Frequently Asked Questions

General questions

Why yet another programming language?

Nim is one of the very few programmable statically typed languages, and combines the speed and memory efficiency of C, an expressive syntax, memory safety and multiple target languages.

How stable is Nim?

The compiler and stdlib are actively under development and have a suite of test cases to ensure ongoing stability. Regular releases are posted every three to six months that can be used as a base for projects requiring a stable foundation. Breaking changes are rare but are documented in detail and can typically be managed with minimal effort. The compiler also highlights deprecated features to provide sufficient notice and transition time through changes.

How about security and memory safety?

Nim provides memory safety by not performing pointer arithmetic, with optional checks, traced and untraced references and optional non-nullable types. It supports Valgrind through the koch tool, and taint analysis.

How is Nim licensed?

The Nim compiler and the library are MIT licensed. This means that you can use any license for your own programs developed with Nim.

What about JVM/CLR backends?

JVM/CLR support is not in the nearest plans. However, since these VMs support FFI to C it should be possible to create native Nim bridges, that transparently generate all the glue code thanks to powerful metaprogramming capabilities of Nim.

What about editor support?

• Visual Studio Code: Official extension https://marketplace.visualstudio.com/items?itemName=NimLang.nimlang
• VSCodium/OpenVSX: https://open-vsx.org/extension/nimsaem/nimvscode
• Emacs: https://github.com/nim-lang/nim-mode
• Vim: https://github.com/zah/nimrod.vim/
• NeoVim: https://github.com/alaviss/nim.nvim
• Helix: https://github.com/nim-lang/langserver
• QtCreator (4.1+): Included as experimental plugin.
• Scite: Included
• Gedit: The Aporia .lang file.
• Geany: Included
• jEdit: https://github.com/exhu/nimrod-misc/tree/master/jedit
• TextMate: https://github.com/textmate/nim.tmbundle
• Sublime Text: https://github.com/Varriount/NimLime
• LiClipse: http://www.liclipse.com/ (Eclipse based plugin)
• Howl: Included
• Notepad++: https://github.com/jangko/nppnim/releases
• Micro: Included
• Atom: https://atom.io/packages/nim
• JetBrains IDEs: https://plugins.jetbrains.com/plugin/15128-nim
• Kakoune: Included
• For editors with LSP (Language Server Protocol) support (requires a separate syntax/indenting plugin): https://github.com/PMunch/nimlsp

What have been the major influences in the language’s design?

The language borrows heavily from (in order of impact): Modula 3, Delphi, Ada, C++, Python, Lisp, Oberon.

Why is it named proc?

Procedure used to be the common term as opposed to a function which is a mathematical entity that has no side effects. And indeed in Nim func is syntactic sugar for proc {.noSideEffect.}. Naming it def would not make sense because Nim also provides an iterator and a method keyword, whereas def stands for define.

Compilation FAQ

Which option to use for the fastest executable?

For the standard configuration file, -d:danger makes the fastest binary possible while disabling all runtime safety checks including bound checks, overflow checks, nil checks and more; for most cases -d:release should be enough. If supported by your compiler, you can also enable link-time optimization for an even faster executable: --passc:-flto or -d:lto on Nim 1.4+

Which option to use for the smallest executable?

For the standard configuration file, -d:danger -d:strip --opt:size does the trick. If supported by your compiler, you can also enable link-time optimization the same way as described in the previous answer.

How do I use a different C compiler than the default one?

Edit the config/nim.cfg file. Change the value of the cc variable to one of the following:

Abbreviation	C/C++ Compiler
gcc	GNU C compiler
clang	Clang compiler
vcc	Microsoft’s Visual C++
icc	Intel C compiler
llvm_gcc	LLVM-GCC compiler
tcc	Tiny C compiler
bcc	Borland C compiler
envcc	Your environment’s default C compiler

Other C compilers are not officially supported, but might work too.

If your C compiler is not in the above list, try using the environment’s default C compiler (envcc). If the C compiler needs different command line arguments try the --passc and --passl switches.