# setproduct Function

The `setproduct`

function finds all of the possible combinations of elements
from all of the given sets by computing the
Cartesian product.

```
setproduct(sets...)
```

This function is particularly useful for finding the exhaustive set of all combinations of members of multiple sets, such as per-application-per-environment resources.

```
> setproduct(["development", "staging", "production"], ["app1", "app2"])
[
[
"development",
"app1",
],
[
"development",
"app2",
],
[
"staging",
"app1",
],
[
"staging",
"app2",
],
[
"production",
"app1",
],
[
"production",
"app2",
],
]
```

You must past at least two arguments to this function.

Although defined primarily for sets, this function can also work with lists. If all of the given arguments are lists then the result is a list, preserving the ordering of the given lists. Otherwise the result is a set. In either case, the result's element type is a list of values corresponding to each given argument in turn.

## Examples

There is an example of the common usage of this function above. There are some other situations that are less common when hand-writing but may arise in reusable folder situations.

If any of the arguments is empty then the result is always empty itself, similar to how multiplying any number by zero gives zero:

```
> setproduct(["development", "staging", "production"], [])
[]
```

Similarly, if all of the arguments have only one element then the result has only one element, which is the first element of each argument:

```
> setproduct(["a"], ["b"])
[
[
"a",
"b",
],
]
```

Each argument must have a consistent type for all of its elements. If not, Nomad will attempt to convert to the most general type, or produce an error if such a conversion is impossible. For example, mixing both strings and numbers results in the numbers being converted to strings so that the result elements all have a consistent type:

```
> setproduct(["staging", "production"], ["a", 2])
[
[
"staging",
"a",
],
[
"staging",
"2",
],
[
"production",
"a",
],
[
"production",
"2",
],
]
```

## Related Functions

`contains`

tests whether a given list or set contains a given element value.`flatten`

is useful for flattening hierarchical data into a single list, for situations where the relationships between two object types are defined explicitly.`setintersection`

computes the*intersection*of multiple sets.`setunion`

computes the*union*of multiple sets.