Nim (programming language)
Nim is a general-purpose, multi-paradigm, statically typed, compiled high-level systems programming language,[9] designed and developed by a team around Andreas Rumpf. Nim is designed to be "efficient, expressive, and elegant",[10] supporting metaprogramming, functional, message passing,[11] procedural, and object-oriented programming styles by providing several features such as compile time code generation, algebraic data types, a foreign function interface (FFI) with C, C++, Objective-C, and JavaScript, and supporting compiling to those same languages as intermediate representations.
Paradigms | Multi-paradigm: compiled, concurrent, procedural, imperative, functional, object-oriented, meta |
---|---|
Designed by | Andreas Rumpf |
Developer | Nim Lang Team[1] |
First appeared | 2008 |
Stable release | 2.0.0[2]
/ 1 August 2023 |
Typing discipline | Static,[3] strong,[4] inferred, structural |
Scope | Lexical |
Implementation language | Nim (self-hosted) |
Platform | IA-32, x86-64, ARM, Aarch64, RISC-V, PowerPC ...[5] |
OS | Cross-platform[6] |
License | MIT license[7] |
Filename extensions | .nim, .nims, .nimble |
Website | nim-lang |
Influenced by | |
Ada, Modula-3, Lisp, C++, Object Pascal, Python, Oberon, Rust, ParaSail[8] |
Description
Nim is statically typed.[12] It supports compile-time metaprogramming features such as syntactic macros and term rewriting macros.[13] Term rewriting macros enable library implementations of common data structures, such as bignums and matrices, to be implemented efficiently and with syntactic integration, as if they were built-in language facilities.[14] Iterators are supported and can be used as first class entities,[13] as can functions, allowing for the use of functional programming methods. Object-oriented programming is supported by inheritance and multiple dispatch. Functions can be generic and overloaded, and generics are further enhanced by Nim's support for type classes. Operator overloading is also supported.[13] Nim includes multiple tunable memory management strategies, including tracing garbage collection, reference counting, and fully manual systems, with the default being deterministic reference counting with optimizations via move semantics and cycle collection via trial deletion.[15]
[Nim] ... presents a most original design that straddles Pascal and Python and compiles to C code or JavaScript.[16]
— Andrew Binstock, editor-in-chief of Dr. Dobb's Journal, 2014
As of August 2023, Nim compiles to C, C++, JavaScript, Objective-C,[17] and LLVM.[18]
History
Branch | Version | Release date[19] |
---|---|---|
0.x | 0.10.2 | 2014-12-29 |
0.11.2 | 2015-05-04 | |
0.12.0 | 2015-10-27 | |
0.13.0 | 2016-01-18 | |
0.14.2 | 2016-06-09 | |
0.15.2 | 2016-10-23 | |
0.16.0 | 2017-01-08 | |
0.17.2 | 2017-09-07 | |
0.18.0 | 2018-03-01 | |
0.19.6 | 2019-05-13 | |
0.20.2 | 2019-06-17 | |
1.0 | 1.0.0 | 2019-09-23 |
1.0.10 | 2020-10-27 | |
1.2 | 1.2.0 | 2020-04-03 |
1.2.18 | 2022-02-09 | |
1.4 | 1.4.0 | 2020-10-16 |
1.4.8 | 2021-05-25 | |
1.6 | 1.6.0 | 2021-10-19 |
1.6.16 | 2023-10-11 | |
2.0 | 2.0.0 | 2023-08-01 |
Legend: Old version Older version, still maintained Latest version | ||
For each 0.x branch, only the latest point release is listed. For later branches, the first and the latest point release is listed. |
According to language creator, nim was conceived to combine best parts of Ada typing system, Python flexibility, and powerful Lisp macro system.[20]
Nim's initial development was started in 2005 by Andreas Rumpf. It was originally named Nimrod when the project was made public in 2008.[21]: 4–11
The first version of the Nim compiler was written in Pascal using the Free Pascal compiler.[22] In 2008, a version of the compiler written in Nim was released.[23] The compiler is free and open-source software, and is being developed by a community of volunteers working with Andreas Rumpf.[24] The language was officially renamed from Nimrod to Nim with the release of version 0.10.2 in December 2014.[25] On September 23, 2019, version 1.0 of Nim was released, signifying the maturing of the language and its toolchain. On August 1st, 2023, version 2.0 of Nim was released, signifying the completion, stabilization of, and switch to the ARC/ORC memory model.[26]
Language design
Syntax
The syntax of Nim resembles that of Python.[27] Code blocks and nesting statements are identified through use of whitespace, according to the offside-rule. Many keywords are identical to their Python equivalents, which are mostly English keywords, whereas other programming languages usually use punctuation. With the goal of improving upon its influence languages, even though Nim supports indentation-based syntax like Python, it introduced additional flexibility. For example, a single statement may span multiple lines if a comma or binary operator is at the end of each line. Nim also supports user-defined operators.
Unlike Python, Nim implements (native) static typing. Nim's type system allows for easy type conversion, casting, and provides syntax for generic programming. Nim notably provides type classes which can stand in for multiple types, and provides several such type classes 'out of the box'. Type classes allow working with several types as if they were a single type. For example:
openarray
– Represents arrays of different sizes, sequences, and stringsSomeSignedInt
– Represents all the signed integer typesSomeInteger
– Represents all the Integer types, signed or notSomeOrdinal
– Represents all the basic countable and ordered types, except of non integer number
This code sample demonstrates the use of typeclasses in Nim
# Let's declare a function that takes any type of number and displays its double
# In Nim functions with side effect are called "proc"
proc timesTwo(i: SomeNumber) =
echo i * 2
# Let's write another function that takes any ordinal type, and returns
# the double of the input in its original type, if it is a number;
# or returns the input itself otherwise.
# We use a generic Type(T), and precise that it can only be an Ordinal
func twiceIfIsNumber[T: SomeOrdinal](i: T): T =
when T is SomeNumber: # A `when` is an `if` evaluated during compile time
result = i * 2 # You can also write `return i * 2`
else:
# If the Ordinal is not a number it is converted to int,
# multiplied by two, and reconverted to its based type
result = (i.int * 2).T
echo twiceIfIsNumber(67) # Passes an int to the function
echo twiceIfIsNumber(67u8) # Passes an uint8
echo twiceIfIsNumber(true) # Passes a bool (Which is also an Ordinal)
Influence
Nim was influenced by specific characteristics of existing languages, including the following:
- Modula-3: traced vs untraced pointers
- Object Pascal: type safe bit sets (set of char), case statement syntax, various type names and filenames in the standard library
- Ada: subrange types, distinct type, safe variants – case objects
- C++: operator overloading, generic programming
- Python: Off-side rule
- Lisp: Macro system, AST manipulation, homoiconicity
- Oberon: export marker
- C#: async/await, lambda macros
- ParaSail: pointer-free programming[8]
Uniform Function Call Syntax
Nim supports Uniform Function Call Syntax (UFCS)[28] and identifier equality, which provides a large degree of flexibility in use.
For example, each of these lines print "hello world", just with different syntax:
echo "hello world"
echo("hello world")
"hello world".echo()
"hello world".echo
echo("hello", " world")
"hello".echo(" world")
"hello".echo " world"
Identifier equality
Nim is almost fully style-insensitive; two identifiers are considered equal if they only differ by capitalization and underscores, as long as the first characters are identical. This is to enable a mixture of styles across libraries: one user can write a library using snake_case as a convention, and it can be used by a different user in a camelCase style without issue.[29]
const useHttps = true
assert useHttps == useHttps
assert useHTTPS == useHttps
assert use_https == useHttps
Stropping
The stropping feature allows the use of any name for variables or functions, even when the names are reserved words for keywords. An example of stropping is the ability to define a variable named if
, without clashing with the keyword if
. Nim's implementation of this is achieved via backticks, allowing any reserved word to be used as an identifier.[30]
type Type = object
`int`: int
let `object` = Type(`int`: 9)
assert `object` is Type
assert `object`.`int` == 9
var `var` = 42
let `let` = 8
assert `var` + `let` == 50
const `assert` = true
assert `assert`
Compiler
The Nim compiler emits fast, optimized C code by default. It defers compiling-to-object code to an external C compiler[31] to leverage existing compiler optimization and portability. Many C compilers are supported, including Clang, Microsoft Visual C++ (MSVC), MinGW, and GNU Compiler Collection (GCC). The Nim compiler can also emit C++, Objective-C, and JavaScript code to allow easy interfacing with application programming interfaces (APIs) written in those languages;[9] developers can simply write in Nim, then compile to any supported language. This also allows writing applications for iOS and Android. There is also an unofficial LLVM backend, allowing use of the Nim compiler in a stand-alone way.[18]
The Nim compiler is self-hosting, meaning it is written in the Nim language.[32] The compiler supports cross-compiling, so it is able to compile software for any of the supported operating systems, no matter the development machine. This is useful for compiling applications for embedded systems, and for uncommon and obscure computer architectures.
