The vault package

[ Tags: 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.


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Dependencies base (>1 && <1), containers (>=0.4 && <0.6), hashable (>= && <1.3), unordered-containers (>= && <0.3) [details]
License BSD3
Copyright (c) Heinrich Apfelmus 2011-2013
Author Heinrich Apfelmus, Elliott Hird
Maintainer Heinrich Apfelmus <apfelmus at quantentunnel de>
Category Data
Home page
Source repository head: git clone git://
Uploaded Mon Sep 9 12:56:28 UTC 2013 by HeinrichApfelmus
Updated Tue Oct 25 21:41:07 UTC 2016 by HerbertValerioRiedel to revision 1   [What is this?]
Distributions Arch:, Debian:, Fedora:, FreeBSD:, LTSHaskell:, NixOS:, Stackage:, Tumbleweed:
Downloads 90638 total (2083 in the last 30 days)
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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




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Maintainer's Corner

For package maintainers and hackage trustees

Readme for vault-

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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


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