Scripting introduction

MSE uses a custom scripting language to add complicated behaviour to [[type:field]]s and [[type:style]]s.

This documentation assumes that the reader has some programming experience.
In particular it is assumed that you know what 'functions', 'variables' and 'operators' are.

Scripts in MSE are usually small, just a few lines.
A piece of script code is also called an ''expression''.
Expressions can be ''evaluated'' to give a result.
For example the expression @1 + 1@ will evaluate to @2@.

An important idea behind MSE is that it tries to be ''pure'',
there are no global variables and there is no way to change properties of objects.
This means that when you evaluate an expression the result is always the same (unless it contains variable assignments).

Basic elements of scripts are ''constants''.
A constant is something with a fixed value.
Possible constants are:
! Syntax		Type
| @nil@			Nothing
| @true@, @false@	[[type:boolean]]
| @123@			[[type:int]]
| @123.5@		[[type:double]]
| @"abc"@		[[type:string]]
| @rgb(255,0,0)@	[[type:color]]
| @[a,b,c]@		[[type:list]]
Note: Strings, list and colors don't have to be constants, they can contain other code.

The @nil@ value has a special meaning, it is 'nothing'.
Adding @nil@ to something has no effect (it returns 'something'), calling @nil@ as a function just returns the input, etc.

<div style="text-align:right;">next: <a href="operators">Operators &rarr;</a></div>
