# LibTmux.Snapshot.lookupSession

- **Package:** libtmux-haskell
- **Language:** Haskell
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-haskell/blob/663e212622a02aa74a9bdc8ff71e2b45fcb1d4d5/src/LibTmux/Snapshot.hs#L103
- **Page:** https://libtmux.org/en/haskell/latest/reference/libtmux-snapshot-v-lookupsession/

```haskell
lookupSession
  :: Snapshot -> SessionRef -> Either LookupError Session
```

Signature types: [`Snapshot`](/en/haskell/latest/reference/libtmux-snapshot-t-snapshot/), [`SessionRef`](/en/haskell/latest/reference/libtmux-snapshot-t-sessionref/), [`Either`](https://hackage.haskell.org/package/base-4.22.0.0/docs/Data-Either.html#t:Either), [`LookupError`](/en/haskell/latest/reference/libtmux-snapshot-t-lookuperror/), [`Session`](/en/haskell/latest/reference/libtmux-snapshot-t-session/).

Resolve a session in this snapshot. Missing and foreign refs are errors.

## Referenced declarations

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