About Nim

The Nim Programming Language

Introduction

Nim is a statically-typed, high-level programming language that combines the performance of low-level languages like C and C++ with the expressiveness of high-level languages like Python, Lisp, and Haskell. Created by Andreas Rumpf in 2008, Nim was initially named “Nimrod” before being renamed in 2014. Notable features include a clean, Python-inspired syntax, automatic memory management without the disadvantages of traditional GC’s (ARC/ORC), powerful compile-time metaprogramming through AST-based macros, cross-compilation support, and built-in concurrency mechanisms. The language is suitable for systems programming, general-purpose programming, scripting, game development, and scientific computing.

Latest release

Nim 2.0.4 has been released on 16 April 2024. See the official announcement at Nim 2.0.4

Nim is often characterized by its Efficiency, Expressiveness, and Elegance.

  • Nim generates native, dependency-free executables that do not rely on a virtual machine, enabling compact size and effortless redistribution.
  • The Nim compiler and its generated executables are compatible with all major platforms, including Windows, Linux, BSD, and macOS.
  • Nim’s memory management, inspired by C++ and Rust, is deterministic and customizable with destructors and move semantics, making it well-suited for embedded, hard-realtime systems.
  • Modern concepts such as zero-overhead iterators and compile-time evaluation of user-defined functions, coupled with a preference for value-based datatypes allocated on the stack, result in highly performant code.
  • Nim supports various backends, compiling to C, C++, or JavaScript, making it an ideal choice for both backend and frontend needs. An optional LLVM backend is also available, enabling further performance enhancements on supported systems and bypassing the need for intermediate C or C++ code.
  • Nim is self-contained, as both the compiler and the standard library are implemented in Nim itself.
  • With a powerful macro system, Nim allows direct manipulation of the AST, providing nearly limitless possibilities.
  • Nim features a modern type system, complete with local type inference, tuples, generics, and sum types.

Features

Nim boasts several key features that make it an attractive language for developers:

  • Statically typed: Nim is a statically typed language, which means that type checking is performed at compile time, reducing the likelihood of runtime errors.
  • High-level syntax: Nim’s syntax is clean, concise, and expressive, drawing inspiration from languages like Python and Haskell.
  • Memory Management: Nim offers multiple automatic memory management strategies. Traditional garbage collection (–mm:refc) can be optionally substituted with a fully deterministic, destructor-based memory management (–mm:arc, –mm:orc), which circumvents common GC issues such as execution pauses (“stop the world”) and increased executable size due to the GC runtime system. ORC memory management operates effectively even with cyclic data structures and serves as the default option for Nim 2.0. Traditional GC remains available, and manual memory management is also possible.
  • Metaprogramming: Nim allows for powerful compile-time metaprogramming through its macro system, enabling developers to write generic, reusable code.
  • Cross-compilation: Nim supports cross-compilation, making it possible to compile code for different platforms and architectures.
  • Performance: Nim compiles to C, C++, or JavaScript, resulting in high-performance executables that rival the speed of native C and C++ applications. An optional LLVM backend can be used as well.
  • Concurrency: Nim provides built-in support for parallel and concurrent programming with its async/await and parallel statement features.
  • Nim features a top-notch JavaScript backend, enabling seamless targeting of both client-side and server-side applications simultaneously.
  • Nim implements a small core language with a powerful set of metaprogramming features.

Syntax

Nim’s syntax is inspired by Python, making it easy to read and write. Some notable syntax features include:

  • Indentation-based scoping: Like Python, Nim uses indentation to define blocks of code, eliminating the need for curly braces.
  • Type inference: Nim can infer the type of a variable based on its value, allowing for more concise code.
  • First-class functions: Functions are first-class citizens in Nim, allowing them to be assigned to variables, passed as arguments, or returned as values from other functions.
  • Multiple dispatch: Nim supports multiple dispatch, which means that functions can be overloaded based on the number of arguments and their types.
  • An intriguing feature shared by Nim and D-lang is the method call syntax, originally termed “Uniform Function Call Syntax” (UFCS) in the D language. This feature merges the traditional imperative programming style with the occasionally more convenient OOP syntax. Instead of len(myStr), we can alternatively write mystr.len() or simply mystr.len. In this case, the string parameter assumes the role of self parameters in OOP code, and this notation also works with additional parameters. For example, write(file, data) is equivalent to file.write(data). The Nim compiler recognizes each notation and generates identical code, allowing for OOP style without necessitating the use of actual classes. This works even for fundamental data types like integer numbers, so abs(i), i.abs(), or i.abs can all be utilized.
  • Object-Oriented Programming (OOP): Similar to other modern programming languages such as Go and Rust, Nim accommodates OOP program design, featuring inheritance and runtime method dispatch. However, it does not impose this coding style on programmers.
  • Global Namespaces: In Nim, modules are typically imported using statements like “import strutils” rather than the qualified form “from strutils import split, join, …”. This approach is convenient, as it allows for the usage of split(myString) or myString.split without the need to prefix the function name with the module name, as in stringutils.split(myString). For those accustomed to untyped languages like Python, this unqualified import may seem unusual. However, since Nim is a statically and strongly typed language, function overloading results in namespace conflicts only in very rare cases. These conflicts are reported by the compiler and can be easily resolved by applying a module name prefix when necessary. For constants or enumeration types, name conflicts are more likely, so qualified names are typically employed for these data types. Regrettably, qualified import conflicts with the method call syntax: while strutils.split(myString) is possible, myString(strutils.split) is not allowed.
  • Case Sensitivity: Historically, Nim was a fully style-insensitive language, which meant that it was not case-sensitive, underscores were disregarded, and there was no differentiation between foo and Foo. However, since version 1.0 in 2019, the first letters of symbols are compared in a case-sensitive manner, while other letters are compared case-insensitively within the ASCII range and underscores are ignored. This unconventional approach to identifier comparisons, known as “partial case-insensitivity,” offers several advantages over traditional case sensitivity: It permits programmers to predominantly use their preferred spelling style, whether it be humpStyle or snake_style, and ensures that libraries created by different programmers do not utilize incompatible conventions. A Nim-aware editor or IDE can display the identifiers according to the user’s preference. Additionally, this approach liberates the programmer from memorizing the precise spelling of an identifier. The exception for the first letter enables common code like var foo: Foo to be parsed unambiguously. It is worth noting that the compiler option –styleCheck:off|hint|error can generate hints or errors for Nim identifiers that do not conform to Nim’s official style guide, and –styleCheck:usages enforces consistent spellings of identifiers without imposing the style on declarations.

