Cool. Somewhat different but similar... In Julia, types with no fields are automatically singletons and an array size-zero immutable values takes no storage:

Cool. Somewhat different but similar... In Julia, types with no fields are automatically singletons and an array size-zero immutable values takes no storage: julia> sweet_nothings = Array(Nothing,typemax(Int)) 9223372036854775807-element Array{Nothing,1}: nothing nothing ⋮ nothing nothing julia> sizeof(sweet_nothings) 0 This seems like a cute, useless trick but sometimes it's quite useful. For example, the Set{T} is implemented by wrapping a Dict{T,Nothing} and the array of values in the Dict object takes no storage and of course all access is optimized away.