This package provides a canonical anonymous 1-tuple type missing from Haskell for attaching typeclass instances.
NOTE: There is also the 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