REBOL 3 Functions: function

function spec vars body

Defines a user function with local words.

Arguments:

spec [block!] - Optional help info followed by arg words (and optional type and string)

vars [block!] - List of words that are local to the function

body [block!] - The body block of the function

Description

Warning!

The descripton of function given below is up-to-date, however the spec shown above is not current. function was recently adapted from a 3-argument to a 2-argument variant.

This is similar to func, except all set-words are assumed locals. This way, it's not necessary to specify the /local part of the spec, although you still can.

Example:

average: function [block] [
    total: 0
    foreach number block [total: number + total]
    total / (length? block)
]
print average [1 10 12.34]
7.78

total
** Script error: total has no value

If you still desire to create non-local values in the function, use set to set words:

f: function [a] [
    b: a
    set 'c b / 2
]
f 7
3.5

c
3.5

If c still needs to be local, you can add the local refinement:

unset 'c ; make sure it's not set
f: function [a /local c] [
    b: a
    set 'c b / 2
]
f 7
3.5

c
** Script error: c has no value