Source code on Github
module Test.Anyable where

open import Class.Prelude
open import Class.Anyable
open import Class.Decidable
open import Class.HasOrder

_ : ∃[ x  List   1  2  3  [] ] x > 0
_ = auto

_ : ∃[ x  just 42 ] x > 0
_ = auto

_ : ∄[ x  nothing ] x > 0
_ = auto