View source for Slim instance declaration

== All instance declarations should be slim. ==

This means
* Instance declarations (and default definitions) should never contain non-trivial function definitions.
* Instance declarations (and default definitions) should only provide "plumbing" to make existing functions accessible via the type class resolution mechanism.
* The "plumbed" functions should always be exported (since instances are always exported).

Since the naming will not always be straight-forward,
the last point is particularly important
and would enable more re-use
and less re-invention of mostly trivial wheels.


== See also ==

* Haskell-Cafe: [http://www.haskell.org/pipermail/libraries/2006-September/005791.html Disclipline for re-use: Slim instances]

[[Category:Style]]