Compiler options
By default, the Nim compiler creates a debug build.[33]
With the option -d:release
a release build can be created, which is optimized for speed and contains fewer runtime checks.[33]
With the option -d:danger
all runtime checks can be disabled, if maximum speed is desired.[33]
Memory management
Nim supports multiple memory management strategies, including the following:[34]
--gc:refc
– Standard deferred reference counting based garbage collector with a simple mark-and-sweep backup GC in order to collect cycles. Heaps are thread-local.--gc:markAndSweep
– Simple mark-and-sweep based garbage collector. Heaps are thread-local.--gc:boehm
– Boehm based garbage collector, it offers a shared heap.--gc:go
– Go's garbage collector, useful for interoperability with Go. Offers a shared heap.--gc:arc
– Automatic reference counting (ARC) with move semantics optimizations, offers a shared heap. It offers fully deterministic performance for hard realtime systems.[35] Reference cycles may cause memory leaks: these may be dealt with by manually annotating{.acyclic.}
pragmas or by using--gc:orc
.--gc:orc
– Same as--gc:arc
but adds a cycle collector (the "O") based on "trial deletion".[36] The cycle collector only analyzes types if they are potentially cyclic.--gc:none
– No memory management strategy nor a garbage collector. Allocated memory is simply never freed, unless manually freed by the developer's code.
As of Nim 2.0, ORC is the default GC.[37]
Development tools
Bundled
Many tools are bundled with the Nim install package, including:
Nimble
Nimble is the standard package manager used by Nim to package Nim modules.[38] It was initially developed by Dominik Picheta, who is also a core Nim developer. Nimble has been included as Nim's official package manager since Oct 27, 2015, the v0.12.0 release.[39]
Nimble packages are defined by .nimble
files, which contain information about the package version, author, license, description, dependencies, and more.[21]: 132 These files support a limited subset of the Nim syntax called NimScript, with the main limitation being the access to the FFI. These scripts allow changing of test procedure, or for custom tasks to be written.
The list of packages is stored in a JavaScript Object Notation (JSON) file which is freely accessible in the nim-lang/packages repository on GitHub. This JSON file provides Nimble with a mapping between the names of packages and their Git or Mercurial repository URLs.
Nimble comes with the Nim compiler. Thus, it is possible to test the Nimble environment by running:
nimble -v
.
This command will reveal the version number, compiling date and time, and Git hash of nimble. Nimble uses the Git package, which must be available for Nimble to function properly. The Nimble command-line is used as an interface for installing, removing (uninstalling), and upgrading–patching module packages.[21]: 130–131
c2nim
c2nim is a source-to-source compiler (transcompiler or transpiler) meant to be used on C/C++ headers to help generate new Nim bindings.[40] The output is human-readable Nim code that is meant to be edited by hand after the translation process.
koch
koch is a maintenance script that is used to build Nim, and provide HTML documentation.[41]
nimgrep
nimgrep is a generic tool for manipulating text. It is used to search for regex, peg patterns, and contents of directories, and it can be used to replace tasks. It is included to assist with searching Nim's style-insensitive identifiers.[42]
nimsuggest
nimsuggest is a tool that helps any source code editor query a .nim
source file to obtain useful information like definition of symbols or suggestions for completions.[43]
niminst
niminst is a tool to generate an installer for a Nim program.[44] It creates .msi installers for Windows via Inno Setup, and install and uninstall scripts for Linux, macOS, and Berkeley Software Distribution (BSD).
nimpretty
nimpretty is a source code beautifier, used to format code according to the official Nim style guide.[45]
Testament
Testament is an advanced automatic unit tests runner for Nim tests. Used in developing Nim, it offers process isolation tests, generates statistics about test cases, supports multiple targets and simulated Dry-Runs, has logging, can generate HTML reports, can skip tests from a file, and more.
