REBOL 3 Docs Guide Concepts Functions Datatypes Errors
  TOC < Back Next >   Updated: 6-Feb-2009 Edit History  

REBOL 3 Concepts: Blocks: Blocks of Blocks

Pending Revision

This document was written for R2 and has yet to be revised for R3.

When a block appears as a value within another block, it counts as a single value regardless of how many values it contains. For example:

values: [
    "new" [1 2]
    %file1.txt ["one" ["two" %file2.txt]]
probe values
["new" [1 2] %file1.txt ["one" ["two" %file2.txt]]]

The length? of values is four. The second and fourth values are counted as single values:

print length? values

The block values within the values block can be used as a block as well. In the following examples, second is used to extract the second value from values.

To print the block, type:

probe second values
[1 2]

To get the length of the block, type:

print length? second values

To print the datatype of the block, type:

print type? second values

In the same way, series operations can be performed on other types of series values in blocks. In the following examples, pick is used to extract %file1.''txt from values.

To look at the value, type:

probe pick values 3

To get the length of the value:

print length? pick values 3

to see the datatype of the value:

print type? pick values 3

  TOC < Back Next > - WIP Wiki Feedback Admin