# ::unhandled-other


**Key:** `::unhandled-other`

**Category:** shape · **Severity:** error

**Source:** [`src/diag/hints.nix:951`](https://github.com/kleisli-io/nix-effects/blob/main/src/diag/hints.nix#L951)

this intro form has no inference rule — its type is not determined by its syntax alone. Either annotate the term with `ann <term> <type>` to switch the kernel into checking mode, or move it inside a context where an expected type is already known.

## Example

`Hint::unhandled-other` means an introduction form is in inference mode without enough expected type information. The example shows the failing form first, then one way to give the checker the missing structure.

```nix
# Bad: an introduction form reaches inference without context.
infer emptyCtx introForm

# Better: annotate the expected type at the boundary.
infer emptyCtx (ann introForm expectedType)

```


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