Skip to content

Instantly share code, notes, and snippets.

@milessabin

milessabin/gist:743407c0c46a6eaa17ce

Created February 18, 2015 10:58
Show Gist options
  • Save milessabin/743407c0c46a6eaa17ce to your computer and use it in GitHub Desktop.
Save milessabin/743407c0c46a6eaa17ce to your computer and use it in GitHub Desktop.
Download ZIP
Raw
gistfile1.txt
scala> import ops.nat._
import ops.nat._
scala> def foo[T, N <: Nat](l: Sized[Seq[T], N])(implicit ev: LTEq[N, _3]) = l
foo: [T, N <: shapeless.Nat](l: shapeless.Sized[Seq[T],N])(implicit ev: shapeless.ops.nat.LTEq[N,shapeless.nat._3])shapeless.Sized[Seq[T],N]
scala> val l1 = Sized(1, 2, 3)
l1: shapeless.Sized[scala.collection.immutable.IndexedSeq[Int],shapeless.nat._3] = shapeless.Sized@17191095
scala> val l2 = Sized(1, 2, 3, 4)
l2: shapeless.Sized[scala.collection.immutable.IndexedSeq[Int],shapeless.nat._4] = shapeless.Sized@babb5a21
scala> foo(l1)
res3: shapeless.Sized[Seq[Int],shapeless.nat._3] = shapeless.Sized@17191095
scala> foo(l2)
<console>:21: error: could not find implicit value for parameter ev: shapeless.ops.nat.LTEq[shapeless.nat._4,shapeless.nat._3]
foo(l2)
^
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment