StaticArrays.jl

The distinction in Julia isn't between value versus reference types (which have fundamentally incompatible semantics), it's immutable types (declared using `struct`) versus mutable types (declared using `mutable struct`). Immutable types are generally stack allocated and need not even be fully materialized, whereas mutable types are typically heap allocated and fully materialized. The built-in array-type is mutable and can change size. As you say, these can be preallocated and modified in place with a rich collection of in-place, mutating algorithms in the standard library, but sometimes that's not quite enough. If you want fixed-size, stack-allocated arrays, you can use the StaticArrays package [1], which provides precisely such types. Aside from immutability, stack allocation and amazing performance, StaticArrays look and behave just li