==== ADD ====
<callout type="primary" color="" icon="fa fa-book" title="Synopsis">
----
Concatenate lists and/or elements
</callout>

<callout color="green" icon="fa fa-indent" title="Stack Diagram">
----
^  __Input Stack__  ^^  ^  __Output Stack__  ^
|  **L<sub>1</sub>**  |  **L<sub>2</sub>**  |  **→**  |  **L<sub>concat</sub>**  |
|  **L<sub>1</sub>**  |  **O**  |  **→**  |  **L<sub>1-upd</sub>**  |
|  **O**  |  **L<sub>2</sub>**  |  **→**  |  **L<sub>2-upd</sub>**  |
|  **O<sub>1</sub>**  |  **O<sub>2</sub>**  |  **→**  |  **L<sub>new</sub>**  |
|  //Level 2//  |  //Level 1//  |  //→//  |  //Level 1//  |

{{page>manual:chapter6:aux:legend&nofooter&noeditbtn&inline}}

| **Keyword type**  | [[manual:chapter5:basics#commands|Command]]  ||
| **Parallel list processing capabilities**  | [[manual:chapter5:listproc#group-2commands-that-must-use-dolist-to-parallel-process|Group 2]]  | //Commands that must use //''[[manual:chapter6:lists:cmd_cmddolist|DOLIST]]''// to parallel process//  |
| **Affected by flags**  | //None//  ||














</callout>

<callout color="orangered" icon="fa fa-comment" title="Description">
----
The ''ADD'' command concatenates lists or adds an element to a new list. It's not necessary that either the first or the second argument is a list: in this case ''ADD'' will create a new list containing both: in other words, single objects are treated as one-element lists.
</callout>

<callout type="warning" icon="true" title="Compatibility">
----
''ADD'' is not fully equivalent to its **userRPL** counterpart.

In particular:

  * in **userRPL** list concatenation is performed by the ''[[manual:chapter6:operators:cmd_ovr_add|+]]'' operator, while ''ADD'' is the command to parallel process the addition;
  * in **userRPL** at least one of the arguments must be a list.
</callout>

<callout type="info" icon="true" title="Usage">
----
**__Input__**
<code>
4:                                      
3:                                      
2:                           { 1 1 2 3 }
1:                            { 5 8 13 }
…………………………………………………………………………………………………………
ADD                                     
</code>
\\
**__Output__**
<code>
4:                                      
3:                                      
2:                                      
1:                    { 1 1 2 3 5 8 13 }
…………………………………………………………………………………………………………
                                        
</code>
</callout>

<callout color="darkgray" icon="fa fa-hand-o-right" title="Related Commands">
----
{{page>manual:chapter6:lists&nofooter&noeditbtn&inline}}
</callout>