> For the complete documentation index, see [llms.txt](https://fluence.gitbook.io/aqua-book/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fluence.gitbook.io/aqua-book/libraries/aqua-lib.md).

# @fluencelabs/aqua-lib

API of protocol-level service (a.k.a builtins)

## Releases

You can find the latest releases of `aqua-lib` [on NPM](https://www.npmjs.com/package/@fluencelabs/aqua-lib) and changelogs are [on GitHub](https://github.com/fluencelabs/aqua-lib/releases)

## API

The most up-to-date documentation of the API is in the code, please [check it out on GitHub](https://github.com/fluencelabs/aqua-lib/blob/main/builtin.aqua)

### Services

`aqua-lib` defines a number of services available on peers in the Fluence Network:

* `Op` - short for "Operations". Functions for data transformation.
* `Peer` - functions affecting peer's internal state
* `Kademlia` - functions to manipulate libp2p Kademlia
* `Srv` - short for "Service". Functions for service manipulation
* `Dist` - short for "Distribution". Functions for module and blueprint distribution
* `Script` - functions to run and remove scheduled (recurring) scripts

## How to use it

### In Aqua

Add `@fluencelabs/aqua-lib` to your dependencies as described in [Libraries doc](/aqua-book/libraries.md), and then import it in your Aqua script:

```haskell
import "@fluencelabs/aqua-lib"

-- gather Peer.identify from all nodes in the neighbourhood
func getPeersInfo() -> []Info:
    infos: *Info
    nodes <- Kademlia.neighborhood(%init_peer_id%, nil, nil)
    for node in nodes:
        on node:
            infos <- Peer.identify()
    <- infos
```

### In TypeScript

`aqua-lib` is meant to be used to write Aqua scripts, and since`aqua-lib` doesn't export any top-level functions, it's not callable directly in the TypeScript.&#x20;

## Patterns

### Functions With A Variable Number Of Arguments

Currently, Aqua doesn't allow to define functions with a variable number of arguments. And  that limits `aqua-lib` API. But there's a way around that.

Let's take `Op.concat_strings` as an example. You can use it to concatenate several strings. `aqua-lib` provides the following signature:

```haskell
concat_strings(a: string, b: string) -> string
```

Sometimes that is enough, but sometimes you need to concatenate more than 2 strings at a time. Happily, under the hood `concat_strings` accepts any number of arguments, so you can redeclare it with the number of arguments that you want:

```haskell
service MyOp("op"):
  concat_strings(a: string, b: string, c: string, d: string) -> string
```

#### List of operations with a variable number of arguments

Here's a full list of other Op-s that you can apply this pattern to

* `Op.concat` - can concatenate any number of arrays
* `Op.array` - wraps any number of arguments into an array
* `Op.concat_string` - concatenates any number of strings