Functions are ubiquitous in TL Script. A function is a script expression that requires one or more inputs to be calculated. Most scripts used to parameterize user interface components in Top-Logic must be written as functions. The script usually expects an input (argument) from surrounding components. A function consists of the declaration of a parameter which names the expected input and an expression which refers to this parameter:

x -> $expr

Defines a function that expects an argument x and produces a value by evaluating the expression expr. In the expression, the value of the function argument can be accessed using the syntax $x (see Variables).

A function that expects multiple arguments is written as follows:

x -> y -> $expr-using-$x-and-$y

Functions can also be stored in a variable to be called at a later time (see Function application).

{
   myFunc = x -> $x * 5;
}

Examples

For information on calling functions, see Function application.

Function with one parameter

	x -> 5 * $x

Output: /

The input for x is multiplied by 5.

Function with two parameters

	x -> y -> $x * $y

Output: /

Multiplies the inputs of x and y.

Function in one variable

	{
   multiply = x -> 5 * $x;
}

Output: /

The function for mulitplication is stored in the variable multiply. This can be accessed with $multiply to execute it with apply(), for example.