# Field::refinement-failed


**Key:** `Field::refinement-failed`

**Category:** refinement · **Severity:** error

**Source:** [`src/diag/hints.nix:900`](https://github.com/kleisli-io/nix-effects/blob/main/src/diag/hints.nix#L900)

the field's value violates the field type's refinement predicate

## Example

`Hint::Field::refinement-failed` means the `Field` position contains a value that fails the refinement predicate. The example shows the failing form first, then one way to give the checker the missing structure.

```nix
# Bad: the field has the right base type but fails its predicate.
User.validate { age = -1; }

# Better: satisfy the refinement predicate.
User.validate { age = 42; }

```


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