add tag

Category: ephemeral logic tag

Obtains the result of adding multiple values together.

The add tag can sum all the values in a list, or sum a list of values against a single value, or sum two lists of values (such as two equal-sized vectors) pairwise against each other.

Sample usage

<add 1,1> produces 2.

<add 1 with=1> produces 2.

<add 1,10,-2 with=2> produces 3,12,0.

<add 2 with=1,10> produces 3,12.

<add 2,1 with=100,200> produces 102,201.

<add 2,1 with=1,10,20> produces invalid.

Fields

Primary field

Category: vector field

The tag's primary field takes a list of one or more values. When the (optional) with field is not used, the result produced by the tag is the sum of all values in the primary field.

Secondary fields

with: Optional. Takes a second value or list of values for vector or distributive addition.

Behaviour

When the tag is complete, it produces out a value for one or more results of addition. The tag's lifetime then ends.

Depending on usage, the add tag can be used to perform simple addition (summing two or more values together), distributive addition (adding one value to a set of values), or vector addition (adding two sets of values).

The mode of operation depends on whether the with field is specified, and whether one value or multiple values are present in the primary and with fields.

The following describes this behaviour in detail. But simply refer to the sample usage examples above for examples.

Simple addition

If the with field is not used (simplest case), all values in the primary field are summed together from left to right.

Numerical values are summed together using arithmetic addition.
Values of null are treated similar to zero when added to numbers.
Any text string is concatenated to the result of addition of values to the left of it.
Values of inf always produce a resulting value of inf.
Values of true, false or invalid are invalid in addition and produce a result of invalid.

Distributive addition

If the with field is specified with exactly one value element, the value in the with field is added to the first element in the primary field to produce the first result, then the with field value is added to each subsequent element in the primary field to produce each subsequent result in the same way.
If the primary field contains exactly one value element and the with field is specified with multiple value elements, the first value in the with field is added to the primary field value to produce the first value in the result, then each subsequent value in the with field is added to the primary field value to produce each subsequent result in the same way.

Vector addition

If both the primary and with fields contain multiple values, and both fields contain an equal number of elements, the two fields are added according to vector addition: the first element of the with field is added to the first element of the primary field to produce the first value in the result, then the second element in the primary field is paired with the second element in the with field, and so on.
If both the primary and with fields contain multiple values but the number of elements in each field is different, the tag produces invalid.

Example

The following code, when output to an ioL console, presents the user with a simple on-screen calculator.

<a:input 0> + <b:input 0> = <result:box 0></p>
<button {Evaluate} onClick=
    <result|add <num a>, <num b>>
>

The following non-interactive illustration shows what would be presented to the user in the console. When run in a real console, the user would be able to change the two initial values of 0 to any number and click the "Evaluate" button to add them together and see the result.

0 + 0 = 0 Evaluate