====== Functions ======

TIScript supports named and anonymous (lambda) functions.




===== Named functions =====
Named functions are declared using following syntax:
<code tiscript>
function <function-name> ( <parameters> )
{
  //...function body
}
</code>
Where:
  * ''<function-name>'' is a function name, either: 
    * simple ''<nmtoken>'' , or 
    * compound name: ''<nmtoken1> ['.' <nmtoken2> ['.' <nmtoken3> ['.' ... <nmtokenN> ]]]'' ((Declaration of function with compound name is a short form the following\\ ''name1.name2.name3. ... .nameN = function( <parameters> ) { <statements> }''))  
  * ''<parameters>'' is a list of formal parameters of the function:\\ <code>[<parameter-name1> [, <parameter-name2> [, ... <parameter-nameN> ]]]</code>



===== Anonymous functions =====
Anonymous function can be declared in place using following forms:
  - classic JavaScript form:\\ <code tiscript> function ( <parameters> ) { <statements> }</code>
  - single expression lambda function form:\\ <code tiscript> : <parameters> : <statement> </code>
  - block lambda function form:\\ <code tiscript> : <parameters> { <statements> } </code>

Nested functions (functions inside functions) are allowed.


===== Optional parameters =====
The language supports optional parameters in function declarations:





==== Parameters with default values ====

Some parameters in the function declaration may have default value defined, for example:
<code tiscript>
function Foo( a, b, c = 12)
{
  return a + b + c;
}
</code>
Such function can be called with either two:
<code tiscript>
var r1 = Foo(1,2); // r1 will be equal to 15 here
</code>
or three actual parameters:
<code tiscript>
var r2 = Foo(1,2,3); // r2 will be equal to 6 here
</code>

Parameter with predefined value must not have non-optional parameter on its right in the list. In other words only last (or all) parameters can have default values.




==== Varargs ====
a.k.a. Parameter vectors  

There are situations when you will need to define functions with number of parameters unknown upfront.
Such functions can be declared as:
<code tiscript>
function Bar(a,b,rest..)
{
  var total = a + b; 
  for( var n in rest ) total += n;
  return total; 
}
</code>
In runtime variable ''rest'' will contain array with actual parameters passed into the function. So after
<code tiscript>
var r1 = Bar(1,2,3,4); 
</code>
''r1'' will contain value ''10'', and after 
<code tiscript>
var r2 = Bar(1,2); 
</code>
''r2'' will contain value ''3''