Other notable tools
Some notable tools not included in the Nim distribution include:
Libraries
Pure/impure libraries
Pure libraries are modules written in Nim only. They include no wrappers to access libraries written in other programming languages.
Impure libraries are modules of Nim code which depend on external libraries that are written in other programming languages such as C.
Standard library
The Nim standard library includes modules for all basic tasks, including:[49]
- System and core modules
- Collections and algorithms
- String handling
- Time handling
- Generic Operating System Services
- Math libraries
- Internet Protocols and Support
- Threading
- Parsers
- Docutils
- XML Processing
- XML and HTML code generator
- Hashing
- Database support (PostgreSQL, MySQL and SQLite)
- Wrappers (Win32 API, POSIX)
Use of other libraries
A Nim program can use any library which can be used in a C, C++, or JavaScript program. Language bindings exist for many libraries, including GTK,[50][51] Qt QML,[52] wxWidgets,[53] SDL 2,[54][55] Cairo,[56] OpenGL,[57] WinAPI,[58] zlib, libzip, OpenSSL, Vulkan[59] and cURL.[60] Nim works with PostgreSQL, MySQL, and SQLite databases.
There are open source tools of various degree of support that can be used to interface nvim with Lua,[61] Julia,[62] Rust,[63] C#,[64] and Python[65] programming languages or transpile nvim to TypeScript.[66]
Examples
Hello world
The "Hello, World!" program in Nim:
echo("Hello, World!")
# Procedures can be called with no parentheses
echo "Hello, World!"
Another version of "Hello World" can be accomplished by calling the write
function with the stdout
stream:
stdout.write("Hello, World!\n")
write(stdout, "Hello, World!\n")
Fibonacci
Several implementations of the Fibonacci function, showcasing implicit returns, default parameters, iterators, recursion, and while loops:
proc fib(n: Natural): Natural =
if n < 2:
return n
else:
return fib(n-1) + fib(n-2)
func fib2(n: int, a = 0, b = 1): int =
if n == 0: a else: fib2(n-1, b, a+b)
iterator fib3: int =
var a = 0
var b = 1
while true:
yield a
swap a, b
b += a
Factorial
Program to calculate the factorial of a positive integer using the iterative approach, showcasing try/catch error handling and for loops:
import std/strutils
var n = 0
try:
stdout.write "Input positive integer number: "
n = stdin.readline.parseInt
except ValueError:
raise newException(ValueError, "You must enter a positive number")
var fact = 1
for i in 2..n:
fact = fact * i
echo fact
Using the module math from Nim's standard library:
import std/math
echo fac(x)
Reversing a string
A simple demonstration showing the implicit result variable and the use of iterators.
proc reverse(s: string): string =
for i in countdown(s.high, 0):
result.add s[i]
let str1 = "Reverse This!"
echo "Reversed: ", reverse(str1)
One of Nim's more exotic features is the implicit result
variable. Every procedure in Nim with a non-void return type has an implicit result variable that represents the value to be returned. In the for loop we see an invocation of countdown
which is an iterator. If an iterator is omitted, the compiler will attempt to use an items
iterator, if one is defined for the type specified.
Graphical user interface
Using GTK 3 with GObject introspection through the gintro module:
import gintro/[gtk, glib, gobject, gio]
proc appActivate(app: Application) =
let window = newApplicationWindow(app)
window.title = "GTK3 application with gobject introspection"
window.defaultSize = (400, 400)
showAll(window)
proc main =
let app = newApplication("org.gtk.example")
connect(app, "activate", appActivate)
discard run(app)
main()
This code requires the gintro module to work, which is not part of the standard library. To install the module gintro and many others you can use the tool nimble, which comes as part of Nim. To install the gintro module with nimble you do the following:
nimble install gintro
Programming paradigms
Functional programming
Functional programming is supported in Nim through first-class functions and code without side effects via the noSideEffect
pragma or the func
keyword.[67] Nim will perform side effect analysis and raise compilation errors for code that does not obey the contract of producing no side effects when compiled with the experimental feature strictFuncs
, planned to become the default in later versions.[68]
Contrary to purely functional programming languages, Nim is a multi-paradigm programming language, so functional programming restrictions are opt-in on a function-by-function basis.
