# E4139

This expression has type that cannot be implicitly ignored. Use `ignore(...)` or
`let _ = ...` to explicitly ignore it.

`Unit` type can be implicitly ignored.

## Erroneous example

For example,

```{literalinclude} /sources/error_codes/4139_error/top.mbt
:language: moonbit
```

The code here show a deeper problem of the logic of the code: discarding the
result makes the computation useless.

## Suggestion

If you do want to discard the result, use `ignore(..)` or `let _ =` to
explicitly discard the value.

```{literalinclude} /sources/error_codes/4139_fixed/top.mbt
:language: moonbit
```