From 9393f4adacbd7ec2d720a51befa6cd44b46f65fd Mon Sep 17 00:00:00 2001
From: David Anthoff <anthoff@berkeley.edu>
Date: Wed, 22 Feb 2017 13:34:02 -0800
Subject: [PATCH] Add IsIterable trait (#25)

Add IsIterable trait
---
 src/base-traits.jl  | 8 +++++++-
 test/base-traits.jl | 5 +++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/base-traits.jl b/src/base-traits.jl
index eb1ac3c..28f90ed 100644
--- a/src/base-traits.jl
+++ b/src/base-traits.jl
@@ -4,7 +4,7 @@ using SimpleTraits
 using Compat
 
 export IsLeafType, IsBits, IsImmutable, IsContiguous, IsIndexLinear,
-       IsAnything, IsNothing, IsCallable
+       IsAnything, IsNothing, IsCallable, IsIterable
 
 "Trait which contains all types"
 @traitdef IsAnything{X}
@@ -57,4 +57,10 @@ end
 
 Base.@deprecate_binding IsFastLinearIndex IsIndexLinear
 
+"Trait of all iterable types"
+@traitdef IsIterable{X}
+@generated function SimpleTraits.trait{X}(::Type{IsIterable{X}})
+    method_exists(start, Tuple{X}) ? :(IsIterable{X}) : :(Not{IsIterable{X}})
+end
+
 end # module
diff --git a/test/base-traits.jl b/test/base-traits.jl
index 3c66a4a..1eae587 100644
--- a/test/base-traits.jl
+++ b/test/base-traits.jl
@@ -30,3 +30,8 @@ if VERSION < v"0.5.0-dev"
     # this give deprecation warning in Julia 0.5
     @test istrait(IsCallable{Base.AddFun})
 end
+
+@test istrait(IsIterable{Array})
+@test !istrait(IsIterable{Cmd})
+@test istrait(IsIterable{Base.UnitRange{Int}})
+@test istrait(IsIterable{Base.UnitRange})