First-class functions
Nim supports first-class functions by allowing functions to be stored in variables or passed anonymously as parameters to be invoked by other functions.[69] The std/sugar
module provides syntactic sugar for anonymous functions in type declarations and instantiation.
import std/[sequtils, sugar]
let powersOfTwo = @[1, 2, 4, 8, 16, 32, 64, 128, 256]
proc filter[T](s: openArray[T], pred: T -> bool): seq[T] =
result = newSeq[T]()
for i in 0 ..< s.len:
if pred(s[i]):
result.add(s[i])
echo powersOfTwo.filter(proc (x: int): bool = x > 32)
# syntactic sugar for the above, provided as a macro from std/sugar
echo powersOfTwo.filter(x => x > 32)
proc greaterThan32(x: int): bool = x > 32
echo powersOfTwo.filter(greaterThan32)
Side effects
Side effects of functions annotated with the noSideEffect
pragma are checked, and the compiler will refuse to compile functions failing to meet those. Side effects in Nim include mutation, global state access or modification, asynchronous code, threaded code, and IO. Mutation of parameters may occur for functions taking parameters of var
or ref
type: this is expected to fail to compile with the currently-experimental strictFuncs
in the future.[70] The func
keyword introduces a shortcut for a noSideEffect
pragma.[71]
func binarySearch[T](a: openArray[T]; elem: T): int
# is short for...
proc binarySearch[T](a: openArray[T]; elem: T): int {.noSideEffect.}
{.experimental: "strictFuncs".}
type
Node = ref object
le, ri: Node
data: string
func len(n: Node): int =
# valid: len does not have side effects
var it = n
while it != nil:
inc result
it = it.ri
func mut(n: Node) =
let m = n # is the statement that connected the mutation to the parameter
m.data = "yeah" # the mutation is here
# Error: 'mut' can have side effects
# an object reachable from 'n' is potentially mutated
Function composition
Uniform function call syntax allows for the chaining of arbitrary functions, perhaps best exemplified with the std/sequtils
library.[72]
import std/[sequtils, sugar]
let numbers = @[1, 2, 3, 4, 5, 6, 7, 8, 7, 6, 5, 4, 3, 2, 1]
# a and b are special identifiers in the foldr macro
echo numbers.filter(x => x > 3).deduplicate.foldr(a + b) # 30
Algebraic data types and pattern matching
Nim has support for product types via the object
type, and for sum types via object variants: raw representations of tagged unions, with an enumerated type tag that must be safely matched upon before fields of variants can be accessed.[73] These types can be composed algebraically. Structural pattern matching is available, but regulated to macros in various third-party libraries.[74]
import std/tables
type
Value = uint64
Ident = string
ExprKind = enum
Literal, Variable, Abstraction, Application
Expr = ref object
case kind: ExprKind
of Literal:
litIdent: Value
of Variable:
varIdent: Ident
of Abstraction:
paramAbs: Ident
funcAbs: Expr
of Application:
funcApp, argApp: Expr
func eval(expr: Expr, context: var Table[Ident, Value]): Value =
case expr.kind
of Literal:
return expr.litIdent
of Variable:
return context[expr.varIdent]
of Application:
case expr.funcApp.kind
of Abstraction:
context[expr.funcApp.paramAbs] = expr.argApp.eval(context)
return expr.funcAbs.eval(context)
else:
raise newException(ValueError, "Invalid expression!")
else:
raise newException(ValueError, "Invalid expression!")
