Merge pull request #19 from JuliaMath/teh/promote

Support eltype promotion

Author: timholy

src/closed.jl

@@ -82,3 +82,5 @@ function convert{R<:AbstractUnitRange,I<:Integer}(::Type{R}, i::ClosedInterval{I
 end
 
 range{I<:Integer}(i::ClosedInterval{I}) = convert(UnitRange{I}, i)
+
+Base.promote_rule{T1,T2}(::Type{ClosedInterval{T1}}, ::Type{ClosedInterval{T2}}) = ClosedInterval{promote_type(T1, T2)}

test/runtests.jl

@@ -83,6 +83,8 @@ using Base.Test
 
         @test width(ClosedInterval(3,7)) ≡ 4
         @test width(ClosedInterval(4.0,8.0)) ≡ 4.0
+
+        @test promote(1..2, 1.0..2.0) === (1.0..2.0, 1.0..2.0)
     end
 end