Function declaration looks like:

Tyl Symbolizer will replace ':' with '»', the function symbol:

Each function has a name. Here we declare the greet function. The symbol '»', is used as function symbol in Tyl programs, and comes at the end of function signature.

Each function has its own list of statements, that are run upon function call. So let's add a statement:

While it is not mandatory, function statements are typically written with an indentation regards to their enclosing function section.

If a function has only one statement, it is posible to write the statement right after the function symbol, in the same line. This is called a one line function:

If a function has more than one statement, all function statements should be written in the lines that come after the function declaration line:

If Tyl program has functions, after it runs its statements it will run the first function in the program, provided that it does not contain any parameter.

Let's say we call the first function 'go':

go and greet functions:

Functions can be called from another function. Let's say we want to call greet function from go function, we would write:

The program starts from go function, and calls the greet function. When greet function is called, it starts running its statements. The only statement is print 'Hi', so the program will print 'Hi'.

If we want to greet someone by his name, we would add a function parameter:

The greet function has one parameter 'someone'. We write the parameter right after the function name.

To use greet function with someone parameter:

The line greet 'Oren', is calling the greet function with the string 'Oren', as the someone parameter, thus when the first statement of greet function is executed, someone parameter has the value 'Oren', and the program prints 'Hi Oren'

An example with two parameters:

Function can return a value:

In Tyl, a function will always return the value or result of its last executed statement. So pi function will return the real number 3.1416

Using pi function:

Typically, static variables will be declared in the module statements section of a program. The last code can be changed to:

Here's Perimeter and Area Calculator: