# Lists & Maps | EasyNet Docs

Source: https://easynet.run/docs/aal/collections

# Lists & Maps

Store multiple values and look them up by key.

List<T> stores elements of one type; Map<K,V> associates keys with values. Here we count labels and write the result into a map.

## Complete example

Save the example as collections.aal
collections.aal

```
agent Tutorial is Agent
  public
    ability run() -> Int effects()
      labels = ["docs", "tools"]
      labels.append("agents")
      counts = Map<String,Int>{"total": 0}
      counts["total"] = labels.len()
      return counts["total"]
```

[Download .aal](data:text/plain;charset=utf-8,agent%20Tutorial%20is%20Agent%0A%20%20public%0A%20%20%20%20ability%20run()%20-%3E%20Int%20effects()%0A%20%20%20%20%20%20labels%20%3D%20%5B%22docs%22%2C%20%22tools%22%5D%0A%20%20%20%20%20%20labels.append(%22agents%22)%0A%20%20%20%20%20%20counts%20%3D%20Map%3CString%2CInt%3E%7B%22total%22%3A%200%7D%0A%20%20%20%20%20%20counts%5B%22total%22%5D%20%3D%20labels.len()%0A%20%20%20%20%20%20return%20counts%5B%22total%22%5D%0A)

## Syntax explained

Write a list as ["docs", "tools"]. Access with items[0] and add with .append(value).

An explicit map is Map<String,Int>{"total": 0}; read or write using map["total"].

Lists and records have value semantics: assignment and calls clone owned values. Local collection mutation does not require memory.write.

## Build and run
Terminal

```
cargo run --locked --bin aalc -- check collections.aal

cargo run --locked --bin aalc -- build collections.aal -o collections.aalc

cargo run --locked --bin aalc -- run collections.aalc \
  --agent Tutorial --ability run \
  --args '{}' \
  --state-dir .aal-tutorial/collections --invocation collections-1
```

Run with a fresh state directory. The returned value is shown below; the CLI also prints execution information.
Expected result

```
3
```

## Try it yourself

Add labels.append("notes"), rebuild and use a new invocation ID. The returned count should change from 3 to 4.
[Language source and specification](https://github.com/Brain-Cell-Coding/Agent-Assembly-Language/blob/main/docs/ordered-maps.md)