# Duration

> A typed time span with arithmetic and timedelta interop.

Source: https://docs.pyrula.io/primitives/duration/

`Duration` is an immutable, hashable time span backed by an `i64` nanosecond count.

```python
from pyrula import Duration

Duration.millis(250)        # integer units: nanos, micros, millis
Duration.seconds(1.5)       # float units: seconds, minutes, hours, days
Duration.seconds(0.5) == Duration.millis(500)   # True
```

Integer constructors take an exact `int`. Float constructors round to the nearest nanosecond.

```python
d = Duration.seconds(1.5)

d.to_nanos()     # 1_500_000_000
d.to_millis()    # 1500 (truncates)
d.to_seconds()   # 1.5

Duration.seconds(1) + Duration.millis(500)   # Duration(1500ms)
Duration.seconds(1) * 3                      # Duration(3s)
Duration.seconds(1) < Duration.seconds(2)    # True
```

`+`, `-`, `*` and all six comparisons are supported. `repr` uses the largest unit that is exact: `Duration(250ms)`, `Duration(2m)`.

## timedelta

```python
import datetime as dt

Duration.seconds(1).to_timedelta()                           # datetime.timedelta(seconds=1)
Duration.from_timedelta(dt.timedelta(milliseconds=250))      # Duration(250ms)
```

`timedelta` has microsecond resolution, so `to_timedelta()` truncates finer precision.