Squirrel (programming language)

Squirrel

Paradigm	Multi-paradigm: scripting, imperative, functional, object-oriented
Designed by	Alberto Demichelis
First appeared	September 6, 2003
Stable release	3.1 / March 27, 2016
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 and embedded systems.

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 == 0) { 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

Non-game applications using Squirrel

• Enduro/X Cluster Application server
• Electric Imp An end to end IoT platform ^[5]

Games using Squirrel

History

The language was made public in 2003 under the zlib/libpng license.^[16] In November 2010, the license was changed to the MIT license to enable the project to be hosted on Google Code.^[17][18] It is developed and maintained by Alberto Demichelis.

See also

• Lua
• AngelScript
• Python
• ECMAScript
• Ruby

References

External links

• Official website