# Arithmetic Expression

Decodal supports arithmetic over concrete numeric values.

```dcdl
{
    workers = 2 + 2;
    timeout = 30.0 / 2;
    port = 8000 + 80;
    negative = -1;
}
```

## Operators

- `+` addition
- `-` subtraction
- `*` multiplication
- `/` division
- unary `-` negation

`*` and `/` bind tighter than `+` and `-`.
Parentheses can be used to make grouping explicit.

```dcdl
2 + 3 * 4     # 14
(2 + 3) * 4   # 20
```

## Numeric behavior

Arithmetic requires concrete `Int` or `Float` operands.
`Int + Int`, `Int - Int`, and `Int * Int` produce `Int` when no overflow occurs.
Mixed `Int` / `Float` arithmetic produces `Float`.
Division always produces `Float`.

Division by zero and integer overflow are evaluation errors.

Arithmetic expressions can be used anywhere a concrete numeric expression is expected, including defaults and numeric constraints.

```dcdl
port = Int & > 4000 + 42 default 8080;
```