Lazy pattern matching in Scala made even lazier with scalaz's Need.

gistfile1.scala

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scala> import scalaz._
import scalaz._

scala> val (foo, bar, baz) = (Need({println("foo") ; "foo"}), Need({ println("bar") ; "bar"}), Need({ println("baz") ; "baz"}))
foo: scalaz.Need[java.lang.String] = scalaz.Need$$anon$4@1d90d034
bar: scalaz.Need[java.lang.String] = scalaz.Need$$anon$4@e551516
baz: scalaz.Need[java.lang.String] = scalaz.Need$$anon$4@73db5eb3

scala> lazy val List(a, b, c) = List(foo, bar, baz)
a: scalaz.Need[java.lang.String] = <lazy>
b: scalaz.Need[java.lang.String] = <lazy>
c: scalaz.Need[java.lang.String] = <lazy>

scala> a
res0: scalaz.Need[java.lang.String] = scalaz.Need$$anon$4@1d90d034

scala> b
res1: scalaz.Need[java.lang.String] = scalaz.Need$$anon$4@e551516

scala> c
res2: scalaz.Need[java.lang.String] = scalaz.Need$$anon$4@73db5eb3

scala> a.value
foo
res3: java.lang.String = foo

scala> b.value
bar
res4: java.lang.String = bar

scala> c.value
baz
res5: java.lang.String = baz

What does the first level of laziness (lazy vals) gain you that using Need doesn't?