Metaprogramming

Nim’s macro system offers powerful compile-time metaprogramming capabilities. These macros function as code generators during the compilation process, empowering developers to create more expressive and versatile code. Nim’s macro system is Turing-complete, signifying its ability to express any computation that a Turing machine can perform. Common applications of macros in Nim encompass code generation, domain-specific languages, and optimization.

The metaprogramming features in Nim provide support for generics, templates, and macros, allowing for the extension of Nim with various programming paradigms and helping developers minimize boilerplate code. The standard library incorporates async-await using these metaprogramming features, and the Nim community has developed numerous packages implementing diverse programming paradigms.

Standard Library

Nim’s standard library is extensive, providing modules for various tasks, including:

  • Data structures: Lists, sets, hash tables, and more
  • File I/O: Reading, writing, and manipulating files and directories
  • Networking: Sockets, HTTP, and other network protocols
  • Concurrency: Threads, locks, and async I/O
  • Mathematics: Basic math operations, random number generation, and more
  • Cryptography: Hashing, encryption, and more
  • JSON and XML: Parsing and generating JSON and XML data
  • Regular expressions: Pattern matching and manipulation
  • Dates and times: Timezone-aware date and time operations

Community and Ecosystem

Nim has an active community with many resources available for learning and using the language:

  • Official website: Nim - Provides documentation, downloads, and other resources for Nim developers.
  • GitHub repository: GitHub - The official source code repository for the Nim compiler and standard library.
  • Nimble package manager: Nimble is the official package manager for Nim, making it easy to install and manage third-party libraries.
  • Forums: The Nim Community Forum provides a platform for users to discuss the language, share projects, and ask questions.
  • Discord and IRC channels: Real-time chat channels for Nim users to collaborate and seek assistance.
  • Books and tutorials: Several books and online tutorials are available for learning Nim, catering to various skill levels and interests.
  • Conferences and meetups: annual conferences, such as NimConf, and local meetups help bring the community together and promote the exchange of ideas and experiences.

Notable Projects and Applications

Nim has been used to create various applications, libraries, and frameworks, demonstrating its versatility and power. Some notable examples include:

  • Nim Skull: A Nim-based programming language
  • NLVM: LLVM-based compiler backend
  • Regex: Pure Nim regex engine
  • NPeg: Pure Nim PEG’s implementation
  • Pixie: Pure Nim full-featured 2d graphics library
  • Futhark: Automatic wrapping of C headers
  • Moe: A command-line-based editor inspired by Vim.
  • Chronos: Efficient asynchronous programming
  • NimForUE: Plugin for UE5 with native performance
  • Nitter. An alternative Twitter front-end
  • Atlas: Package cloner
  • Malebolgia: Simplifies the implementation of concurrent and parallel programming
  • HappyX: Macro-oriented asynchronous full-stack web-framework

Comparison to Other Languages

Nim can be compared to other programming languages in terms of its syntax, performance, and features:

  • Syntax: Nim’s syntax is similar to Python, making it easy to learn for Python developers. However, it also incorporates elements from other languages like Lisp, Haskell, ADA, and the Wirthian language family (Pascal/Modula/Oberon).
  • Performance: Due to its compiled nature, Nim’s performance is comparable to languages like C and C++. However, its high-level syntax and features make it more expressive and easier to use than those languages.
  • Features: Nim offers a unique blend of features, such as metaprogramming and cross-compilation, that set it apart from other languages. Its focus on performance and expressiveness makes it suitable for a wide range of applications, from systems programming to web development.

Conclusion

Nim is a powerful and versatile programming language that combines the performance of low-level languages with the expressiveness of high-level languages. Its clean syntax, extensive standard library, and powerful metaprogramming capabilities make it an attractive choice for developers seeking a modern, efficient language for their projects. With a growing community and ecosystem, Nim is poised to make a significant impact on the programming landscape.