Squirrel (programming language)

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Squirrel
Paradigm	Multi-paradigm: scripting, imperative, functional, object-oriented
Designed by	Alberto Demichelis
First appeared	September 6, 2003; 21 years ago (2003-09-06)
Stable release	3.2  / 10 February 2022; 3 years ago (10 February 2022)
Typing discipline	Dynamic
OS	Cross-platform
License	MIT license
Filename extensions	.nut
Website	squirrel-lang.org
Influenced by
C++, JavaScript, Lua, Python
Influenced
MiniD

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.

MirthKit, a simple toolkit for making and distributing open source, cross-platform 2D games, uses Squirrel for its platform. It is used extensively by Code::Blocks for scripting and was also used in Final Fantasy Crystal Chronicles: My Life as a King. 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.

• 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

Squirrel uses a C-like syntax, albeit inspired by that of Lua as well.

Factorial in Squirrel

local function factorial(x) // Getting function which is factorial, then getting value which is x {   if (x <= 1) {  // if x is less than 1     return 1;  // then the code will just return 1   }   else { // if that doesn't work     return x * factorial(x-1); // then the code will return x times 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(); 

• Code::Blocks, integrated development environment
• Enduro/X, cluster application server
• Electric Imp, an end-to-end IoT platform

The language was made public in 2003 under the zlib/libpng license. In November 2010, the license was changed to the MIT license to enable the project to be hosted on Google Code. It is developed and maintained by Alberto Demichelis.

• Lua
• AngelScript
• Python
• ECMAScript
• Ruby

• Official website