Slim instance declaration: Difference between revisions
(taken from a post to libraries mailing list) |
(reference to Haskell-Cafe moved to "See also") |
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== All instance declarations should be slim. == | == All instance declarations should be slim. == | ||
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and less re-invention of mostly trivial wheels. | 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]] | [[Category:Style]] | ||
Latest revision as of 06:09, 5 September 2007
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: Disclipline for re-use: Slim instances