RFC, add Suc to base

hasSuc :: Int -> Maybe Int
hasSuc n = [ n - 1 | n > 0 ]

pattern Suc :: Int -> Int
pattern Suc n <- (hasSuc -> Just n)
  where Suc n = n + 1

with a more general type

Trac metadata

Trac field	Value
Version	8.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
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