# DRecTail::not-a-desc


**Key:** `DRecTail::not-a-desc`

**Category:** description · **Severity:** error

**Source:** [`src/diag/hints.nix:856`](https://github.com/kleisli-io/nix-effects/blob/main/src/diag/hints.nix#L856)

the tail position of `rec` must itself be a description, not an ordinary term. Continue the spine with `descRet`, `descArg`, `descRec`, `descPi`, or `descPlus`.

## Example

`Hint::DRecTail::not-a-desc` means the `DRecTail` position uses an ordinary term where the checker needs a Desc. The example shows the failing form first, then one way to give the checker the missing structure.

```nix
# Bad: the tail after a recursive position is a term.
descRec i (natLit 0)

# Better: continue with another description.
descRec i (descRet i)

```


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