haskell@gentoo.org Gentoo Haskell This package provides a canonical anonymous 1-tuple type missing from Haskell for attaching typeclass instances. NOTE: There is also the </package/OneTuple OneTuple package> which by using a boxed @data@-type provides a 1-tuple type which has laziness properties which are more faithful to the ones of Haskell's native tuples; whereas the primary purpose of 'Only' is to provide the traditionally so named type-wrapper for attaching typeclass instances.