vault: a persistent store for values of arbitrary types

[ bsd3, data, library ] [ Propose Tags ]

A vault is a persistent store for values of arbitrary types. It's like having first-class access to the storage space behind IORefs.

The data structure is analogous to a bank vault, where you can access different bank boxes with different keys; hence the name.

Also provided is a locker type, representing a store for a single element.


[Skip to Readme]
Dependencies base (>1 && <1), containers (>=0.4 && <0.6), hashable (>= && <1.3), unordered-containers (>= && <0.3) [details]
License BSD-3-Clause
Copyright (c) Heinrich Apfelmus 2011-2013
Author Heinrich Apfelmus, Elliott Hird
Maintainer Heinrich Apfelmus <apfelmus at quantentunnel de>
Revised Revision 1 made by HerbertValerioRiedel at Tue Oct 25 21:41:07 UTC 2016
Category Data
Home page
Source repo head: git clone git://
Uploaded by HeinrichApfelmus at Mon Sep 9 12:56:28 UTC 2013
Distributions Arch:, Debian:, Fedora:, FreeBSD:, LTSHaskell:, NixOS:, Stackage:, openSUSE:
Downloads 94933 total (254 in the last 30 days)
Rating (no votes yet) [estimated by rule of succession]
Your Rating
  • λ
  • λ
  • λ
Status Docs uploaded by user [build log]
All reported builds failed [all 1 reports]
Hackage Matrix CI



  • Data
    • Unique
      • Data.Unique.Really
    • Vault
      • Data.Vault.Lazy
      • ST
        • Data.Vault.ST.Lazy
        • Data.Vault.ST.Strict
      • Data.Vault.Strict



Use GHC-specific packages and extensions.


Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info


Note: This package has metadata revisions in the cabal description newer than included in the tarball. To unpack the package including the revisions, use 'cabal get'.

Maintainer's Corner

For package maintainers and hackage trustees

Readme for vault-

[back to package description]

Vault is a tiny library that provides a single data structure called vault.

A vault is a type-safe, persistent storage for values of arbitrary types. Like IORef, I want to be able to store values of any type in it, but unlike IORef, I want the storage space to behave like a persistent, first-class data structure, as appropriate for a purely functional language.

It is analogous to a bank vault, where you can access different bank boxes with different keys; hence the name.

In other words, a vault is an abstract data type with the following basic signature

data Key a
data Vault

newKey :: IO (Key a)
empty  :: Vault
lookup :: Key a -> Vault -> Maybe a
insert :: Key a -> a -> Vault -> Vault
delete :: Key a -> Vault -> Vault

A few common functions for finite maps, like adjust and union, are provided as well.

This library was created thanks to the feedback on my blog post Vault - a persistent store for values of arbitrary types.


The whole thing is available on hackage, so you just have to type

cabal update
cabal install vault


Use the issue tracker or send an email to the maintainer.