abstract type IdenticalElementArray{T,N} <: AbstractArray{T,N} end

Base.size(x::IdenticalElementArray) = x.dims
Base.IndexStyle(x::IdenticalElementArray) = IndexLinear()

macro identicalelementarray(TypeName, elem)
    T = typeof(eval(elem))

    esc(quote
        struct $TypeName{T,N} <: IdenticalElementArray{T,N}
            dims::NTuple{N,Int}
        end

        ($TypeName)(dims...) = ($TypeName){$(typeof(elem)),length(dims)}(dims)

        Base.getindex(x::$TypeName, idx...) = $elem
    end)
end

@identicalelementarray Foo "foo"

Foo(1,2,3)