> ## Documentation Index
> Fetch the complete documentation index at: https://errand.nuvrel.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# join

> Join a list of strings into a single string with a separator.

`join(separator, lists...)` concatenates all elements of one or more lists into a single string, with `separator` placed between each element.

## Signature

```
join(separator string, lists... list(string)) string
```

## Example

Build a space-separated list of Go packages and pass it to a build command:

```hcl theme={null}
variable "packages" {
  description = "Go packages to build"
  type        = list(string)
  default     = ["./cmd/api", "./cmd/worker", "./cmd/scheduler"]
}

computed "package_list" {
  description = "Space-separated package list"
  expression  = join(" ", var.packages)
}

task "build" {
  description = "Build all packages"
  commands    = ["go build ${computed.package_list}"]
}
```

With the default value, the command becomes `go build ./cmd/api ./cmd/worker ./cmd/scheduler`.

## Notes

* If all lists are empty, `join` returns an empty string.
* If the combined list has one element, no separator is added.
* Multiple lists are concatenated before joining: `join(", ", list1, list2)` is equivalent to `join(", ", concat(list1, list2))`.