A generalization of NonEmptyList to non-List things. For
example, OneAnd[Vector, A] is a non-empty Vector of A.
Only head and tail are provided as direct methods, because
there's little you can do with a OneAnd without knowing a bit
about F. So useful functions are provided in the form of
typeclass instances on OneAnd's companion; in combination with
syntax extensions provided by scalaz.syntax, OneAnd has a
large possible set of methods available by importing. For
example, Applicative on this requires ApplicativePlus[F], and
Traverse1 on this requires Traverse[F]. See the companion
documentation for a complete list of instances.
Additionally, unlike λ[α => (α, F[α])], the behavior of typeclass
operations on OneAnd should be preserved across the natural
transformation to scalaz.NonEmptyList where one exists. That
is it should "be like" a nonempty structure. For example,
ap-ing two OneAnd[Vector, *]s or NonEmptyLists of lengths
a and b yields a sequence of same type of length a×b, but
two λ[α => (α, Vector[α])]s of length c and d ap to one of
length 1+(c–1)×(d–1). For another example, point of the
former two yield a one-element sequence, but point of the latter
yields a two-element sequence.
- Since
7.0.3
- Companion
- object