Modules vs Packages

Modules are used to group multiple functions and definitions together. Packages group multiple modules together with various metadata.

Create a custom module

Open up a new .jl file to create your own module. Here I named the file “testModule.jl”. In the file, one can group functions and/or other definitions together. Two functions are grouped by the module myModule. Only myfunction is exported.

module myModule 
export myfunction 

function myfunction()
    println("Hello, friend")
end 

function mysecretfunction()
    println("Hello, secret friend")
end 

end

Load modules

To load modules, use either using or import. using will only make export lists accessible without specifying it with the module name. For example, mysecretfunction() will return an error.

include("testModule.jl")
using .myModule 
mysecretfunction()

However, we can access it with

myModule.mysecretfunction()

julia> Hello, secret friend

Using import,

include("testModule.jl")
import .myModule
myModule.myfunction()

julia> Hello, friend

myModule.mysecretfunction()

julia> Hello, secret friend

myfunction() without a module name will give you an UndefVarError.

Reference

https://en.wikibooks.org/wiki/Introducing_Julia/Modules_and_packages

https://docs.julialang.org/en/v1/manual/modules/