Squirrel (programming language)
Squirrel is a high level imperative, object-oriented programming language, designed to be a lightweight scripting language that fits in the size, memory bandwidth, and real-time requirements of applications like video games.
| Paradigm | Multi-paradigm: scripting, imperative, functional, object-oriented | 
|---|---|
| Designed by | Alberto Demichelis | 
| First appeared | September 6, 2003 | 
| Stable release | 3.2
   /    February 10, 2022 | 
| Typing discipline | Dynamic | 
| OS | Cross-platform | 
| License | MIT license | 
| Filename extensions | .nut | 
| Website | squirrel-lang | 
| Influenced by | |
| C++, JavaScript, Lua, Python | |
| Influenced | |
| MiniD | |
MirthKit, a simple toolkit for making and distributing open source, cross-platform 2D games, uses Squirrel for its platform.[1] It is used extensively by Code::Blocks for scripting and was also used in Final Fantasy Crystal Chronicles: My Life as a King.[2][3] It is also used in Left 4 Dead 2, Portal 2 and Thimbleweed Park for scripted events and in NewDark, an unofficial Thief 2: The Metal Age engine update, to facilitate additional, simplified means of scripting mission events, aside of the regular C scripting.[4]
Language features
    
- Dynamic typing
- Delegation
- Classes, inheritance
- Higher order functions
- Generators
- Cooperative threads (coroutines)
- Tail recursion
- Exception handling
- Automatic memory management (mainly reference counting with backup garbage collector)
- Weak references
- Both compiler and virtual machine fit together in about 7k lines of C++ code
- Optional 16-bit character strings
Syntax
    
Squirrel uses a C-like syntax.
- Factorial in Squirrel
  function factorial(x)
  {
    if (x <= 1) {
      return 1;
    }
    else {
      return x * factorial(x-1);
    }
  }
- Generators
  function not_a_random_number_generator(max) {
    local last = 42;
    local IM = 139968;
    local IA = 3877;
    local IC = 29573;
    for(;;) { // loops forever
      yield (max * (last = (last * IA + IC) % IM) / IM);
    }
  }
  local randtor = not_a_random_number_generator(100);
  for(local i = 0; i < 10; i += 1)
     print(">"+resume randtor+"\n");
- Classes and inheritance
  class BaseVector {
    constructor(...)
    {
      if(vargv.len() >= 3) {
        x = vargv[0];
        y = vargv[1];
        z = vargv[2];
      }
    }
    x = 0;
    y = 0;
    z = 0;
  }
  class Vector3 extends BaseVector {
    function _add(other)
    {
      if(other instanceof ::Vector3)
        return ::Vector3(x+other.x,y+other.y,z+other.z);
      else
        throw "wrong parameter";
    }
    function Print()
    {
      ::print(x+","+y+","+z+"\n");
    }
  }
  local v0 = Vector3(1,2,3)
  local v1 = Vector3(11,12,13)
  local v2 = v0 + v1;
  v2.Print();
Applications
    
    Applications using Squirrel
    
- Code::Blocks, integrated development environment
- Enduro/X, cluster application server
- Electric Imp, an end-to-end IoT platform[5]
Games using Squirrel
    
- Left 4 Dead 2 [6]
- Thief II (unofficial NewDark engine update) [7]
- Portal 2 [6]
- Alien Swarm [6]
- Titanfall [6]
- Apex Legends [8]
- Nuclear Dawn [6]
- OpenTTD [9]
- GTA IV's IV-MP [10]
- Mafia II's M2-Multiplayer [11]
- Counter Strike: Global Offensive [6]
- Shadow Warrior
- War Thunder
- CRSED: F.O.A.D.
- SuperTux
- Battle Brothers
- Sonic Unleashed (PS2/Wii) [12]
- Contagion [6] (PC)
- Thimbleweed Park [13]
- Simutrans [14]
- Vice City Multiplayer, [15] a mod for Grand Theft Auto: Vice City [16]
- Liberty Unleashed [17]
- Zero no Tsukaima - Muma ga Tsumugu Yokaze no Nocturne (PS2)
- Zero no Tsukaima - Maigo no Period to Ikusen no Symphony (PS2)
- Zero no Tsukaima - Shou-akuma to Harukaze no Concerto (PS2)
- Antinomy of Common Flowers [18]
- Final Fantasy Crystal Chronicles: My Life as a King [2]
History
    
The language was made public in 2003 under the zlib/libpng license.[19] In November 2010, the license was changed to the MIT license to enable the project to be hosted on Google Code.[20][21] It is developed and maintained by Alberto Demichelis.
See also
    
- Lua
- AngelScript
- Python
- ECMAScript
- Ruby
References
    
- MirthKit Developer Wiki Archived 2014-02-11 at the Wayback Machine
- Brandon Boyer (21 February 2008). "Gamasutra - GDC 2008 Event Coverage". gamasutra.com. Gamasutra.
- "Exclusive: Behind The Scenes of Final Fantasy's WiiWare Debut". gamasutra.com. Gamasutra. 23 June 2008. Retrieved 22 September 2011.
- "L4D2 Vscripts - Valve Developer Community". developer.valvesoftware.com. Retrieved 2018-07-06.
- "Electric Imp programming guide". electricimp.com.
- "VScript". valvesoftware.com. 2014-08-20. Retrieved 2015-01-17.
- "NewDark 1.25: Squirrel script?". ttlg.com. 2017-03-20. Retrieved 2019-12-25.
- "WHAT in the hell, is consumable nut? Please help this is an error code I got, have any of you got this before?". reddit.com. 2019-03-24. Retrieved 2021-09-04.
- "AI:Main Page - OpenTTD". wiki.openttd.org. Retrieved 2018-07-06.
- "iv-multiplayer.com". www.iv-multiplayer.com. Archived from the original on 2012-06-07. Retrieved 2018-07-06.
- "m2-multiplayer.com". www.m2-multiplayer.com. Archived from the original on 2013-01-02. Retrieved 2018-07-06.
- "The VG Resource Wiki". wiki.vg-resource.com. Retrieved 2021-09-04.
- "Thimbleweed Park Blog- Engine". blog.thimbleweedpark.com. Retrieved 2018-07-06.
- "Simutrans-Squirrel-API: Main Page". dwachs.github.io. Retrieved 2018-07-06.
- Vice City Multiplayer
- "Welcome To VC-MP website!". Archived from the original on 2006-04-05. Retrieved 2014-05-04.
- "Liberty Unleashed". Retrieved 2019-12-04.
- "th155-decomp". GitHub. Retrieved 2020-10-19.
- "The Squirrel programming language". SourceForge. Retrieved 2018-07-06.
- "Moving to code.google.com and MIT License - The Language - Squirrel - The Programming Language". forum.squirrel-lang.org. Retrieved 2018-07-06.
- "Google Code Archive - Long-term storage for Google Code Project Hosting". code.google.com. Retrieved 2018-07-06.