Object-oriented programming
Despite being primarily an imperative and functional language, Nim supports various features for enabling object-oriented paradigms.[75][76]
Subtyping and inheritance
Nim supports limited inheritance by use of ref objects
and the of
keyword.[76] To enable inheritance, any initial ("root") object must inherit from RootObj
. Inheritance is of limited use within idiomatic Nim code: with the notable exception of Exceptions.[77]
type Animal = ref object of RootObj
name: string
age: int
type Dog = ref object of Animal
type Cat = ref object of Animal
var animals: seq[Animal] = @[]
animals.add(Dog(name: "Sparky", age: 10))
animals.add(Cat(name: "Mitten", age: 10))
for a in animals:
assert a of Animal
Subtyping relations can also be queried with the of
keyword.[76]
Method calls and encapsulation
Nim's uniform function call syntax enables calling ordinary functions with syntax similar to method call invocations in other programming languages. This is functional for "getters": and Nim also provides syntax for the creation of such "setters" as well. Objects may be made public on a per-field basis, providing for encapsulation.
type Socket* = ref object
host: int # private, lacks export marker
# getter of host address
proc host*(s: Socket): int = s.host
# setter of host address
proc `host=`*(s: var Socket, value: int) =
s.host = value
var s: Socket
new s
assert s.host == 0 # same as host(s), s.host()
s.host = 34 # same as `host=`(s, 34)
Dynamic dispatch
Static dispatch is preferred, more performant, and standard even among method-looking routines.[76] Nonetheless, if dynamic dispatch is so desired, Nim provides the method
keyword for enabling dynamic dispatch on reference types.
import std/strformat
type
Person = ref object of RootObj
name: string
Student = ref object of Person
Teacher = ref object of Person
method introduce(a: Person) =
raise newException(CatchableError, "Method without implementation override")
method introduce(a: Student) =
echo &"I am a student named {a.name}!"
method introduce(a: Teacher) =
echo &"I am a teacher named {a.name}!"
let people: seq[Person] = @[Teacher(name: "Alice"), Student(name: "Bob")]
for person in people:
person.introduce()
Templates
Nim supports simple substitution on the abstract syntax tree via its templates.
template genType(name, fieldname: untyped, fieldtype: typedesc) =
type
name = object
fieldname: fieldtype
genType(Test, foo, int)
var x = Test(foo: 4566)
echo(x.foo) # 4566
The genType
is invoked at compile-time and a Test
type is created.
Generics
Nim supports both constrained and unconstrained generic programming.
Generics may be used in procedures, templates and macros. Unconstrained generic identifiers (T
in this example) are defined after the routine's name in square brackets. Constrained generics can be placed on generic identifiers, or directly on parameters.
proc addThese[T](a, b: T): T = a + b
echo addThese(1, 2) # 3 (of int type)
echo addThese(uint8 1, uint8 2) # 3 (of uint8 type)
# we don't want to risk subtracting unsigned numbers!
proc subtractThese[T: SomeSignedInt | float](a, b: T): T = a - b
echo subtractThese(1, 2) # -1 (of int type)
import std/sequtils
# constrained generics can also be directly on the parameters
proc compareThese[T](a, b: string | seq[T]): bool =
for (i, j) in zip(a, b):
if i != j:
return false
One can further clarify which types the procedure will accept by specifying a type class (in the example above, SomeSignedInt
).[78]
Macros
Macros can rewrite parts of the code at compile-time. Nim macros are powerful and can operate on the abstract syntax tree before or after semantic checking.[79]
Here's a simple example that creates a macro to call code twice:
import std/macros
macro twice(arg: untyped): untyped =
result = quote do:
`arg`
`arg`
twice echo "Hello world!"
The twice
macro in this example takes the echo statement in the form of an abstract syntax tree as input. In this example we decided to return this syntax tree without any manipulations applied to it. But we do it twice, hence the name of the macro. The result is that the code gets rewritten by the macro to look like the following code at compile time:
echo "Hello world!"
echo "Hello world!"
Foreign function interface (FFI)
Nim's FFI is used to call functions written in the other programming languages that it can compile to. This means that libraries written in C, C++, Objective-C, and JavaScript can be used in the Nim source code. One should be aware that both JavaScript and C, C++, or Objective-C libraries cannot be combined in the same program, as they are not as compatible with JavaScript as they are with each other. Both C++ and Objective-C are based on and compatible with C, but JavaScript is incompatible, as a dynamic, client-side web-based language.[21]: 226
The following program shows the ease with which external C code can be used directly in Nim.
proc printf(formatstr: cstring) {.header: "<stdio.h>", varargs.}
printf("%s %d\n", "foo", 5)
In this code the printf
function is imported into Nim and then used.
