I’m trying to understand the different types, but it isn’t completely clear. As far as I understand, primitive types are those that contain one actual value. So are all concrete types, that aren’t containers, primitive types? Did I simplify it too much? As for composite types, are they exclusively…

almost all types are composite types. (and almost all types defined in Julia are “user” defined in the sense that they are defined in normal julia without any special compiler support). The real difference between primitive and composite types is whether they are built out of a single region of pur…

To add: The tremendous majority of Julia users (and developers) will never ever define a primitive type. There are only a handful of them in the Base language (Base.BitInteger, Base.IEEEFloat, Bool, Char, and probably something related to Ptr are the ones that come to mind) and I’ve never seen one …

The Quadmath case is actually quite interesting (and recent, this was only introduced ~2 months ago in cleanups by oscardssmith · Pull Request #92 · JuliaMath/Quadmath.jl · GitHub ). It turns out that the Julia compiler is smart enough to pass primitive types that are AbstractFloats using floating po…

[image] Queenvictoria: As far as I understand, primitive types are those that contain one actual value. So are all concrete types, that aren’t containers, primitive types? Did I simplify it too much? As for composite types, are they exclusively user defined? Or is there an existing type in Juli…

[image] sgaure: whereas an abstract type is merely an organizational element in the type universe, possibly with subtypes (which can be either concrete or abstract). Or neither (it is not a partition). Consider julia> struct Foo{T} x::T end julia> isabstracttype(Foo) false ju…

[image] Tamas_Papp: Concreteness means that all of these parameters have been specified. To expand on this, a type is concrete if it is neither the bottom type (typ == Union{}), a Union type (typ isa Union), nor a UnionAll type (typ isa UnionAll). That is, only DataType types (typ isa DataTyp…

Understanding Primitive and Composite Types

New to Julia

raman_kumar December 12, 2025, 11:51pm 6

Yes, It is difficult to understand by beginners. Earlier I also have raised issue Julia Type system manual confusions.

Topic		Replies	Views
Julia jargon/terminology definitions - please check! General Usage	2	531	January 31, 2022
Primitive and Composite? Types New to Julia	8	3575	December 30, 2018
What is the difference between abstract, composite, and concrete types. General Usage	7	6258	March 15, 2021
Why are some primitive types defined in Julia, and others in the C code? Internals & Design question , type	1	846	March 12, 2021
Julia Type system manual confusions General Usage documentation , type , education	38	1469	October 6, 2025

Understanding Primitive and Composite Types

Related topics