Functions

Functions must be declared before they are used and so must be written on top of your program. However, this is not required if a function is called from within another function.

func

Variables inside a function created with func are global. They are the seen by the entire program.

A function is created with func as follows:

<function name>: func [<argument1> <argument2> ... <argument n>] [ <actions performed on arguments>]

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Demonstrating that variables are global:

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function

function makes its variables local, i.e. it hides (shades) the variables inside it from the rest of the program.

Same program as above, only using function instead of func:

Different results:

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Forcing variables to be global with /external refinement:

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Defining the argument type:

You can force your arguments to be of a certain datatype:

*** Script Error: mysum does not allow float! for its a argument
*** Where: mysum
*** Stack: mysum 
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You may allow multiple datatypes:

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Or use an upper class of datatypes:

Returning values from functions:

The return value of a function is either the last value evaluated by the function or one explicitly determined by the word return:

Last evaluation example:

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return example:

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Creating your own refinements:

You can create refinements to you functions, like the native refinements of Red: <myfunction>/<myrefinement>. The refinements are boolean values that are checked by the function:

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Note that arguments are not mandatory for refinements.

Assigning functions to variables

To assign a function to a variable (a word) you must precede the function with a colon: <word>: :<function>

does

If your routine just do something with no arguments and no local variables, use the word does :

Hello
Stranger
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has

If your routine uses no external arguments but has local variables, use the word has. has turns the argument into a local variable. Compare the three programs below. The first uses has with no argument, hence number is a global variable. The second gives number as argument, making it local. And the third shows that a function with argument need that argument to be sent by the calling event.

exit

Exits a function without returning any values.