The focus package

[Tags:library, mit]

An API for construction of free-form strategies of access and manipulation of elements of arbitrary data structures. It allows to implement efficient composite patterns, e.g., a simultaneous update and lookup of an element, and even more complex things.

Strategies are meant to be interpreted by the host data structure libraries. Thus they allow to implement all access and modification patterns of a data structure with just a single function, which interprets strategies.

This library provides pure and monadic interfaces, so it supports both immutable and mutable data structures.


Versions 0.1.0, 0.1.1, 0.1.2, 0.1.3, 0.1.4, 0.1.5
Dependencies base (>=4.6 && <4.8), loch-th (==0.2.*), placeholders (==0.1.*) [details]
License MIT
Copyright (c) 2014, Nikita Volkov
Author Nikita Volkov <>
Maintainer Nikita Volkov <>
Stability Unknown
Category Containers, Data
Home page
Bug tracker
Source repository head: git clone git://
Uploaded Fri Jun 20 15:55:36 UTC 2014 by NikitaVolkov
Updated Mon May 23 08:54:12 UTC 2016 by phadej to revision 1
Distributions LTSHaskell:0.1.5, NixOS:0.1.5, Stackage:0.1.5, Tumbleweed:0.1.5
Downloads 2914 total (13 in the last 30 days)
0 []
Status Docs available [build log]
Successful builds reported [all 1 reports]




Maintainer's Corner

For package maintainers and hackage trustees