Basic example using 'console.log' directly for the JavaScript compilation target:
proc log(args: any) {.importjs: "console.log(@)", varargs.}
log(42, "z", true, 3.14)
The JavaScript code produced by the Nim compiler can be executed with Node.js or a web browser.
Parallelism
To activate threading support in Nim, a program should be compiled with --threads:on
command line argument. Each thread has a separate garbage collected heap and sharing of memory is restricted, which helps with efficiency and stops race conditions by the threads.
import std/locks
var
thr: array[0..4, Thread[tuple[a,b: int]]]
L: Lock
proc threadFunc(interval: tuple[a,b: int]) {.thread.} =
for i in interval.a..interval.b:
acquire(L) # lock stdout
echo i
release(L)
initLock(L)
for i in 0..high(thr):
createThread(thr[i], threadFunc, (i*10, i*10+5))
joinThreads(thr)
Nim also has a channels
module that simplifies passing data between threads.
import std/os
type
CalculationTask = object
id*: int
data*: int
CalculationResult = object
id*: int
result*: int
var task_queue: Channel[CalculationTask]
var result_queue: Channel[CalculationResult]
proc workerFunc() {.thread.} =
result_queue.open()
while true:
var task = task_queue.recv()
result_queue.send(CalculationResult(id: task.id, result: task.data * 2))
var workerThread: Thread[void]
createThread(workerThread, workerFunc)
task_queue.open()
task_queue.send(CalculationTask(id: 1, data: 13))
task_queue.send(CalculationTask(id: 2, data: 37))
while true:
echo "got result: ", repr(result_queue.recv())
Concurrency
Asynchronous IO is supported either via the asyncdispatch
module in the standard library or the external chronos
library.[80] Both libraries add async/await syntax via the macro system, without need for special language support. An example of an asynchronous HTTP server:
import std/[asynchttpserver, asyncdispatch]
# chronos could also be alternatively used in place of asyncdispatch,
# with no other changes.
var server = newAsyncHttpServer()
proc cb(req: Request) {.async.} =
await req.respond(Http200, "Hello World")
waitFor server.serve(Port(8080), cb)
Community
Online
Nim has an active community on the self-hosted, self-developed official forum.[81] Further, the project uses a Git repository, bug tracker, RFC tracker, and wiki hosted by GitHub, where the community engages with the language.[82] There are also official online chat rooms, bridged between IRC, Matrix, Discord, Gitter, and Telegram.[83]
Conventions
The first Nim conference, NimConf, took place on June 20, 2020. It was held digitally due to COVID-19, with an open call for contributor talks in the form of YouTube videos.[84] The conference began with language overviews by Nim developers Andreas Rumpf and Dominik Picheta. Presentation topics included talks about web frameworks, mobile development, Internet of things (IoT) devices, and game development, including a talk about writing Nim for Game Boy Advance.[85] NimConf 2020 is available as a YouTube playlist.[86] NimConf 2021 occurred the following year, was also held digitally, and included talks about game development, REPLs, real-time operating systems, Nim in the industry, object-relational mapping (ORM), language design, and graphics libraries.[87]
In addition to official conferences, Nim has been featured at various other conventions. A presentation on Nim was given at the O'Reilly Open Source Convention (OSCON) in 2015.[88][89][90] Four speakers represented Nim at FOSDEM 2020, including the creator of the language, Andreas Rumpf.[91] At FOSDEM 2022, Nim hosted their own developer room virtually due to the COVID-19 pandemic.[92] Talks were held on concurrency, embedded programming, programming for GPUs, entity-component systems, game development, rules engines, Python interop, and metaprogramming.[93]
See also
References
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External links
- Official website
- Nim on GitHub
- Information about Nim on Stack Overflow
- Computer Programming with the Nim Programming Language A gentle Introduction by Stefan Salewski