What are “n+k patterns” and why are they banned from Haskell 2010?

Question

When reading Wikipedia\'s entry on Haskell 2010 I stumbled across this:

-- using only prefix notation and n+k-patterns (no longer allowed in Haskell 2010)
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Answer 1

The link provided by trinithis is correct; n+k patterns are no longer included in the Haskell spec.

For more background on n+k patterns in general, scroll about 3/5ths of the way down this page on pattern matching, or check out this short post.