


Reception

The interface system, and the deliberate omission of inheritance, were praised by Michele Simionato, who likened these characteristics to those of
Standard ML Standard ML (SML) is a general-purpose, modular, functional programming language with compile-time type checking and type inference. It is popular among compiler writers and programming language researchers, as well as in the development of ...
, calling it "a shame that no popular language has followed hisparticular route". Dave Astels at Engine Yard wrote in 2009: Go was named Programming Language of the Year by the TIOBE Programming Community Index in its first year, 2009, for having a larger 12-month increase in popularity (in only 2 months, after its introduction in November) than any other language that year, and reached 13th place by January 2010, surpassing established languages like
Pascal Pascal, Pascal's or PASCAL may refer to: People and fictional characters * Pascal (given name), including a list of people with the name * Pascal (surname), including a list of people and fictional characters with the name ** Blaise Pascal, Frenc ...
. By June 2015, its ranking had dropped to below 50th in the index, placing it lower than
COBOL COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural and, since 2002, object-oriented language. COBOL is primarily u ...
and Fortran. But as of January 2017, its ranking had surged to 13th, indicating significant growth in popularity and adoption. Go was awarded TIOBE programming language of the year 2016. Bruce Eckel has stated: A 2011 evaluation of the language and its implementation in comparison to C++ ( GCC), Java and Scala by a Google engineer found: The evaluation got a rebuttal from the Go development team. Ian Lance Taylor, who had improved the Go code for Hundt's paper, had not been aware of the intention to publish his code, and says that his version was "never intended to be an example of idiomatic or efficient Go"; Russ Cox then optimized the Go code, as well as the C++ code, and got the Go code to run slightly faster than C++ and more than an order of magnitude faster than the code in the paper.


Naming dispute

On November 10, 2009, the day of the general release of the language, Francis McCabe, developer of the Go! programming language (note the exclamation point), requested a name change of Google's language to prevent confusion with his language, which he had spent 10 years developing. McCabe raised concerns that "the 'big guy' will end up steam-rollering over" him, and this concern resonated with the more than 120 developers who commented on Google's official issues thread saying they should change the name, with some even saying the issue contradicts Google's motto of:
Don't be evil "Don't be evil" is a phrase that was used in Google's corporate code of conduct, which it also formerly preceded as a motto. Following Google's corporate restructuring under the conglomerate Alphabet Inc. in October 2015, Alphabet took "Do the r ...
. On October 12, 2010, the issue was closed by Google developer Russ Cox (@rsc) with the custom status "Unfortunate" accompanied by the following comment:
"There are many computing products and services named Go. In the 11 months since our release, there has been minimal confusion of the two languages."


Criticism

* Go's '' nil'' combined with the lack of algebraic types leads to difficulty handling failures and base cases. * Go does not allow an opening brace to appear on its own line, which forces all Go programmers to use the same brace style. * File semantics in Go standard library are heavily based on
POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming in ...
semantics, and they do not map well to the Windows platform. Note that this problem is not particular to Go, but other programming languages have solved it through well defined standard libraries. * A study showed that it is as easy to make concurrency bugs with message passing as with shared memory, sometimes even more.


See also

* Fat pointer * Comparison of programming languages


Notes


References


Further reading

* *


External links

* {{Authority control 2009 software American inventions C programming language family Concurrent programming languages Cross-platform free software Cross-platform software Free compilers and interpreters Google software High-level programming languages Procedural programming languages Programming languages Programming languages created in 2009 Software using the BSD license Statically typed programming languages Systems programming languages