# XO0408: const initializer is not a compile time value

A `const` initializer may use only literals, other constants, struct and enum construction, and collection literals of those. Calls and runtime values such as parameters are not compile time values. Use a `let` binding, or compute the value with a function. See core 3.1.

## Example

```xo
fn g() -> Int { 1 }

const X = g()
```

## Fix

```xo
const X = 1
```

Run `xo explain XO0408` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).