# bigi

Arbitrary precision integer arithmetic for Gleam.

In the Erlang target, all integers are automatically “big integers” that are subject to arbitrary precision arithmetic. This means there is no need for this package if you are only targeting Erlang.

In JavaScript, Gleam’s `Int`

type corresponds to the `number`

type, which is implemented using
floating-point arithmetic. That means it’s subject to the following limits:

- Maximum safe integer and minimum safe integer beyond which the accuracy of arithmetic suffers, and
- maximum value
and
minimum value
beyond which the numbers are converted to
`Infinity`

or`-Infinity`

.

This package thus provides big integers for the JavaScript target and additionally provides a
consistent interface for packages that target both Erlang and JavaScript. In Erlang, regular
integers are used. In JavaScript, the
`BigInt`

type is used.

```
gleam add bigi
```

```
import bigi
pub fn main() {
bigi.power(
bigi.from_int(2),
bigi.from_int(65_535)
)
// Ok(1001764965203423232489536175780127875223912737784875709632508486855447029778...)
}
```

Further documentation can be found at https://hexdocs.pm/bigi.

## Limitations

Erlang does have a limit for big integers at around 4 megabits, as demonstrated below:

```
import bigi
pub fn main() {
// Works
bigi.power(bigi.from_int(2), bigi.from_int(4_194_239))
// Blows up
bigi.power(bigi.from_int(2), bigi.from_int(4_194_240))
}
```

For Node.js, the limit is somewhere higher.

`bigi`

has no facilities to warn about or handle errors due to these system limits. It is up to the developer
to be mindful of them.

## Development

```
gleam run # Run the project
gleam test # Run the tests
gleam shell # Run an Erlang shell
```