The simple-observer package

[ Tags: bsd3, control, library ] [ Propose Tags ]

This is a simple Haskell implementation of the Observer pattern, specified as a typeclass with one example instance (demonstrating synchronous notifications). It is based on Observable.hs by Bastiaan Heeren, originally from

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Versions 0.0.1
Dependencies base (==4.*) [details]
License BSD3
Copyright Andy Gimblett <>
Author Andy Gimblett <>
Maintainer Andy Gimblett <>
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Uploaded Wed Nov 11 22:09:59 UTC 2009 by AndyGimblett
Distributions NixOS:0.0.1
Downloads 524 total (5 in the last 30 days)
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Maintainer's Corner

For package maintainers and hackage trustees

Readme for simple-observer-0.0.1

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This is a Haskell implementation of the Observer design pattern [1,2],
providing a typeclass and an example implementation (Synchronous)
which is perfectly usable in its own right.

This package is based on Observable.hs by Bastiaan Heeren [3],
originally published as part of an exercise [4] for his students.  It
has been modified, extended and packaged by Andy Gimblett [5,6].


* Implement a mechanism for removal of observers.  Consider Tom
  Lokhorst's suggestion on haskell-cafe [7].


2009.11.11 v0.0.1 - first release, renamed from observer to
                    simple-observer in recognition that there are more
                    sophisticated ways to skin this particular cat.

2009.10.30 v0.0.0 - first Cabalised version, unreleased.


[1] Gamma et al: `Design Patterns: Elements of Reusable
    Object-Oriented Software', Addison-Wesley, 1994.