# Using a function: calls and arguments

[Syntax and values](README.md)

A **call** asks a function to do its job. The supplied values are its **arguments**; the names that receive them in a function definition are **parameters**. A **signature** summarizes the call shape. [Follow one call step by step](../concepts/parameters-and-arguments.md).

Calling a function means asking it to do its job. The values you give it are its arguments. Some simple calls can also be written in Pliro command form.

Parenthesized calls are expressions:

```text
say("Hello")
let result = length([10, 20, 30])
let value = makeFunction()(4)
```

A call can use an empty argument list and can be nested inside another
expression. Argument lists accept a trailing comma.

For readability, a call used as a whole statement may omit parentheses:

```text
say "Hello"
say "Score:", score
forward 100
```

The command target may be an identifier or member chain, and multiple
arguments require commas. The command and parenthesized forms produce the same
canonical call operation.

Zero-argument calls always need parentheses:

```text
penUp()
clear()
exitApp()
```

Use parentheses when a command's first argument starts with a list, grouping,
or unary sign:

```text
say([1, 2, 3])
say(-1)
say((2 + 3) * 4)
```

An arbitrary expression is also a valid statement. Its value is normally
discarded. Interactive REPL and immediate-console sessions display a non-`none`
top-level expression result.

## Example

```pliro
# language: en
say("Pliro")
say "Pliro", 12
say([1, 2, 3])
```

## Related entries

[Syntax and values](README.md) · [Built-ins](../builtins/README.md) · [Programming guides](../guides/README.md)