# XO0156: `${` without a matching `}` in the same string

Inside a string, `${` starts an interpolated expression that must be closed by `}` before the string ends. If a literal `${` is meant, escape the dollar sign: `\${`. A `$` not followed by `{` is always literal. See core 1.6.

## Example

```xo
fn f(b: Int) -> Str {
  "a ${b"
}
```

## Fix

```xo
fn f(b: Int) -> Str {
  "a ${b}"
}
```

Run `xo explain XO0156` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).