# LibTmux.Snapshot.LookupError

- **Package:** libtmux-haskell
- **Language:** Haskell
- **Kind:** data type
- **Source:** https://github.com/libtmux/libtmux-haskell/blob/663e212622a02aa74a9bdc8ff71e2b45fcb1d4d5/internal/LibTmux/Internal/Graph.hs#L243
- **Page:** https://libtmux.org/en/haskell/latest/reference/libtmux-snapshot-t-lookuperror/

```haskell
data LookupError
```

A reference that cannot resolve in the supplied immutable snapshot.
 Missing entities are distinct from a successfully observed empty relation.

## Instances

- instance [Eq](https://hackage.haskell.org/package/base-4.22.0.0/docs/Data-Eq.html#t:Eq) [`LookupError`](/en/haskell/latest/reference/libtmux-snapshot-t-lookuperror/) ([Source](https://github.com/libtmux/libtmux-haskell/blob/663e212622a02aa74a9bdc8ff71e2b45fcb1d4d5/internal/LibTmux/Internal/Graph.hs#L248))

- instance [Show](https://hackage.haskell.org/package/base-4.22.0.0/docs/Prelude.html#t:Show) [`LookupError`](/en/haskell/latest/reference/libtmux-snapshot-t-lookuperror/) ([Source](https://github.com/libtmux/libtmux-haskell/blob/663e212622a02aa74a9bdc8ff71e2b45fcb1d4d5/internal/LibTmux/Internal/Graph.hs#L248))

## Members

### Other members

- [`ForeignGeneration`](/en/haskell/latest/reference/libtmux-snapshot-v-foreigngeneration/) (data constructor): The reference belongs to another connection generation.
- [`MissingPane`](/en/haskell/latest/reference/libtmux-snapshot-v-missingpane/) (data constructor): No physical pane with this identity was captured.
- [`MissingSession`](/en/haskell/latest/reference/libtmux-snapshot-v-missingsession/) (data constructor): No session with this identity was captured.
- [`MissingWindow`](/en/haskell/latest/reference/libtmux-snapshot-v-missingwindow/) (data constructor): No physical window with this identity was captured.

## Referenced declarations

- [`LibTmux.Snapshot.LookupError`](/en/haskell/latest/reference/libtmux-snapshot-t-lookuperror/) (data type)