Introduction to Squirrel#

Squirrel is a programming language used in Titanfall 2 and Northstar mods, it is worth noting that the version of squirrel used by titanfall appears to be a modified version of the language, based on version 2.3.0

File format#

All files using squirrel are typically saved as .nut or .gnut, though any extension will be run, as long as it is in the scripts/vscripts/ directory.

when creating mods your mod will typically be a series of functions and callbacks

Squirrel as a typed language#

All variables and functions in squirrel must have a type defined on declaration

function dosomething()

is only acceptable in untyped scripts. In general, prefer the following:

void function dosomething()

Similarly when declaring a variable

funnynumber = 69

will not work, instead use:

int funnynumber = 69

Variable types#

  • void: can be used to define functions that do not return a value, but still do things. most of your functions will be void

  • integer: a whole number

  • float: any floating-point number.

  • string: text. Squirrel does not have native chars, so calling an index of a string will return a number in standart ascii format. e.g. “a”[0] = 97

  • entity: an entity and all its associated information

  • bool: true or false (Squirrel treats null and 0 as false and every other number or object that’s != null as true)

  • array: an ordered list of items indexed from 0, increasing with the number of items such as: 0:”hello”,1:1000,2:entity player

  • table: a list of items with indexes defined on object entry such as: "word":"hello", "kilo":1000", "pilot":entity player.
    You have to create new slots with the <- operator and overwrite values in slots with =. Tables are explained in more detail in the squirrel documentation

  • struct: a series of attributes assigned to a structure and accessed through with structname.variablename

  • var: Var typically refers to variables that lack any stated type, this will cause issues with many functions unless you use the untyped identifier at the start of your file, or if you use expect type(variable) when passing the variable to that function

Content types#

tables and arrays can have their content types specified. If none are given, they will default to var.

For tables you can set the types of their keys and contents.

// table<key_type, value_type> identifier
table<string, entity> players
foreach( entity player in GetPlayerArray() ) // insert every player into the table indexable by their usernames
{
    players[ player.GetPlayerName() ] <- player
}

Arrays can only have their content typed as they will only be indexable by integers.

array<entity> players = GetPlayerArray()

Error

The rsquirrel lexer recognizes the bitwise right shift operator instead of nested content types, so you are required to leave a space between types containing more content types.

array<array<int>> badNested // COMPILE ERROR
array< array<int> > nested