[julia-users] How to get template value of abstract type?

[Sheehan Olver]

Suppose I have

abstract Foo{T}
immutable Foo1{T} <:Foo{T} end
immutable Foo2{T} <:Foo{T} end



How can I write a function that returns T given the type?  E.g.: I want to 
do

Base.eltype(::Type{Foo{T}})=T


But this won't work for eltype(Foo1{T})